Category: gardening

Tea, thatch and early spring

Posted on by andy.winfield

Today as I write this the sun is shining, the birds are in full voice singing, cawing and screeching around the Garden. Bulbs are popping up, crocus are the first with daffodils a week away from carpeting the ground with yellow. Primroses are dotting grassy areas and bees are beginning to forage in the middle of the day; the minimum temperature that a bee can fly is said to be 13 degrees, so when you see one out and about you know the season is changing. In February in this part of the UK we get an extra two and a half minutes of light every day; after February and through March to June it is only two minutes. This is why a lot seems to change in February in the Garden, it is a conduit for spring; the end of January is incomparable to the beginning of March in terms of light, flower and the beginnings of warmth. We’ll still get ice, cold, wet and maybe even snow again between now and summer, but days like this make us feel that winter is nearly behind us.

Crocus appearing in the Garden.

In the Garden there are exciting changes happening. Our South African display has had the framework of a traditional African roundhouse present for much of last year; as I write this it is being thatched with a South African reed called Cape thatching reed; Thamnochortus insignis, the building will then be rendered in a red cob. These features are important for bringing context to the plants around it, being a talking point and attracting people to the Garden where they can leave with maybe a lot, maybe a little, but some new knowledge of the plant world that they didn’t have before.

Lu Yu.

Another development is our Chinese tea plantation. Yes, a tea plantation here in Bristol, just a small one but a tea plantation none the less. When landscaping the area where we’ll grow tea, visitors ask what I’m doing and seem intrigued and interested with the response. Tea is something that is in the heart of UK people, many conversations, moments of relaxation, tears and laughter have happened over a cup of tea and many millions of hands have been warmed on a mug during winter. In China tea drinking dates back 5000 years. Legend has it that Emporer Shen Nung was boiling water when leaves from a wild tree blew into his pot; he was so interested in the aroma that he drank some. He named the brew ch’a, meaning to check or investigate. Tea became integral to the culture of China when Lu Yu, a Chinese scholar, dedicated his life to the study of tea; he wrote a treatise called ‘ The Classic of Tea’ in 760CE, the earliest work dedicated to tea. Today every Chinese household will have tea brewing sets and use tea brewing as a form of welcome, celebration, in family gatherings or to apologise. We’re looking forward to planting our fifteen (so far) Camelia sinensis plants; they should be in the ground by March, which, coincidentally, is when our refreshments open again after the winter…

We look forward to seeing you in the Garden, keep your eyes on the ground and enjoy early spring!

Plant blindness

Posted on by andy.winfield

You may or may not of heard of the term ‘plant blindness’; it’s a phrase that we in the Botanic Garden have been hearing much more of in recent years and will continue to throw around in the future. It refers to the slow shutting off of plant knowledge from generation to generation resulting in an inability to acknowledge plants around us. The simple things that were once common knowledge, such as dock leaves used for nettle stings are becoming bred out of a collective instinct and plants are becoming irrelevant and annoying green things to many people.
I can remember when my eyes were truly opened. I noticed trees that I hadn’t before; as I walked along the street I started looking at the borders and the hanging foliage all around me. Before, I’m not sure what I looked out for in the streets, the pavement or the shops, who knows, but plants for sure changed my life and I see them changing the lives around me at the Botanic Garden. I think I could live to be three hundred and still find something in the plant world that fascinated me. This week I learnt about the incredible relationships between some species of orchid and ants. The ants don’t pollinate the orchid flower but hang around the plant living off an ‘extrafloral’ nectar secreted elsewhere; they then do everything to protect their food source and keep the plant safe. Plants and animals have these delicate relationships that allow both to flourish, and it’s fair to say that ours has become less delicate over the years.
Dandelion seed head
This change in the collective instinct of people has come about through successive generations becoming more urbanised with less plant interaction such as blowing a dandelion seed head, throwing a grass seed dart, eating wild blackberries or sticking cleavers to jumpers; children still do this but there are many who don’t and lose a connection with the plant world. The result of this is that education reduces the amount of plant learning, and in biology courses there is a main focus on the animal kingdom; there is a perceived lack of interest in the plant world. Things have become so bad that the Oxford Junior Dictionary removed words like ‘acorn’ and ‘buttercup’ preferring instead ‘broadband’ and ‘cut and paste’; they were seen as no longer relevant to a child’s life.
University of Bristol Botanic Garden
There is however, a great appetite among young people to be green, to recycle and mend the excesses of the generations that went before them; often students tell me it’s the biggest issue for them and they’d like to make a difference. How is a difference made? I think we can all make a simple difference by introducing plants to friends and relatives, opening eyes to the trees and weeds and the force of life going on around us and under our feet. It could be argued that many of the world’s problems can be solved with plants; forests, food, habitats are all areas that need experts, and while there are many graduates of zoology degrees there are few from plant sciences. This is changing with Universities now offering full plant science degrees; there are many jobs in plant sciences as governments and companies are beginning to see how important it is. Bristol University is launching a plant science degree starting in September 2019 based in the magnificent Life Sciences building with a group of world experts in the field of plant science. Of course, undergraduates will use the Botanic Garden as a second home and have access to all our knowledge and experience, we’re really looking forward to it. If you, a relative, son or daughter are interested click here to view the degree.
We all have a role to play in protecting our relationship with the natural world which can be played by simply talking about the plants we see to people. I’m always disposed to optimism and today’s

