Seed sowing at the Botanic Garden

Posted on by andy.winfield

By Helen Roberts

Last month I met up with Penny Harms, Glasshouse Co-ordinator at the University of Bristol Botanic Garden to explore the many different plants they grow from seed. At the end of May the garden staff were nearing the end of a mammoth seed sowing frenzy in preparation for the summer ahead, but Penny explained that seed is continuously sown throughout the year depending on a particular plant’s germination requirements. 
We entered the glasshouses via the potting house, which contains a whole range of pots, growing media and tools for propagation. There are different shaped tampers for firming down compost, and numerous dibbers and widgers to gently prick out seedlings. The growing substrate typically used for most seed germinated at the Botanic Garden is a neutral peat-free compost composed mainly of composted bark, coir and composted green material. 
Penny explained the finer details of the growing media used, “This compost can be altered by sieving out larger chunks for those seeds that require a finer grade tilth, such as poppy species. Fine and medium grades can be produced depending on the particular size of the sieve pores with perlite often added to help with drainage and aeration.”

Some seeds need constant warmer temperatures

Seed sowing occurs in a number of places within the gardens. Some seed needs a dose of warmth to get germination underway and are sown in propagators in the glasshouses to ensure a stable warm temperature of about 22°C. Others can be directly sown into prepared soil and include many of the ballast seed garden species like Calendula officinalis and Amaranthus caudatus, which form a display in the gardens. Those species destined for the grain barge are grown under glass and have recently been ferried across to the barge and planted. I spied seedlings destined to make the watery journey including Avena sativa (oats) and Eruca sativa (rocket). 
Some of the Amaranthus caudatus Helen has grown from seed
at home. Photo credit: Helen Roberts.
Back in the warmth of the propagation glasshouses, Penny pointed to a number of seedlings planted at the start of April including the beautiful but very poisonous half-hardy annual Ricinus communis var. gibsonii, otherwise known as the castor oil plant. This species is grown for its dark red metallic foliage and is planted out in the hot border once all risk of frost is past. A dark purple bronze variety of this species, equally as lovely, is ‘New Zealand Purple’. 
Penny explained how to grow Ricinus communis, “The species is easy to germinate from seed, but does require a temperature of 20-25°C, so it is best grown in a propagator case in a cool greenhouse where the temperature can be kept stable. Once big enough, it is carefully pricked out and hardened off to then be planted out in June.”
Growing steadily under cover of glass are a number of seedlings destined for the hot border that act as effective border fillers. They include the lovely canary creeper, Tropaeolum peregrinum, a half-hardy annual climber with pale green stems, leaves and yellow flowers, and Tropaeolum majus ‘Black Velvet’, another half-hardy annual with beautiful almost black flowers. Other climbers sown in the glasshouses are the common but wonderfully scented varieties of Lathyrus odoratus (sweet peas). The sunny yellow flowers of Tithonia rotundifolia ‘Yellow Torch’ and Helianthus ‘Mongolian Giant’ currently growing in the glasshouses are also useful border fillers. The latter species is a giant that grows up to four metres high, making it a favourite amongst children. More delicate looking blooms also need the warmth of the glasshouses for germination, such as Digitalis lanata (Woolley Foxglove), which has woolly spikes of fawn coloured flowers with a pearlized lower lip. 

Some seed is worth the wait

Some seed germinates very quickly if conditions are right – sometimes within a week – but other seed can be extremely difficult and requires a great deal of molly-coddling in order to get germination success. Penny carefully pointed to a seedling of Cardiocrinum giganteum var. yunnanense, the Giant Yunnan Lily, which as an adult is a beast of a plant and can grow up to 2.5 metres with huge fragrant nodding creamy inflorescences. This species is normally propagated from either seed or by bulbs and can take as long as 4 to 5 years before it flowers. It is a monocarpic species that will die after it flowers leaving offsets, which will then become subsequent plants. This is certainly a species for a patient gardener; it takes a long time to flower but it also takes a considerable time to germinate as Penny emphasised.
Blooms of the Cardiocrinum giganteum var yunnanense
– the Giant Yunnan Lily.
Photo credit: Col Ford and Natasha de Vere
[via Flicr CC licence 2.0]
“This species can be tricky to germinate,” explained Penny, “This one has taken over a year to germinate so it is quite special.”
This is a species that appeals partly due to the fantastic inflorescences, but it has freaky (and rather scary) looking seedpods that resemble vegetative heads with fangs. In my opinion, the lengthy germination and time to flowering is worth the wait. 
Tropical and subtropical plants that only survive as mature specimens in the glasshouses can be even trickier to propagate by seed. The seed from Passiflora, a large genus of mostly vines needs to be sown quickly when fresh as dried seed takes much longer to germinate. The subtropical vines of the Aristolochia species, aptly named Dutchman’s pipe, require similar treatment. Species grown at the gardens are A. labiata and A. trilobata, and have beautiful ornate blooms of about 15cm. A. labiata flowers resemble the mottling and coloration of a rooster’s comb. Although tropical and sub tropical species can be a bit trickier to grow up from seed, most species can be sown throughout the year. 
Some species do not need the cosseting of warmth and will happily germinate outside although some seedlings, like borecole (kale), are protected with wire mesh to prevent bird damage particularly from pigeons. Species that have germinated and are growing happily outside at the Garden include the mixed colours of Salvia viridus, more commonly known as the Clary Sage. This produces small spires of lovely flowering bracts loved by pollinators. These are intended for the Mediterranean beds along with the tall spires of Echium italicum, the Pale Bugloss, a beautiful pyramidal plant belonging to the Borage family and Viola arborescens, a pretty violet with large lavender coloured flowers. 
Other plants need to be sown at different times of the year and some species have enough flexibility in this that you can sow depending on when you want a plant to flower in the subsequent year. For most gardeners, autumn and spring sowing are the busy sowing months. At the Botanic Garden, for example the open faced flowers of Papaver somniferum, (Opium Poppy), are sown in the autumn.
“These poppies are treated differently to other poppy species,” said Penny, “in that they have been sown in September and will be good strong plants by the time they are planted out the following year, producing flowers earlier than if seed had been sown in the spring.”

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

Plants and war

Posted on by andy.winfield

By Helen Roberts

For centuries plants have been closely entangled in the complexities of wars and hostilities. Shortages of food during periods of conflict are one of the most pronounced impacts on humans. Conflict can impede our ability to grow and harvest crops as well as distribute food. Restricting the movement of food is a tactic that is used to control territories and ultimately bring down enemies. 
In the 1990s, in sub-Saharan Africa, many countries suffered famine as a result of conflict and this was primarily due to the different sides using food and hunger as political tools. As well as immediate famine in those areas of active war, there were indirect impacts as people were displaced by war and could not return home to plant their crops. Even more recent examples include the siege warfare occurring in many parts of Syria where the act of starvation is used to make opposing sides submit. The devastation and suffering as a result of food shortages to humans is untold during conflict, but the ultimate survival of certain plants can be threatened too.  

Saving seeds in Svalbard

Svalbard Global Seed Vault, Norway.
Photo credit: Amber Case [via Flickr CC licence]

Seed banks – facilities that specialise in collecting and storing seeds that society has deemed worthy of cultivation – are critical in preserving and potentially restoring the plants lost as a result of war. In 2015, researchers made the first ever withdrawal of 38,000 seed samples from such a bank in order to rebuild a seed collection to replace one lost to the conflict in Syria. 