young people seem to be committed to green ways; this problem arose through successive generations and perhaps it can be cured in the same way, the passing down of knowledge as we go.

By Andy Winfield

Native American foods

Posted on by andy.winfield
By Claire Cope

Having worked as a trainee at the Botanic Garden for nearly two years I am now coming to the end of my time with the garden. I have learned more than I thought possible to learn in just two years, have gained my RHS qualifications, have had the opportunity to work with an amazing range of plants and have acquired a huge amount of practical horticultural experience. Best of all, I have had the opportunity to work alongside some very wonderful people who have shared their knowledge and passion with me and have made me feel very welcomed into this beautiful community. 


In terms of my horticultural work here at the garden, my favourite part of this last year has been my project to work on the Native American Vegetable display. This included everything from designing the planting lay out, propagating and maintaining the plants, through to harvesting the food and collecting the seeds. Therefore, for this article I want to share with you some of the fascinating information I’ve learnt about this amazing group of plants.

Firstly, I had no idea that so much of our food originated in South America and has

Squash originated in South America and was one
of the ‘three sisters’.

been being cultivated for so many years. Many plants that today we consider as staples such as tomatoes, potatoes, beans, corn, squash, and peppers were originally cultivated thousands of years ago by native civilisations such as the Inca, Maya and Aztec peoples.


In North and Central America, prior to the European invasions, it was the three crops – Sweetcorn, Beans and Squash that formed the foundation of sustainable subsistence agriculture.  These crops became known as ‘The Three Sisters’ and were grown as companion plants where the tall stems of the sweetcorn support the climbing beans, the beans fix nitrogen into the soil to feed the hungry squash which in turn provides a living mulch to suppress weeds and shade the ground for the corn. Unfortunately, due to the differences in climate and the need to protect the corn from the badgers, we weren’t able to replicate this exactly but I made these three plants the centre of the display in order to tell the story of the three sisters and to show how these ancient cultures had devised methods to work with the plants and with natural systems to increase productivity …. Unfortunately, the pesky squirrels feasted on all of our tasty corn kernels but we did get some lovely large squash and lots of purple beans!

Quinoa
The next thing that I found exciting to grow was the more unusual range of plants that were grown in cultivation so long ago but are only just coming into popularity now such as Quinoa. This plant is grown for its grain which is high in protein and was originally domesticated by the Andean people over 3000 years ago! The Incas held this crop as sacred and referred to it as chisoya mama meaning ‘mother of all grains’. We grew two different cultivars of Chenopodium quinoa – The first ’Quinoa’ was the more common form and the second ‘Huauzontle’ is the lesser known and is primarily grown for the immature seed-heads which can be eaten as a vegetable like broccoli. This form grew extremely tall and bushy and by October it was looking very beautiful with its pink- burgundy seed heads.   

There were also plants in this display that were more unusual and some I hadn’t heard

Cyclanthera pedata

of before which have the potential to be incorporated into western food production in the future. For instance – I really enjoyed growing the Cyclanthera pedata ‘Fat Baby’ and ‘Bolivian Giant’. These were vigorous climbers which produced very strange spikey green fruits which tasted just like a cucumber!