In 2012, when war reached Aleppo, Syria, researchers from the International Center for Agriculture Research in the Dry Areas (ICARDA) shipped seeds representing 87% of their collection to the Svalbard Global Seed Vault in Norway (a subsequent blog will follow on this unique seed bank facility). The remaining seed was shipped out to other international seed banks. The ICARDA facility in Aleppo hosted seed from 150,000 specimens of significant agricultural importance from the Fertile Crescent – the birthplace of agriculture. Many of the plant varieties do not exist in the wild any more, including unique landraces and wild relatives of cereals, legumes and forages and are only represented in seed banks. 
Having fled Aleppo, ICARDA researchers, now in Terbol, Lebanon, have withdrawn some of this seed from Svalbard in order to recreate the collection lost in the war torn city of Aleppo. Seed was also sent to another ICARDA facility in Morocco. The seeds will be planted and allowed to germinate, grown up and seed collected and sent back to Svalbard to continue the loop of important seed conversation and diversity. At the facilities in Lebanon and Morocco, agricultural research will continue on the seed samples with germplasm being distributed worldwide to plant breeders. 

Russian scientists protect seeds with their lives

It is not the first time that scientists have battled for seed survival. Russian scientists during the Second World War were so desperate in their unerring determination to protect an internationally important seed bank from devastation that lives were lost. The man in charge of the collection was Nikolai Vavilov, a Soviet botanist and geneticist most famous for his work on the evolution of domesticated plants. As a child, he had witnessed first hand the horror of food shortages and this spurred him on to a follow a career in the plant sciences concentrating on plant breeding in order to help combat famine in Russia. He has long been considered the founder of modern seed banks. 
Unfortunately, Stalin who foolishly sought short-term solutions to Russia’s problem of famine, did not support his work. Vavilov fell from favour and whilst on a plant collecting expedition in the Carpathian Mountains was taken and incarcerated, slowly dying in prison of starvation in 1943. Vavilov’s vast seed bank survived the 872-day Siege of Leningrad. Dedicated scientists bent on protecting this valuable collection, barricaded themselves into the seed bank building and guarded it against looting. Sadly, they succumbed to either starvation or disease. This was an ironic tragedy considering they refused to eat any of the seed they were so intent on protecting. 

Plant-based resources in short supply

Not only does conflict cause basic food shortages and threaten plant species survival but it can affect the availability of important plant-based resources. Commodities such as rubber, coal, paper, timber, drugs, cotton and hemp, all derived from plants, have played a key part in conflicts. Of course, control of these critical resources has also propelled countries into war, including tea, spices, salt, grain, flour, bread, sugar and rice. 
One of the many ‘Dig for Victory’ posters
of the Second World War.

War also pushes the agricultural and manufacturing boundaries in the production of food and plant materials. One major commodity during the Second World War of vital importance was rubber. Natural rubber supplies from the plantations of Southeast Asia were severed at the start of the war and American forces were faced with the loss of a hugely important resource even though rubber had been stockpiled in the years preceding the war. With the fall of Singapore and the Dutch East Indies in 1942, rubber exports came to a complete standstill. The Americans invested heavily into developing synthetic rubber, but one of the twentieth century’s greatest ethnobotanists, Professor Richard Evans Schultes, was sent into the remote Amazon basin to hunt for wild rubber. For Schultes, this resulted in 12 years of exploratory research deep within the rainforest. 

People in Britain were growing their own to combat food shortages during the Second World War – spurred by iconic posters emblazoned with the words ‘Dig for Victory’. A staggering 1.4 million people dug up their gardens and lawns to grow vegetables and fruit in Britain. It was similarly successful in the US – by May 1943, 100 acres of land in the Portland area of Oregon was being cultivated by just children!

Plants used to commemorate lives lost

During and after conflict, many plants can hold particular meanings for people. The flowers of certain plants are commonly seen as peaceful elements imbuing a sense of calm and many plants are closely associated with the recognition and commemoration of those who have fallen in wars. The red poppy is one of the most emotive and unforgettable flowers because of war. A symbol of remembrance and hope, and worn by millions of people to remember those who have fallen in battle. The idea of using the poppies stemmed from one of the world’s truly poignant poems, ‘In Flanders Fields’ and is now inextricably entwined with the memory or war. It represents a powerful symbol of our relationship with a plant during and after conflict.

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

Sources:

  1. Seed bank aims to protect world’s agricultural inheritance from Syria war. (2016). The Guardian. <http://www.theguardian.com/world/2016/feb/24/seed-bank-aims-to-protect-worlds-agricultural-inheritance-from-syria-war>
  2. ICARDA’s update on its seed retrival from Svalbard <http://www.icarda.org/update/icarda’s-seed-retrieval-mission-svalbard-seed-vault#sthash.5nrDjLb8.dpbs>
  3. Richard D. Bardgett. (2016). Earth Matters: How Soil Underlies Civilization.  Oxford: Oxford University Press.
  4. Wade Davis. (1996). One River: Science, Adventure and Hallucinogenics in the Amazon Basin. London: Simon & Schuster Ltd. 
  5. Kathy Willis & Carolyn Fry. (2014). Plants: From Roots to Riches. London: John Murray. 

The resilient plants of the western Mediterranean

Posted on by andy.winfield

By Helen Roberts

A recent talk to the Friends by Dr Chris Thorogood on the flora of the western Mediterranean was tonic for those of us longing for warmer weather. For Chris, the western Mediterranean has always had great appeal having spent many summers teaching field courses to undergraduate students at the University of Bristol and the last five years conducting fieldwork for his new book, a field guide to the area.

“The flora of the Western Mediterranean is really special. The plants are able to grow in some fascinating but really harsh places,” explains Chris. “Because of these severe conditions, plants have evolved numerous coping mechanisms in order to survive.”

The region is extremely rich botanically, with over 10,000 different species, all of which are specially adapted to particularly taxing conditions. The area covers a huge geographical expanse incorporating the westerly Portuguese Algarve, to Italy in the east, the islands (Balearic Islands, Corsica and Sardinia) and North Africa from Morocco to Tunisia (see my post last week, which discusses these regions in more detail).

A bounty of habitats: scrubby landscapes

There is a diverse range of floral habitats in the region from the scrubby maquis to forests with wonderful understories of orchids. The bare and arid habitats are home to ‘experts’ in drought tolerance; and at the other end of the watery spectrum are the seasonal lakes where deadly predatory plants reside. Humans have shaped the flora as well through thousands of years of agriculture, which has produced a visually evocative landscape throughout the whole Mediterranean basin.

Cistus ladanifer, the common gum cistus.
Photo credit: Henry Bush [via Flickr, CC]

A habitat that we so often associate with the Mediterranean landscape is maquis, which is specific to the Mediterranean area. It is comprised of spiny sclerophyllous  (a fancy word for hard-leafed) tough vegetation, which is specially adapted to cope with severe drought. There are often small trees and shrubs dotted about, often with beautiful understories of bulbs and short-lived annuals. Many of the species are aromatic. Typical species include prickly juniper (Juniperus oxycedrus) and common gum cistus (Cistus ladanifer), both highly pungent plants that are used by the cosmetic industry for their oils.

“The smells that exude from maquis vegetation are wonderful,” exclaims Chris, “and the scent from these aromatic plants just seems to hang on your clothes long afterwards.”

Garrigue vegetation is similar to that of maquis. It differs slightly in that it is low growing in form, occurs closer to the coasts and grows on shallower soils. Due to its close proximity to the coast it is battered by winter storms and winds. The low stature of the garrigue evergreen scrub means that perennials and bulbs are highly visible. The flowering displays in spring are visually spectacular and include wild tulips, crocuses, thymes, mints, helichrysums and lavenders.

Into the woods

The native forests of the western Mediterranean form prominent landscapes occupying quite different terrain than the shrubland regions. The oak woodlands are dominated by the holm and cork oak, with a spectacular understory that offers a refuge for many animals, including the endangered Iberian lynx.

The pine forests of Pinus halepensis and Pinus pinaster occupy coasts and cliffs. Healthy habitats have a particularly distinctive flora and fauna with rarities such as the semi-parasitic Violet Limadore orchid found in the maritime pine forest of Landes in France.

Ceratonia siliqua, commonly known as the carob tree.
Photo credit: Jesus Cabrera [via Flickr, CC]  

Humans have also shaped the forest landscapes of the region to a certain degree. Traditional farming practices in the Mediterranean have created unique assemblages of plants. Olive, carob, fig and almond groves represent landscapes people often associate with the Mediterranean. No other landscape denotes the true essence of the Mediterranean like a grove of olives. The olive is engrained in the lives and culture of the people of the region. Carob groves are also stunning in their composition with the gnarly dark trunks contrasting brilliantly against the green understory. The carob, Ceratonia siliqua, is a member of the ‘peas’ (Fabaceae), the most speciose family in the Mediterranean.

Rare aquatic habitats

Most of the western Mediterranean habitats are dry and parched, but surprisingly there are some wet ecosystems too. These unusual habitats are rare and include some curious species like the carnivorous bladderworts, found in seasonal lakes, which catch insect prey using sticky hairs and trap doors.

“The aquatic habitats of the western Mediterranean are interesting because they are pretty rare,” explained Chris. “Many are only seasonal but they support a wealth of interesting species from tiny forget-me-nots, tongue orchids and the carnivorous bladderworts.”

Tough but not invincible

While the native species of the western Mediterranean might be seen as tough and indestructible in the harsh landscapes they occupy, they are extremely susceptible to invasive alien species (IAS). Chris explained that the two most invasive plants in the region include certain species of Eucalyptus and Acacia. People assume these species are native, probably because they fit into the landscape visually and they can tolerate harsh climatic conditions. However, both these trees can alter native ecosystems and have a negative impact on biodiversity. Unfortunately, many are still planted as ornamental shrubs despite measures drawn up to prohibit the cultivation of them.

Chris explains the danger of one such exotic: “Acacia cyclops is an invasive species that is likely to become the next big invasive in the western Mediterranean. This species forms a mass of vegetation in barren landscapes due to its ability to cope with extremely dry and saline conditions. Ultimately it outcompetes native species.”

These invasive pests steal native plants’ water and change the biochemistry and microbiology of the soil. The native flora is sensitive because the western Mediterranean is exceptionally biodiverse in a relatively small area, with high levels of endemism, particularly on some of the islands. As well as the threat from IAS, there is also intense pressures on these fragile native habitats from humans due to urbanisation, afforestation, and coastal and agricultural development. Effective and timely conservation measures are vital to ensure the survival of these beautiful and botanically rich habitats before it is too late and they go into decline.

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

The evolution of a predatory plant

Posted on by andy.winfield

By Nicola Temple

We keep a Venus flytrap (Dionaea muscipula) in our bathroom. My son begged me for it, which inevitably means I look after it. Having seen these carnivorous little delights in the glasshouses at the University of Bristol Botanic Garden, I have learned that humidity and moisture are key to its happiness – hence it’s bathroom location and its constant immersion in a tray of water.

The leaves of  the Venus flytrap, open (foreground) and
wrapped around its prey (background, right).
Photo credit: Shelby Temple
While I mostly leave my son to do the part he loves best – feeding – I can’t deny my own fascination with it. The leaves, converted to ambush traps through evolution, have to have enough stimulation by an unsuspecting insect to warrant the plant investing the energy to snap the trap shut.  Once the trap is shut, the plant estimates the size of the prey based on the amount of stimulation of the sensory ‘hairs’ triggered by the trapped (and no doubt panicked) insect. If there is a sufficient signal from the sensory hairs, the plant starts to produce enzymes and proteins that will help it digest and absorb the prey. It’s the stuff of nightmares…for the insect.
So what evolutionary steps transformed a leaf designed to harvest light from the sun into a leaf designed to trap prey? New research published this week in the journal Genome Researchhas provided some insight into the origins of the Venus flytrap’s trap.

It’s a leaf with a hint of root and a dash of…tongue?

Professors Rainer Hendrich and Jörg Schultz led a team of scientists from Julius-Maximilians-Universität Wüuzburg (JMU) in Bavaria, Germany who looked at the genes being expressed by the traps. They found that the traps not only had active genes typical of leaves, but also those typically found in roots.
A close up view of the trap, which shows the sensory ‘hairs’.
Photo credit: Shelby Temple
There are dome-shaped glands on the surface of the trap. The outer layer of each gland secretes the digestive enzymes, but the middle layer has foldings that increase the surface area – reminiscent of microvilli in the human intestine. It is thought that this is where nutrient absorption takes place. As this is a major function of roots, it is not surprising that some of the same genes are required.
Now…about about that tongue. I mentioned above that the plant releases digestive enzymes if it receives enough stimulation within the closed trap. But what if the insect dies very quickly after being trapped? The plant has a receptor in the trap that can detect chitin – the main constituent of an insect’s exoskeleton.  So even if the insect is no longer moving, the plant can ‘taste’ the insect in the trap and begin digesting.


Switching from defence to offence

When non-carnivorous plants come into contact with chitin, it is usually not going to turn out well for the plant –  they are under attack by herbivorous insects. Henrich and Schultz looked at the defence mechanism triggered by insects feeding on the non-carnivorous plant thale cress (Arabidopsis thaliana). They found that the plant in defence mode activates the same genes in the same pattern as the Venus flytrap in attack mode.
“In the Venus flytrap these defensive processes have been reprogrammed during evolution. The plant now uses them to eat insects,” explains Hedrich.
In both cases, mechanical stimulation (whether a chewing insect or a trapped one) generates an electrical impulse that activates the release of the hormone jasmonate. In Arabidopsisthis hormone begins a cascade of events that starts the production of various chemicals that deter the insect or make the leaves hard to digest. In the Venus flytrap, however, jasmonate starts the digestion of the insect and uptake of the nutrients.
So, the ancestor of the Venus flytrap had all the machinery in place for detecting insects and triggering a chemical response to their presence, but evolution managed to shift it from a defensive strategy to a very effective offence.