Then there were plants that I had always considered as ornamentals which I can now look at in a new light – such as the Dahlias with their edible tubers, Lupins with their edible beans and Nasturtium with edible leaves and flowers.

Some of the cultivars chosen for the display had really interesting stories – for example the beans we grew, Phaseolus vulgaris ’Cherokee trail of tears’, were originally from the native American Cherokee people who were driven out of their homelands by European settlers – a forced march know as ‘Trail of Tears’. This bean was one of their heirlooms which has been passed from generation to generation ever since.


We are now coming to the end of the season and soon the bed will be nearly empty again and ready for the next trainee to start all over again! What a great project to have been given, I have learnt so much and hope that those of you who saw it enjoyed the display!

Gardening keeps us grounded

Posted on by andy.winfield

By Helen Roberts

Sir David Attenborough once said:

Connect with Nature in any way you can. Contact with the natural world isn’t a luxury – it is actually a necessity for all of us. All we know about the natural world gives us pleasure, delight, expertise, continuous interest throughout the year – joy on many occasions and solace on sad ones. Knowing about the natural world and being in contact with it is the most precious inheritance that human beings can have.

Even containers in small spaces help make a
connection with nature. 

It is the word ‘connect’ that is so fundamentally important in a world that often feels to many people fraught, pressured and tiring. In the ever-stressful environments that humans have to confront, be it at work or home, working in gardens for many is a tonic and a way to reconnect with the landscape. For many it brings peace, a space in which to reflect and feel restored. The physicality of gardening is not only good for the body, it is good for the soul too.

This week is Mental Health Awareness Week; a campaign set up and run by the charity the Mental Health Foundation. People across the nation will get together to discuss mental health through various activities, events, talks and sharing of stories. The theme this year is ‘Surviving or Thriving’ and seeks to look at why so few people are thriving with good mental health. The lovely illustration depicting this year’s theme is rather apt, it shows a tree or shrub growing through the words ‘surviving or thriving’. Gardening undoubtedly can make you thrive on many different levels and it certainly fulfils at least 8 out of the top 10 tips listed on the charity’s website on how to look after your own mental health.
I have seen the benefits that gardening can have on mental health through my work and teaching in horticulture. It can clearly turn people’s lives around, almost like a reset button to recharge and move positively forwards. It helps to build confidence, a sense of worth and forges new friendships and all of this happening as people begin to develop a lifelong love of gardening.
Gardening keeps you active physically, but once you get the gardening ‘bug’ it is mentally energising too. Gardening is both stimulating and relaxing (unless you are digging out a tree stump) and with it comes either peacefulness if working on one’s own or, if working with others, calm chatter. Some people loathe weeding, but I know of a great many who love it either because they can just concentrate entirely on the task at hand (like a form of horticultural meditation) or they get some good thinking done. I think some of my better ideas for writing have come to me when I have been weeding.
With regards to feeding the body, gardening to grow vegetables often means you eat well and nothing tastes better than home-grown produce. I think that people are more likely to eat healthily if they know that what they are about to eat they have put the effort into producing. As a child growing up with access to a family allotment, I was much more willing to ‘try’ a vegetable if it was something that I had grown. So in that sense it makes people more adventurous in their diet and variety is good for healthy eating.
Many of us do not have gardens big enough to grow our own food, and this could be viewed as unfortunate. But as we turn to allotments and community gardens to grow food, we find opportunities to not only reconnect with the landscape, but with people with whom we share at least one shared passion. It is an opportunity to step out of the digital confines of social media and meet with people face-to-face, or at the very least, work peacefully alongside each other in silent companionship.
One of the truly great things about gardening is that it helps to remove boundaries of age, gender and background; if you have an interest in it, then the margins of society that so often leave us feeling alienated and alone are removed. I personally have gardening friends from all walks of life, ranging in age from their twenties into their eighties. Gardening definitely has no barriers and it can be refreshing to meet people who can offer a different perspective or solution on matters (maybe not even related to horticulture). If you have a passion for gardening then you will find others that feel the same. If you garden because you love doing it, then that in itself will make you feel good, both in body and in mind.
In 2013, a review of all the scientific studies of gardening-based mental health interventions found that there was convincing evidence of its benefits. There were reduced symptoms of depression and anxiety and participants described many different emotional, physical, vocational, social and spiritual benefits. In 2015, the JointCommissioning Panel for Mental Health and the Centre for Sustainable Healthcarereleased a guidance document for commissioners of financially, environmentally, and socially sustainable mental health services. The guidance recommends horticulture therapy as an effective, sustainable and resilient intervention to promote mental health.