Source: 

“Venus flytrap carnivorous life style builds on herbivore defense strategies”, Felix Bemm, Dirk Becker, Christina Larisch, Ines Kreuzer, Maria Escalante-Perez, Waltraud X. Schulze, Markus Ankenbrand, Anna-Lena Keller Van der Weyer, Elzbieta Krol, Khaled A. Al-Rasheid, Axel Mithöfer, Andreas P. Weber, Jörg Schultz, Rainer Hedrich. Genome Research, DOI: 10.1101/gr.202200.115

Floral visits to the western Mediterranean

Posted on by andy.winfield

By Helen Roberts

A floral excursion to the western Mediterranean at this time of year appeals to many of us. The anticipation of warm weather, beautiful landscapes and a dizzyingly diverse range of exquisite wild flowers and I want to pack my bags in a flash. I certainly felt that way when I saw some of the images of the region’s wild flowers in a recent Friends‘ talk given by botanist Dr Chris Thorogood.
However, if you cannot escape overseas, then the Mediterranean collection at the University of Bristol Botanic Garden will give you a taste of some of the Mediterranean Basin species although you will have to wait till later in the year to see some of the flowers in bloom. 
If you do have a trip in mind though, here are a few of Chris Thorogood’s favourite spots to see the wild flowers of the western Mediterranean:
Cape St Vincent, Portugal. Photo courtesy of Peter Broster via
Flickr [CC license]

The Algarve, Portugal:

This area has a diverse flora due to varied geology and weather with numerous endemic species and beautiful wild flower meadows. Cape St Vincent, the most south-westerly point in the area and a vast nature reserve, has a spectacular display of flowers in the spring and early summer (January through to the end of May). There are many unique species of thyme and endemic rarities like the tiny diamond flower (Ionopsidium acaule).

Almeria, Spain:

This province is located in the southeast of the Iberian Peninsula and has a wealth of species adapted to cope with extremely dry conditions. Many plants are salt tolerant including sea lavenders like Limoniuminsigne and the rare low growing lily, Androcymbium europaeum whose flowers emerge on sand dunes in mid winter. An area called Cabo de Gata, an impressive tract of volcanic cliffs, is host to numerous unusual species. Many of these are freakishly odd looking from the succulent Caralluma europaea with its purple and yellow striped flowers to the phallic form of the parasitic Cynomorium coccineum.

Cap de Formentor, Mallorca:

This peninsula in the northeast of the island has many unique sea lavenders and orchids. Endemics are closely dotted only metres apart. Much of the landscape is fairly inaccessible due to its rocky and precipitous nature so one needs to be fairly adventurous to spot some species. Notable endemic species include Arum pictum, an arum that smells of rotten meat to attract its fly pollinators and a species of St John’s Wort unique to Mallorca, Hypericum balearicum.

Maremma, Southern Tuscany, Italy:

The Maremma region is rich in wild flowers and contains 25% of all Italian flora. It has a unique geology and extremely varied landscapes including the protected coast, swathes of pine forest and abandoned agricultural plains. The giant fennel, Ferula communis, is one such distinctive plant with its towering inflorescences that can take many years to develop.

Gargano National Park, Puglia, Italy:

The yellow bee orchid (Ophrys lutea) is one of the orchid
species found in Gargano National Park.
Photo credit: Alastair Rae [via Flickr, CC license]
This park has a unique flora and are highly specialised for growing in certain conditions many being endemic. The park covers a vast area and as a result the landscapes are varied from rich beech forests, steep cliffs, karstic plateaus and scrubby maquis. There are many orchid species here (over 65) including some unique bee orchids.

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

Plants that work together

Posted on by andy.winfield

By Helen Roberts

As we roll into spring, gardeners eagerly collect packets of flower and vegetable seed to plant in their gardens. I have my disorganised pile of seeds ready and waiting, nestled in their respective packets, overflowing out of a tin stored on my kitchen dresser. Random seed that I have gleaned from gardens over the course of the year can be found in bags and random pockets.

Companion planting.
Photo credit: Brian Pettinger courtesy of Flickr.

My vegetable garden at home is minuscule and consists of a number of pots in the front and rear garden. I don’t own a greenhouse but use an area in my parent’s and beg ground from a friend to grow larger vegetables. Space is limited and therefore my crop is valuable. I don’t want attacks by cabbage white or carrot fly, I need to grow at different levels to maximise space and grow a wide range of small crops to give a varied meal. This has made me think more about what I can do to increase my crop productivity. I never use pesticides or herbicides in my garden and my resolve in this has been reinforced by recent press coverage over the importance of urban gardens for pollinators. I actually quite like cabbage white butterflies – my children do anyway – and they would be horrified if they knew I sprayed to rid the garden of them. Instead, I have decided to use the art of companion planting.

What is companion planting?

Companion planting is an age-old agricultural technique used for centuries across the world. It involves the idea of planting crops that are mutually beneficial to each other in order to increase productivity.

Why should gardeners companion plant?

Companion planting has a very wide number of benefits and uses:

1. Mix it up

It is best not to put all of your eggs in one basket when growing crops – grow a mix of crops rather than a monoculture so if one crop fails you have other crops as a fall back option. Moreover, a mix of crops will make it more difficult for pests to find their host plants, a hypothesis known as the ‘disruptive-crop hypothesis’.

2. Plants that give a helping hand

The other advantage is, if like me your garden is space constrained, you can plant on different levels. For example, a tall crop (such as corn) can provide a trellis support for a climbing crop (such as beans) and a ground crop (such as squash) provides shade and discourages weeds. You get three crops in a small amount of space and the companion plants provide physical advantages for the other crops.

3. Provide a home

Some plants provide shelter and shade for other plants; for example, the planting of corn can provide shade for lettuce or spinach (although most vegetable planting in this country requires as much sun as possible). Companion plants can also provide refuges for many beneficial insects.

4. Pest control

Marigolds are supposed to help keep aphids away from tomato
plants. Photo credit: Ruth Hartnup (on Flickr).

Companion planting is also supposedly helpful in pest suppression through the release of repellent chemicals. Numerous companion plants also attract beneficial insects, such as ladybirds and lacewings, which predate on crop pests and many of these insects also act as important pollinators. Some plant species are used as ‘trap-crops’ drawing the attention of pests away from the crop and acting as sacrificial plants. Companion plants also provide a visual distraction to pests. In a monoculture, pests move easily from one plant to another, but companion plants break up this assault.

Folklore or scientific fact?

It is hard to know whether some traditional planting combinations that have endured the decades are based on any sound evidence of benefits. Certainly there is plenty of information about companion planting in the popular press and gardening books, but most is not backed up by any rigorous scientific trials in the peer reviewed literature. In academic literature, experimental results investigating the use of certain companion plants are varied as to their effectiveness. Here are some examples that I have come across:

Odorous onions

I learned from my maternal grandfather to plant Allium species in amongst my carrot rows to help deter the pesky carrot fly, Psila rosae. This annoying pest feeds not only on the roots of carrots but also on other crops too including parsnip, celery, parsley and celeriac. The small 9 mm creamy white maggots cause scarring of the tap roots making them inedible and more prone to secondary rots. This year I plan to plant my carrots in amongst garlic chives, a plant similar to the onion chive and which also produces pretty white edible flowers.

It is generally thought that aromatic species deter pests by exuding repellent chemicals. Most relevant to the carrot-allium combination was a study that looked at mixed cropping of onion and carrots and the effects on pests of these crops. They found that there were reduced attacks by carrot fly compared to monocultures of both crops and that when the plants were planted together in high densities this also reduced plant pests and increased predators of carrot fly eggs. Stan Finch and his colleagues from Horticulture Research International in Warwick found no evidence that odours from aromatic plants repel or deter crop pests, suggesting that reduced attacks on host plants were a result of other mechanisms, such as simple disruptive effect.

Get a sniff of marigolds

I am not a big fan of Tagetes species, more commonly known as marigolds. They just remind me of old fashioned bedding plants in staid Victorian parks, but if they ward off pests in the vegetable plot then I am willing to use them. Tagetes sp. exude a strong odour that is apparently not pleasant for plant pests. They are supposedly useful to plant with tomatoes to ward off greenfly but I have yet to find any scientific literature to support this planting combination. Again, Finch and his associates specifically found that it was not the odour of the marigolds that repelled the pests, but simply the fact that they acted as a diversion for the pests.