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.
Important links:

The wondrous creatures that share our gardens part I: The creepy crawlies

Posted on by andy.winfield

By Alida Robey


As I peacefully garden, random thoughts about the wildlife I encounter waft through my head. How far does a hedgehog travel in a night? If you throw a snail over the fence, is it likely to find its way back into the garden? How long do worms live?  Rather than continue repeating this cycle of speculation,  I decided to get to the bottom of these little mysteries.

Do those snails make it back over the fence?

There are 43,000 species of Gastropoda (the taxonomic group better known as slugs and snails). There are 220 non-marine species of these mucous crawling critters living in the UK, so it’s small wonder we have such problems with snails in our gardens. Snails can live up to three years. Each snail has both male and female sex organs (they are hermaphrodites) and mating occurs when two entwined snails each shoots a small sperm-carrying dart at the other; each then goes off to lay about 40 eggs.
Garden snail.
Photo credit: Daniela [via Flickr, CC license]
And that burning question….what happens to all those snails that I catapult over my fence? Well yes, snails can happily find their way back over fences and walls, up to a distance of 10 metres. Professor Dave Hodgson, Professor of Ecology, University of Exeter, revealed this fact when he used LED lights and UV paint to track the movement of snails at night in a British garden. The study revealed that snails can travel distances of up to 25 metres during a 24-hour period and reach top speeds of one metre per hour. So you will need to do more than lob them discretely over the wall if you are hoping to do more than just make them work a bit harder for their supper! 

What is the lifespan of a slug?

Most slugs evolved from snails, losing their shells through evolutionary processes over time.
Depending on the species, slugs can live between 1 and 5 years. If you are squeamish about slugs, count your blessings you don’t live in North America where there is the banana slug, which grows to 10 inches long!
The banana slug (Ariolimax columbianus).
Photo credit: Oregon Department of Agriculture [via Flickr, CC license]
Much as we may berate slugs, they do serve an important function in nature, munching up rotting debris and recycling the nutrients back into the food chain. 
However, they also like to munch the tender leaves and stalks of our most treasured little seedlings, and it is for this reason that many British gardeners are keen to shorten the lifespan of these troublesome pests. Use of slug baits is highly controversial and there is insubstantial and conflicting information regarding how these poisons affect other creatures, such as birds and hedgehogs, which are natural predators of slugs. 
Despite being in widespread use, slug pellets are considered by some to be a relatively ineffective method of slug control, some say killing no more than 10% of the slug population in the average garden. Slug pellets fall into 2 main types; those containing metaldehyde or the less common methiocarb.
Metaldehyde is the most common and less toxic form of slug poison and if not taken in too large quantities less likely than methiocarb products to be fatal to other animals – the suggested dose being one pellet every 10 cm (4”). 
Methiocarb is about ten times more poisonous than metaldehyde, and therefore of greater danger to other animals. It breaks down more slowly too, making it a longer lasting hazard in the environment with the potential to affect more animals (targeted or not).
The RHS has some research underway that is due to report in December 2017 on the relative effectiveness of different methods of slug and snail control, including the use of nematodes. This research will help them improve their advice about slug and snail control. 

Does cutting a worm in half make 2 worms?

Sadly no – but thankfully at least one half should still survive. 
Earthworms
Photo credit: Wormwould [via Flickr CC by-NC 2.0]
I always say the common earthworm is the hardest worker in the garden, and Charles Darwin called them ‘nature’s ploughs’. They do an extraordinary job of aerating and fertilising the soil, pulling leaves down beneath the ground at a rapid rate and bringing valuable minerals to the surface with their wormcasts. One acre of land can hold around 3 million earthworms, which are capable of bringing around 9 tonnes of soil to the surface through their wormcasts in just one year. The tunnels they make and live in can go as deep as 1.8 m (6 ft), which enables them to find moisture in times of drought. Worms are capable of digesting even leaves that are generally poisonous, owing to the presence of a chemical in their gut called drilodefensins. Scientists at University College London identified this molecule, which breaks down the toxic chemicals plants produce to deter herbivores. Without this ability, leaves would pile up on the surface of the soil.

Ladybirds
Photo credit: danielweiresq
[via Flickr CC by-NC 2.0]

How many spots does a ladybird have? 

Well, actually, there are 40 different species of ladybirds in Britain, with differing numbers of spots and some have yellow wing cases rather than red – the invasive harlequin ladybird (Harmonia axyridis) can also have a black wing case. And no, ladybirds do not gain more spots as they get older. The ladybird is a most welcome addition to the garden as its larvae munch their way through vast quantities of aphids prior to pupating.  However, they have to eat heartily as aphids are so fast at reproducing, they get through three generations for every single generation of ladybird. For this reason, the ladybird’s ability to truly help control aphid infestations has been brought into question.

Is the common wood lice harmful to plants?

An unfortunate name for a little creature that is more closely related (admittedly from way back), to crabs and lobsters! It quietly beavers away eating rotten wood, fungi and garden debris and protects itself from drying up by only coming out from under stones and logs at night. 
Woodlice
Photo credit: Mark Hilditch [via Flickr CC by-NC 2.0]
Woodlice cause little or no damage to plants. Large numbers can be found in compost heaps, where they help break down the plant material and are a useful part of the composting process. But you may well have seen what you think is the same thing around your house. This is a slightly different species of wood louse to the garden variety and is called the pill bug.  It can be distinguished from the woodlouse by its tendency to roll into a tight ball when threatened. Pill bugs are not thought to do any harm in the house although their presence may indicate an issue with dampness, as this is their preferred environment.

How can you tell  the difference between toads and frogs?

I have often wondered how to tell which was which. Frogs generally have a wet, smoother skin, while that of toads is dry and ‘warty.’ Toads walk rather than leap and are less nimble movers than frogs. I regularly help with a garden in Herefordshire where I am frequently surprised by the lump of soil that turns out to be a toad that then ambles off unsteadily down the garden – a frog would have leapt off at the least disturbance. 
Toads return each year to the same pond to spawn their eggs – as many as 7,000 in a sitting.
Frogs come in a much wider range of colours than the steady brown toad with its darker brown blotches; they can be anything from yellow, brown, orange, red, grey, and different shades of speckling. 

What ARE Nematodes?

Caenorhabditis elegans is a nematode that is studied
extensively by scientists.
Photo credit:snickclunk [via Flickr CC by-NC 2.0]
Nematodes are microscopic worms that are naturally present in the soil. They can be purchased in concentrated volumes as biological pest control. There are specific nematodes for each different  garden ‘pest’ such as slugs, vine weevils, ants, chafer grubs, leatherjackets, caterpillars, codling moth etc. An advantage of nematodes is that they don’t persist in the environment like chemicals do – when their prey item depletes, they naturally die off to natural population levels. 
As this is a ‘live’ product, it is currently only available from online suppliers as nematodes have to be used within a few days of purchase. They are sent in a little pack that resembles fresh yeast and one simply has to dilute this to the required level and then water them into the garden. I have used nematodes myself very successfully and believe that with increasing regulatory pressure on toxic sprays and treatments that are harmful to pollinators and other wildlife, nematodes are the way of the future for pest control.
Please leave a comment if you have any questions about the wildlife you encounter in your garden and we’ll do our very best to find an answer. Part 2 will have some common questions about our furred and feathered garden friends.
Alida Robey has a small gardening business in Bristol. For several years in New Zealand she worked with others to support projects to establish composting on both domestic and a ‘city-to-farm’ basis. 

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

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 

Why Garden?