Setting a trap

I often grow pots of nasturtium (Tropaeolum majus) in my garden. I like the look of the flowers and especially the leaves, using them as salad garnishes and the seed to make capers. This plant is said to help attract black fly, aphids and other pests away from host plants acting as a crop trap and functioning as a sacrificial plant. There are mixed results as to whether nasturtiums really do this. One year in my garden I grew cabbage and nasturtium together and both crops were smothered in cabbage white caterpillars. The butterflies definitely did not show a preference for the Nasturtium and the caterpillars eventually obliterated both plants. Certainly there is not a wide range of recent academic literature investigating the use of nasturtiums as a companion plant. However, according to the Royal Horticultural Society (RHS), this plant is beneficial to pollinators and as I can also eat it, I plan to trial a variety known as Blue Pepe, known for its distinctive bluish leaves and bright red flowers.

The scientific literature on many companion plant combinations is mixed, but what is clear is that there are no disadvantages to using companion planting. The physical advantages of companion planting will be evident even if the other benefits are less obvious, and many companion plants can be found in the RHS’s ‘Perfect for Pollinators plant list‘. Even if you don’t get increased crop productivity, then the garden will be diverse and look beautiful too.

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

Sources:

Associate Professor Jane Mt. Pleasant 

Uvah, I. I. I. and Coaker, T. H.  Effect of mixed cropping on some insect pests of carrots and onions. Entomologia Experimentalis et Applicata 1984; 36: 159-167

Finch, S., Billiald, H. and Collier, R. H. Companion planting-do aromatic plants disrupt host-plant finding by the cabbage root fly and the onion fly more effectively than non-aromatic plants? Entomologia Experimentalis et Applicata 2003; 109: 183-195

Keeping your head above water: plants coping with waterlogging

Posted on by andy.winfield

By Helen Roberts

Flooding on the Somerset Levels.
Photo credit: Nigel Mykura [CC BY-SA 2.0],
via Wikimedia Commons

Britain has had its fair share of flooding over the last couple of years. In 2014, the Somerset Levels was under water for weeks and 2015 saw some truly devastating flooding occurring in the northwest of England. Flooding can have detrimental effects on our own lives, but also on plant communities.

Waterlogging of plants can cause chlorosis (loss of the normal green colour) of the leaves, root rot and eventually death. It’s a common problem that many gardeners face every day and there are different techniques to cope with this ever persistent problem on our shores. Precautions are even taken at the University of Bristol Botanic Garden during this wet weather.

“As far as the garden borders go, we’re very careful about never walking on them when there’s been heavy rain,” explained Andy Winfield, horticultural technician at the Botanic Garden. “If we have to get on a border for any reason, we use a board and then fork over where it was to prevent compaction and a pan forming. When a pan forms, then water is more likely to sit on the surface and create problems.”

How does waterlogging affect soils and plants?

The profile of a soil will greatly affect its interaction with water. Soils are composed of solid material with spaces filled with water, gases, roots and other living organisms – these attributes impact water retention and drainage. For example, clay soils have small pore spaces and so retain more water compared with sandy loams.

Subsoils can also influence soil structure and its interaction with water. Waterlogged soils are not only affected by the amount of water coming into the system, but by the soil’s ability to disperse and absorb that water.

When soils are waterlogged, the air spaces between the particles are filled with water and the movement of gases within the soils is inhibited preventing the roots from respiring properly. Gases such as ethylene and carbon dioxide begin to accumulate, which leads to further negative impacts on root growth. Anaerobic processes begin to changes the soil biochemistry, which leads to plant death through the build up of toxins within soils.

What is happening to plants at a cellular level when faced with anoxic or hypoxic conditions? 

When plants are waterlogged, they are not getting enough oxygen via the roots for cellular respiration and energy production. Because the plants cannot obtain oxygen via the roots, plants turn on their own energy reserves. This is much like when we use our muscles during strenuous exercise and we can’t get sufficient oxygen to the hard working cells – the cells undergo anaerobic respiration, which produces lactic acid. Plants can also undergo anaerobic respiration, but it is not sustainable and eventually, the plant dies as the demand for energy exceeds the supply.

Until recently little was known about how some plants cope with the stress of waterlogging. However, researchers from the Max Planck Institute of Molecular Plant Physiology, with colleagues from Italy and the Netherlands, have discovered a protein that triggers the activation of stress response genes when oxygen levels drop due to waterlogging. This protein is attached to the cell membrane under normal aerobic conditions, but when levels drop it detaches from the membrane and relocates to the nucleus where it switches on the stress genes. When oxygen levels return to normal, the protein degrades and the stress response genes switch off again.

How some plants have evolved to cope with anoxic and hypoxic conditions

When out walking as a child on Exmoor, I would often pick the stems of the soft rush, Juncus effusus, and peel back the green outer coating to reveal the soft, husky white pith inside. I was amazed when an adult told me this material was once used for making rush lights. The pith would be extracted from the rush leaves and combined with fat or grease to provide a source of artificial light. This pithy material is interesting though in this context as it contains a tissue called aerenchyma, which is usually found in the roots and stems of many hydrophytes (plants adapted for living in water). The tissue has large interconnected intercellular gas spaces that help to oxygenate the roots and increase buoyancy.

Other plants adapted to soggy conditions will produce fine surface roots called adventitious roots. These roots scavenge oxygen from the surface where there is a thin aerobic layer. Many of the Melaleuca species, mostly from Australia, use this way of coping with water hypoxia.

Some plants are adapted to rise above it all; they elongate their shoots to get above the water, as is the case with some floodplain Rumex species (docks and sorrels). Nymphaea species (the water lilies) – which you can see in the Botanic Garden glasshouses –  have a hugely elongated petiole, often more that two metres long, to keep their leaves and flowers at the water surface.

Arial roots (pneumatophores) of the grey mangrove
(Avicennia marina var resinifera) from South Australia.
Photo Credit: Peripitus (Own work) [GFDL, CC-BY-SA-3.0 )
or CC BY-SA 2.5-2.0-1.0 ], via Wikimedia Commons

Large tree species have also adapted their roots to cope with swamp-like conditions. These strange looking roots are known as pneumatophores – woody extensions that grow vertically upwards from the underground root system to reach above water and capture that much needed oxygen. The bald cypress, Taxodium distichum, which is found in the southern USA in lowland river floodplains and swamps, forms these roots that look like knees sticking up out of the water. The actual surface of the root is pockmarked with many lenticels, which are small stomata-like pores found in the bark that allow gaseous exchange. Other swamp and mangrove species have variations of these root adaptations to cope with low oxygen levels including pencil and cone roots (which belong to the pneumatophore group) and other types of aerial roots like knee, stilt, peg and plank roots. These roots differ in both their morphology and function, but are ultimately adapted to cope with waterlogging and often saline conditions.

The importance of wetlands as carbon sinks

Waterlogged lands are not all doom and gloom, in fact, bogginess is vitally important in terms of the Earth’s climate. Peatlands fall into that category. They act as important carbon sinks and currently cover about four per cent of the Earth’s land surface. Drainage of these areas of peatlands and wetlands for agricultural use leads to increases in greenhouse gas emissions. Researchers are actively trying to understand the effects of climate change on peatlands globally and there have been pushes to effectively  conserve and manage these precious ecosystems.

Sources:

Guillermina M. Mendiondo, Daniel J. Gibbs, Miriam Szurman-Zubrzycka, Arnd Korn, Julietta Marquez, Iwona Szarejko, Miroslaw Maluszynski, John King, Barry Axcell, Katherine Smart, Francoise Corbineau, Michael J. Holdsworth. Enhanced waterlogging tolerance in barley by manipulation of expression of the N-end rule pathway E3 ligasePROTEOLYSIS6. Plant Biotechnology Journal, 2015; DOI: 10.1111/pbi.12334

Francesco Licausi, Monika Kosmacz, Daan A. Weits, Beatrice Giuntoli, Federico M. Giorgi, Laurentius A. C. J. Voesenek, Pierdomenico Perata, Joost T. van Dongen. Oxygen sensing in plants is mediated by an N-end rule pathway for protein destabilization. Nature, 2011; DOI: 10.1038/nature10536

Daniel J. Gibbs, Seung Cho Lee, Nurulhikma Md Isa, Silvia Gramuglia, Takeshi Fukao, George W. Bassel, Cristina Sousa Correia, Françoise Corbineau, Frederica L. Theodoulou, Julia Bailey-Serres, Michael J. Holdsworth. Homeostatic response to hypoxia is regulated by the N-end rule pathway in plants. Nature, 2011; DOI: 10.1038/nature10534

To grow or not to grow: plant propagation at the Botanic Garden

Posted on by andy.winfield

By Helen Roberts

At the start of December, I met up with Penny Harms, Glasshouse Co-ordinator at the University of Bristol Botanic Garden, to discuss the plants that are propagated at the Garden and how this valuable work is carried out. Over the course of the year, I will be investigating the different forms of propagation techniques used in the Garden to maintain and enhance their existing stock of plants. I will cover briefly how these techniques are carried out (bearing in mind that there are a plethora of books available on plant propagation), but I’ll also examine what is happening at the cellular level and examine the ‘why’ behind certain propagating techniques.

As Penny and I examined some seedling plants, she explained to me why propagation is so important at the Botanic Garden. “If we lose some plants outdoors in a cold wet winter, we have a back up of new plants. Some are not simply insurance plants, but are taken as cuttings as a necessity every year as they survive in our climate as annuals, particularly those plants from the South African collection. Others, such as the Mediterranean plants, do not survive as long here in Bristol as it’s generally much wetter and therefore they need to be replaced fairly frequently. Most plants we take from cuttings are mainly tender perennials and frost tender plants.”

Propagation in the Garden won’t likely restart until the spring depending on weather conditions.

In the glasshouses, Penny showed me many of the plants that have been propagated from cuttings, including some beautiful decorative Aeonium species (commonly known as tree houseleek), as well as Pelargonium (geranium), Clematis, Salvia and Passiflora (passion vines) species. Some plants raised from cuttings  are placed in a unit that is misted with water regularly and the bottom is heated to a temperature of 25°C in order to encourage roots to form. The plants all looked wonderfully healthy, not at all like my puny looking specimens that I had taken cuttings of back in September at home. However, the plants that really caught my eye were some small fern plants potted up, which Penny called “fernlets”.

Ferntastic ferns

Ferns belong to the plant division of pteridophytes (spore-producing vascular plants) and are extremely diverse in habitat, form and reproductive methods. Most ferns grow in moist warm conditions and very few tolerate dry cold places. Although they aren’t flowering plants, the frond shapes and colours can be exquisite. Closer inspection of the undersides of the leaves reveal beautiful patterns of sporangia – the vessels containing the spores.

Fern reproduction 101

Fern lifecycle
Image credit: Carl Axel Magnus Lindman
[CC BY-SA 3.0], via Wikimedia Commons

Like other plants, ferns have alternating haploid (single set of chromosomes) and diploid (two sets of chromosomes – one from each parent) generations; the haploid gametophyte produces the cells for sexual reproduction while the diploid sporophyte produces spores that produce the gametophyte. Unlike flowering plants where the gametophyte is reduced to the pollen and embryo sac, fern gametophytes are free-living. (Although they are admittedly less conspicuous than the sporophyte we generally identify as ferns.)

In brief, the sporophyte produces spores, which are shed and grow into gametophytes (also often called the prothallium). In some species, individual gametophytes will be either male or female, while in others an individual gametophyte will function as both sexes. When the conditions are right, the gametophyte releases mature sperm from the antheridium, which swim to the egg-producing part called the archegonia under the gametophyte’s underside. Fertilisation produces a zygote, which develops into an embryo and eventually outgrows the gametophyte to become the sporophyte.

The plantlet sailboats on the fronds of Woodwardia prolifera.
Photo credit: Andy Winfield.

Like many other plants, ferns can also reproduce asexually through branching of the underground root stem or rhizome. Some species will even produce leaf proliferations known as plantlets or offsets, such as the beautiful Woodwardia prolifera, which comes from Asia and grows in coastal regions. It’s small plantlets (or “sailboats” as Penny calls them) drop off the plant and fall to the ground, securing themselves quickly with their roots.

Fern propagation at the Botanic Garden

Fern spores are carefully collected when the ferns are sporolating by cutting fronds and letting spores fall into paper bags. Spores are only collected when they are ripe; usually the sporangia will swell and will turn brown, black, blue or orange depending on the species.

“As far as when to collect the spores,” said Penny, “it is really a case of watching and waiting. The beautiful orange [sporangia] on the Phlebodium aureum var glaucum go a slightly darker brown when they are ready, which makes it easier to know when to collect. And if you lightly tap the frond over some white paper you can watch to see if the spores are being released.”

The underside of a frond from Phelbodium aureum var. glaucum,
showing the sporangia. Photo: Andy Winfield.

Penny added that she often collects additional spores by simply placing a fern frond onto a tray containing already wetted peat-neutral compost with bark mulch to allow spores to drop onto the substrate. Penny had great success growing new plants from spores harvested from a miniature tree fern species called Blechnum gibbum. This plant was looking in a sorry state before the move to The Holmes at Stoke Bishop and so Penny collected spores just in case it didn’t survive the move. However, research revealed that this fern was behaving like a deciduous plant -it had died back, but wasn’t dead. Thanks to Penny’s careful propagation, the glasshouse now holds a number of specimens from this species – all grown from spores of the original plant.

The tree huggers

Some the glasshouse ferns are also epiphytic and will reproduce effectively from spores. One such example is Stenochlaena tenufolia, a South African fern that will grow up trees. Its climbing rhizome can reach up to 20m in length and 15mm in diameter. As young plants, they start off on the ground, but soon start to ascend trees, trading in their connection with the soil for life in the trees. Often plants don’t produce fertile fronds until the rhizome has climbed sufficiently to expose the apical region of the plant to sufficient light. These ferns are grown both from spores and vegetatively at the Botanic Garden.

The runners

Other species require a different approach. Diplazium proliferum, a fern that is widespread in the tropics and subtropics, produces little rooting plantlets along its fronds that can be developed into new plants. The frond is simply cut and laid onto bark mulch, pegged with wire and then half buried with the substrate.

The chain fern, Woodwardia radicans (from the Macaronesian region but also found on other Mediterranean islands) also produces bulbils but these are usually located at the ends of the fronds as a hard nodule. The roots start to develop in the air but when they touch the ground will root into the substrate and form new plants.

Penny explained, “We got these plants from Tresco where they grow as huge sprawling mounds. The small bulbils eventually form quite large plants, but are still connected to the original. This gives this fern its very relevant name. New plants can simply have the connection cut and be dug up and transplanted elsewhere.”