Posted on by andy.winfield

By Helen Roberts

Monty Don’s visit in July to the University of Bristol Botanic Garden did not disappoint. He delivered two lectures entitled ‘Why Garden’, one in the morning and one in the afternoon, with lunch and a tour of the garden in between. The subject of why to garden is vast and could be approached from a multitude of angles . However, Monty used his personal experiences in working his garden of Longmeadow to discuss how gardening can bring both restoration of the mind and body to people, as well as a reconnection to the landscape.
                                                      
Monty first began gardening because of his mother, but back then it was a chore to be got through, simply a means to an end. She would frequently use the phrase, “…and what are you doing this afternoon?”, which meant “you had better get on with the gardening!” By the age of 17, Monty had a rudimentary knowledge of gardening and was looking after a half-acre vegetable garden.
His first realisation that gardening was what he wanted to do was when he was back home from school and he was sowing carrots in the garden. He described to the audience that in that moment he felt singular happiness. He felt deeply rested and contented.

Connecting to nature 

I could relate to Monty’s words as I feel the same whenever I am in my garden. I feel peaceful and relaxed even if what I am doing could be physically exerting, like digging. I sense a reconnection with the garden and the landscape around me (farming is in my blood so I guess that connection is somehow re-established when I garden).
When I return home from a trip away, those first glimpses from the Mendips across Somerset stir a deep sense of belonging to this landscape.  Hardy’s description of the Vale of Blackmoor in Tess of the D’urbervilles(although relating to country south of where I live) perfectly describes to me the colours and textures of where I live at the foot of the Mendips, the same vivid blue and soft haze with its intricate network of fields. His description describes to me the landscape of home and attachment.
“..the fields are mere paddocks, so reduced that from this height their hedgerows appear a network of dark green threads overspreading the paler green of the grass. The atmosphere beneath is languorous, and is so tinged with azure that what artists call the middle distance partakes also of that hue, while the horizon beyond is of the deepest ultramarine.”
Panorama of the mendips taken from Durston Drove above Wells.
Photo credit Stewart Black, [via Flickr Creative Commons 2.0]
In today’s society, people are losing their connections to nature and to the non-urban landscape – particularly children. The NationalTrust produced a report on the topic of Nature Deficit Disorder in children and how to address it. Richard Louv also discusses this in great detail in his book, Last Child in the Woods.
There is a real and absolute need to reconnect with our natural world – not only to save it, but to save ourselves. Studies published in 2014, in the journal Environment and Behaviour, showed that our emotional connections with nature influence choices of living sustainably, but also showed there was a connection between exposure to nature and our own happiness.

Finding refuge in the garden – physically and mentally

For Monty, gardening has always been a reconnection to the landscape, to restore balance and order in his (by his own admission) sometimes disordered and chaotic mind. He shared with the audience that after suffering from depression in the 1980s, returning to the garden brought about his recovery and the restoration of his mind. His garden was his refuge.
“In this age of anxiety gardens are a refuge,” Monty explained, “a safe haven from the stresses of everyday life. A garden never lies; you can trust it and it will respond to you. They are ever present and throughout the course of the seasons it will always return, offering both familiarity and stability.”
Not everyone has their own personal garden. The University of Bristol Botanic Garden offers a place for people to reconnect with the natural world and to learn about local plants as well as more exotic ones. It is a plant-packed green sanctuary in the heart of Bristol. The gardens themselves open our minds to the huge diversity and importance of plants. And they are in a constant state of flux, changing over time, as gardens and landscapes tend to do.
Monty spoke about learning from other gardens to gain ideas and inspiration and soak up knowledge from those who work there. I frequently explore different gardens and I take my children with me. They are not bored by plants and gardens. They run around and explore. They discover and forage. They are connecting to the plants and animals – whether it’s watching water boatmen in a pond or looking at the rocks and crevices in a wall.
I was visiting a garden the other day, and I was watching my 4-year old as he walked along a flower border gently touching and feeling different plants, such as the beautiful flowers of the paper-thin Papaver rhoeas and the fluffy fox-like tails of Hordeum jubatum. I bought seed after that visit because I wanted to recreate that sense for my children in my own garden.
Monty said, “when you garden you are building the story of your life.” The Botanic Garden is doing just that. It is evolving and as it changes the imprints of those who have been involved are left behind. Creating a rich and dynamic place to explore, learn and reconnect with the natural world.

Raising the ‘green’ roof

Posted on by andy.winfield

By Helen Roberts


We currently have a real shortage of housing in the UK and the estate agency Savills has estimated that there will be a shortfall of 160,000 homes in the next five years unless local authorities act. With this in mind, I started thinking of the building industry and how sustain­­able building design has become increasingly important over the last few decades. Not only does the industry consider the sustainability of the materials themselves, but designs aim to reduce consumption of non-renewable resources and minimize waste during and after the life of the building, while creating a healthy and comfortable environment for the occupants.

Within the field of sustainable building design is the subject of green roofs. This is an area of design that holds great interest to me, as I am a landscape architect with previous training in plant sciences. Green roofs play a pivotal role in urban environments by reducing rainwater runoff, reducing energy consumption for heating and cooling, heat island mitigation, creating valuable wildlife habitats and also making an aesthetically pleasant landscape for people to escape from the urban environment. 

What is a green roof?

Green roof on Chicago City Hall. Photo credit: TonyTheTiger
[CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)
via Wikimedia Commons

A green roof is a platform or roof on which vegetation is grown or wildlife habitats are created. The basic elements include a waterproofing membrane covered with a growing medium and vegetation. The design, ecology and aesthetics of a green roof can vary considerably, however, and can be adapted specifically to suit a particular location or design brief. Plants in containers on a roof top are not considered to be a true green roof.
The term green roof, however, can also be used to describe roofs that incorporate green technology, such as solar thermal collectors or photovoltaic (solar) panels.

The history of green roofs

Green roofs are not a new concept. Dwellings of the Neolithic period, such as the Neolithic village of Skara Brae in Orkney, are thought to have had turf roofs. The Hanging Gardens of Babylon, one of the wonders of the Ancient World, were extravagant green roof gardens, thought to be irrigated by about 35,000 litres of water brought in through aqueducts and canals.

The houses at Skara Brae, Orkney were thought to have
had turf roofs. Photo credit: Antony Slegg
[CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)],
via Wikimedia Commons

Turf or sod roofs were common centuries ago in Scandinavia and can still be seen in places like the Faroe Islands. I visited Lund, Sweden recently and saw beautiful turf roofed farmhouses in the museum of cultural history. The turf helped keep dwellings cool in the summer and warm in the winter. However, these structures would most likely have leaked and also would have had the inconvenience of burrowing wildlife!
Modern green roofs didn’t develop until the 1970s in Germany, when legislation was passed to encourage the introduction of green roofs. Unlike the historical turf roofs, modern green roof designs include drainage and root protection measures, as well as lightweight growing media.
The UK is somewhat behind continental Europe in terms of using government policy to implement green roof technology. But things are changing and there has been an increase in the use of green roof technology over the past decade. In fact, Bristol’s development policy (Bristol Development Framework Core Strategy; adopted in June 2011) encourages the incorporation of green roofs as a way of enhancing the biodiversity value of new building developments and views green roofs as an essential asset of the strategic green infrastructure network.Bristol  

Green roofs can be extensive, intensive or semi-intensive

Green roofs vary in ‘intensity’ in terms of the depth of substrate used and the level of maintenance needed, which affects the type of vegetation that can then be grown. A typical green roof will have, on top of the roof itself, a layer of waterproofing, a root barrier, protection/moisture retention matting, a drainage layer, a filter sheet, the growing substrate and then the plants. Green technology, such as solar panels, may also be incorporated into the design of the vegetated roof.
Green roofs are classified as extensive, intensive or semi-intensive in nature. Extensive green roofs are less than 100 mm deep and are relatively low maintenance. Their shallow depth means they are lighter but that they can support fewer vegetation types. This means they generally have lower biodiversity value and limited water holding capacity. Most people will be familiar with sedum matting as a common form of extensive green roof.

Construction layers of a green roof.
Photo credit: thingermejig (flickr.com)
[CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)],
via Wikimedia Commons

Semi intensive green roofs have substrate depths of about 100 mm to 200 mm, require moderate maintenance, can support a greater range of plant species and have the ability for rainwater attenuation.
Intensive green roofs have deeper substrates (over 200 mm) and therefore require more substantial structural support. The deep substrate can sustain more elaborate plantings, including many different tree and shrub species, which offers a more garden-like space for users. Intensive green roofs require more maintenance and complex drainage and irrigation systems, but can offer rainwater attenuation and a greater degree of species biodiversity.
The aim of the green roof will ultimately influence its design. If, for example, the aim is simply to have an insulating effect on the building, a low-maintenance extensive green roof with low-lying vegetation would probably be sufficient. If, however, the aim is to attract and enhance wildlife, an intensive design is likely required to support a diversity of plant species that can provide a variety of structure and microhabitats. I will discuss biodiversity and wildlife green roofs in more detail in my next blog post.