A brief step-by-step lesson on how to propagate ferns

At the Botanic Garden ferns are being propagated very successfully, but there is no reason why horticulturists at home should not be able to have the same degree of success. Penny offers her expert advice in propagating ferns by spores below:

Ferns can be propagated vegetatively, by division, or similar to sowing seed from flowering plants, by spores, which are found on the underside of the fern fronds. Some fern species are very difficult to propagate from spores, however Adiantum, Pteris and many Blechnum species are reliable.

Here are the main points for the propagation of cool glasshouse ferns from spores:

  1. The spores should be collected when ripe. The sporangia found on the underside of the frond, will (in most cases) change in colour from a light to dark brown to indicate the spores are ripe. To check, lightly tap the frond to see whether the tiny brown spore cases (sori) are released. If so, the fronds can be cut and gently placed into paper bags in order to collect the fine sori ready for sowing (see point 2) or the frond can be cut and placed directly onto the surface of a pre-prepared tray of compost, allowing the spores to fall naturally as the frond dies away. 
  2. Sow the fern spores. Collect the spores from the bottom of the paper bag and sow immediately. Fresh spores will germinate far more successfully than ones that have been kept for some time and dried out. Use clean, shallow, pots and/or trays with drainage holes. Place a fine layer of gravel on the bottom. Add a layer of peat-free, fine grade compost and gently firm down. Stand the pots and/or trays in water to allow the compost to absorb the water. When the compost is wet, lightly and evenly sow the spores over the surface of the compost. The spores are very fine and on no account should they be covered with more compost, as this will prevent them from germinating.
  3. Keep moist. The trays and/or pots should be covered either with a propagator lid or glass and stood in a shallow tray of water. It is important that the compost does not dry out. 
  4. Position in a semi shaded spot ideally at temperature of 16 – 20°C.
  5. Once the spores start to germinate, the young fern plants (prothalli) should become visible within a couple of weeks. Allow the prothalli to establish themselves for a little while before moving on to the next stage, that of pricking out the delicate new plants.

 Moisture is the most important element for the successful propagation of ferns. 

Saving our nation’s lost landscapes

Posted on by andy.winfield

By Helen Roberts

Historic gardens are an integral part of our cultural link with landscapes; a place where we can connect with nature. They represent a form of artistic expression and illustrate snapshots of past ages, cultures and societies. For that reason alone these garden masterpieces deserve recognition and preservation. 
Often the final level of protection for many of these gardens falls to English Heritage, a registered charity, independent of government since April 2015, which essentially acts as guardians for the upkeep of some 400 historic sites. English Heritage is often seen as the last resort of protection for these sites, some of which are so special that the government has stepped in to look after them and rescue them for the nation. 
Late last year the Friends’ Lecture was given by Christopher Wedell, a former trainee of The University of Bristol Botanic Garden (21 years ago) and now senior gardens advisor to English Heritage. 
Bridge in Sheffield Park Garden.
Photo credit: ReflectedSerendipity
courtesy Flickr [CC BY-SA 2.0], via Wikimedia Commons
Christopher’s horticultural career began early; as a teenager he already expressed a keen interest in the outdoors. A stint of work at Sheffield Park in Sussex fuelled his passion for horticulture and historic landscapes and led to a degree in Horticulture at Writtle College with a final year dissertation on historic gardens. After his work at the University of Bristol Botanic Garden and Tylney Hall, Christopher obtained his Kew Diploma in Horticulture and then spent 18 months working in the famous Palm House. From Kew he went to Wisley where he eventually became superintendent under curator. When a 6-month contract offered itself at English Heritage he applied and 7 years later he is looking after 23 historic and contemporary gardens ranging from Elizabethan to contemporary in design.  
Christopher spoke in detail about the gardens under the care of English Heritage, the complexities of restoration and the many challenges the team faces when completing historic garden works. 

The importance of authenticity

The restoration of historic gardens is a difficult task in itself when there is a lack of historical information in the form of maps, descriptions and documents. Often gardens are multi-layered over time, making it difficult to know at what particular point in time to restore the garden to. 
Belsay Hall, a thirteenth century site located just north of Newcastle has magnificent Grade I listed gardens and were primarily the work of Sir Charles Monck (1779-1867). He was influenced by the Picturesque movement, which sought to create landscapes less conventionally beautiful and more naturalistic in design. The restoration of the unique Quarry Garden, a dramatic place with a special microclimate with many exotic trees and shrubs, presented English Heritage with a challenge of maintaining the correct authenticity. To achieve this, the team used a number of photographs collected over the decades to aid in the restoration process.
“Photographic and historical documents are very important in the restoration process,” explained Christopher, “and it is vital that as much historical information is collated as possible, thereby restoring the landscape at the most significant point in historical time”. 
Osborne House from the road to Swiss Cottage.
Photo credit: By Loz Pycock from London, UK
[CC BY-SA 2.0 ], via Wikimedia Commons
Sometimes, as gardens change over time, plants become over-mature and cease to provide the effect for which they were first planted. English Heritage faces a number of challenges with such restoration projects because people often develop strong attachment to these mature trees. One such example includes Sovereign Avenue at Osborne House on the Isle of Wight – the private home of Queen Victoria. The avenue was planted in 1851-1854 with two lines of alternating deciduous and coniferous trees. Over time (as expected), these trees matured, but eventually became too large and made the avenue dark and oppressive. This was not the intention of the design when planted by Prince Albert. English Heritage then faced the challenge of how to visually present this avenue with the possibility of replanting every 50 years to maintain authenticity. 

Maintaining the fabric of the garden

The fabric of a historic garden represents the context in which a garden is situated. Gardens do not simply exist as islands on their own but connect and integrate with surrounding landscapes to create cohesion and robustness, both of which are sought after qualities in designed landscapes. Often it is difficult to maintain connectedness in historic landscapes due to the simple issue of land ownership. 
One such English Heritage example is that of Audley End House, a Jacobean Mansion landscaped by Lancelot ‘Capability’ Brown and set within the rolling countryside of Essex. English Heritage has in their care the mansion and grounds itself, but also a tower located outside of the boundary of the mansion grounds some distance away and the land in between is not under English Heritage ownership. Here, English Heritage faces the difficulty of maintaining a connected landscape, as the sites are geographically distant from one another, but sit within the same landscape. Belsay Hall also faces similar challenges as the existing car park is set within the historical landscape fabric, which disrupts the harmony of the site. 

The visitor experience

It can be difficult to maintain a good visitor experience all year round in many of the English Heritage gardens. Many of the gardens are very seasonal in nature as bedding schemes took precedence over year-round interest. At Kenilworth Castle (just north of Warwick) an Elizabethan garden was created by Robert Dudley, Earl of Leicester in order to seduce Queen Elizabeth I when she was staying at the property for a mere 19 days. This garden was restored in May 2009 using advances in garden archaeology and the survival of a fascinating eyewitness description from 1575. When the garden was originally designed for a short spell of interest, English Heritage now faces the difficult task of creating a garden that is attractive to visitors throughout the year. 
To attract visitors to the gardens, many English Heritage sites hold contemporary art exhibitions, such as the one held at Belsay Hall called ‘Extraordinary Measures’ with many of the installations located in the grounds of the Hall. 
Other attractions to entice families have recently been sensitively incorporated into some historic landscapes. An imaginative wooden play structure for children has proved very popular at Witley Court near Bromsgrove with a tree house in the form of a seed pod, outdoor musical instruments and wobbly bridges, scramble nets and slides. The opening of the beach at Osborne House on the Isle of Wight has been well received with people enjoying swimming, paddling, building sandcastles and looking inside a bathing machine. With the opening of access to the beach though, English Heritage was then faced with the challenge of incorporating essential utilities, such as power and water, into a historic landscape. Other interesting plans for enhancing the visitor experience described by Christopher included the potential restoration of the unique hard tennis court at Down House, home of Charles Darwin, which would provide a great play facility for adults and children alike when visiting this historically significant place. 
“It’s really important that sites do not simply stagnate in terms of a design sense and that the gardens are able to evolve and be used imaginatively,” explained Christopher. 
Many sites have successfully integrated contemporary spaces into the gardens adding a new vitality to these historic places. A new contemporary garden was added in 2000 to the kitchen garden of Osborne House by designer Rupert Golby as part of the contemporary heritage garden project. It includes many plants with names associated with Albert and Victoria. 

The future

Christopher’s message was clear throughout the talk. These gardens need to be brought to life for current and future visitors and be places that continually thrive for decades and centuries hereinafter. 
Christopher emphasised that, “English Heritage is playing a vitally important role in looking after these sites; we are the landscape custodians helping to safeguard some of England’s most treasured historic gardens.”
The next Friends’ Lecture will be given by Nick Wray, Curator, University of Bristol Botanic Garden on 21 January 2016, Frank Theatre, Wills Physics Laboratory from 7:30pm – 9:00pm. Nick will be speaking about the ballast seed garden project. Friends are free with presentation of membership card; non-Friends will be asked for a donation (suggested £5).

The hows, whys and wheres of composting…

Posted on by andy.winfield

By Alida Robey

I have had some intriguing responses to my previous post on composting– most commonly “Hurry up and tell us how to do it!” ; so without further delay, I give you the why, where and (most importantly) how of composting….

Why compost?

There is so much more to composting than simply meeting our own personal needs.  For me, the global urgency is such that I would have us label all shop bought fruit and veg: WARNING: Not composting will lead to the depletion of our soils! Here’s why:

Compost helps regenerate soils and improve soil structure

Current agricultural practices suck nutrient out of the soil. The resultant produce has less nutritious value than in previous generations, [1] meaning we are needing to eat more to get the same nutritional benefits. [2] Commercial fertilisers are designed to promote maximum growth, not necessarily superior nutrient content of the fruit and vegetables produced. Nor do these fertilisers benefit  soil structure and health. The fibre of compost added to soil helps improve water retention and also helps moderate temperature extremes.

It provides a slow release of nutrients (especially nitrogen)

Unlike synthetic fertilisers, compost adds a bank of biological activity to the soil, which encourages beneficial worms and helps to make significant quantities of nutrients (such as nitrogen, phosphorous and potassium) bio-available slowly over time.

Composting keeps organic waste out of the landfill

About a third of household waste is likely to be kitchen-generated organic matter. Composting it yourself reduces increases in your council tax by saving some of the huge costs of domestic waste collection transport and disposal. Also, organic matter in landfill produces methane (a greenhouse gas  that contributes to global warming) and nitrogen-rich leachate (pollutes rivers and streams).

Composting transforms plant material, food waste and other organic matter into humus or compost, which is a richly nutritious soil-like material with the added benefit of microorganisms that help plants take up  the goodness in the soil. In other words, it turns otherwise smelly, unwanted waste into something really productive and pleasant to handle.

Where to compost

A community composting bin in the Shelton Community
Garden in Shelton Stoke-on-Trent, Staffordshire.
Photo credit: Joshua Whiton via Wikimedia Commons

The traditional means of composting is a bin, a heap or an enclosure in a sunny spot in the corner of a garden.  However, you can do some very effective composting even without a garden of your own:
Community composting bins require one or two people to maintain but can receive compostable materials from a community. The compost can then be used for community gardens or by individuals in the community . They can be located in parks, communal gardens, unused corners, on the edge of school grounds and other public/semi-public spaces. 
Wormeries are a wonderful alternative for those in apartments or with limited external space.  A wormery is usually a small stack of trays, which is home to a colony of compost – eating worms (NOT earthworms) that will convert most kitchen waste into wonderfully nutritious ‘worm wee’ and worm castings that can be used to feed indoor or outdoor plants or given away to friends and neighbours to use on theirs.

How to compost

This is what I consider to be the basics.  Once you have tried some of this and found it’s not going as badly as you had imagined, then I suggest you access some of the online information that will help improve your productivity. 

What goes in?

IN: 
Veg peelings & fruit
Coffee grounds, tea bags, egg shells – crushed by a crunch of your hand
Cardboard (torn up no larger than a standard envelope), tissues, loo roll tubes & waste paper – shredded or scrunched up.
Especially welcome are egg boxes (ripped up a bit) and the contents of  paper shredders
Grass-cuttings (so long as you haven’t used weed-killer) and discarded pot plant contents including old compost and dead flowers
Plant prunings – chopped up to help decomposition
Weeds –  so long as they are not in seed, otherwise you will have them sprouting merrily back in the soil.
OUT (of compost bins but IN for wormeries)
Pasta, rice, couscous
Beans, pulses, lentils, cereals
Bread, chapatis, biscuits etc
Plate scrapings
Cheese and dairy products
Meat, fish and bones
Cooked potatoes
The reason many of the items above are excluded from compost bins but not wormeries is their attraction for vermin.
OUT (of everything)
Nappies
Cat and dog poo from animals that have been wormed.

Location, location, location

A typical compost available from
local councils.

For general composting, find a warm sheltered corner preferably reasonably accessible so you are not put off taking stuff there.  Set up your means of containing your compost, a compost bin or bins is the easiest, but a boxed-in area or even just a pile will do.  Your local council may, like Bristol, sell plastic compost bins and deliver them, all for as little as £12-15. You need to bear in mind that you will need to be able to turn the contents occasionally and that worms need access from below.

The great compost bake-off

Underlying the composting process is the chemical transformation of carbon materials (shredded paper, straw, vacuum cleaner dust, leaves, egg boxes, egg shells) and nitrogen materials (grass clippings of untreated grass, weeds, kitchen scraps, coffee grounds) into a whole new product – compost.  It is a bit like baking a cake where the ingredients are deliciously transformed by mixing and baking.  We can control the conditions in our compost to encourage the materials to decompose faster and effectively (i.e. to produce a really good cake rather than a baked lump of goo).
The other factors your composting recipe needs to include are a mix of particle sizes that assist aeration and hold enough (but not too much) moisture.  As with the cake, the mixing and aerating are important success factors between it just working and it being great. If it’s getting smelly, add more carbon materials and aerate it more frequently by turning it over.
Depending on your method, the transformation process can take just a few months.


Layer dress

Start layering your contents, bearing in mind the need to mix carbon and nitrogen items (roughly 2 carbon:1 nitrogen, but adjust according to whether it seems to look and smell healthy).  And just keep adding, remembering that it will all break down a lot smaller. I prefer to have 2 or 3 bins, and empty them out completely from time to time, retrieving the made compost from the bottom and piling the rest back into one bin. This can be a lot easier than turning the contents of individual bins. You can keep one bin of nearly decomposed compost at the ready for when you want to use it in the garden.
Happy composting!

Further resources about composting:

References:

[1] World Economic Forum (14 Dec 2012) What if the World’s Soil Runs Out? Time