The benefits of green roofs:

Green roofs help improve the urban environment in many ways, from creating a natural space for office workers to enjoy to helping mitigate the urban heat island effect. Here are some of the benefits of green roofs:

Creating a biodiverse space and a relaxing place

Green roofs can increase biodiversity in urban areas where ground level space has been developed and valuable green corridors lost. Sky-high gardens can be important stepping stones for wildlife and can create habitat and forage for a variety of species, which wouldn’t exist with conventional roofs.
These places can also provide a haven for people to visit or to just view and offer a respite from a hard urban setting. 

Green roofs slow down runoff and help reduce flooding

There is a requirement now in the UK (under the Flood and Water Management Act 2010) that new developments mitigate storm water runoff and include appropriate water management systems. An established green roof can significantly reduce the peak flow rates and total volume of water runoff. Water is stored by the plants and substrate and is released back slowly into the atmosphere by evapotranspiration and evaporation. The plants also help filter out pollutants in the rainfall.
Many features of Sustainable Urban Drainage Systems (SUDS), such as permeable surfaces and swales, are not easily incorporated into a hard urban and so green roofs are considered a good solution to reducing storm water runoff. Interestingly, it has been found that in the summer 70-80% of rainfall can be retained in a green roof and in winter 10-35% (due to differences in evapotranspiration in summer and winter). 

The cool down effect of green roofs

Urban areas that are hotter than nearby rural areas are described as heat islands. The additional heat means more energy is used in summer for cooling (air conditioning and refrigeration), there are more incidents of heat-related illness and mortality and there are implications for air and water quality. Green roofs help improve local air quality and cool the urban environment by reflecting more of the sun’s rays compared with conventional roofs. The plants shade and insulate the underlying roof and have a cooling effect as water is released through evapotranspiration and evaporation – the building equivalent of sweating.

Green roofs reduce energy consumption

The thermal insulation properties of green roofs reduce the need for air conditioning in summer and heating in winter, decreasing associated emissions and dependence on non-renewable resources. 

Green roof allotments

There is increasing interest in the use of green roofs for food production and this ties in closely with the provision of amenity space. There is limited green space that can be used at ground level for food production in urban areas, so the logical step is to go up!. Roof-top allotments reduce food transportation and help increase the supply where the demand exists. For the individual household, it can help reduce food costs and provide many benefits associated with growing your own food. For a community, rooftop gardens can become a centre for social cohesion.
Though there are examples of agri-roofs, mainly in Asia, the use of roofs for food production is relatively unexplored and will provide ‘food for thought’ in the design of future green roofs.

Raise the roof on green roofs

With their many benefits, green roofs are likely to become a vital component of building designs in the future. New developments are imminent in the face of a housing shortage and green roofs offer an opportunity to improve the urban landscape, providing habitat for essential species, such as pollinators, and potentially helping respond to challenges with food security. Green space that is lost on the ground needs to be created up above with the transformation of featureless barren roofs into beautiful diverse green places. 

We’re gardenin’ in the rain

Posted on by andy.winfield

By Helen Roberts


It has been unbelievably wet since the start of 2014 with England experiencing it’s wettest January since records began over 100 years ago. The Somerset levels have suffered dreadfully and huge areas are still underwater and are likely to remain so for weeks or even months to come. From where I live, on the Mendips, I have far-reaching views over to Glastonbury Tor and the Quantocks and the area of levels in between looks like the vast inland sea it once was. In most other areas, the ground is completely saturated and in some places water is bubbling up to the surface.

Flooding in Greylake, Somerset in February, 2014. Photo
courtesy of Live-vibe on Flickr CC. 

What does waterlogging do to our gardens and what can we do to solve it?


Many plants do not like to be waterlogged because their roots need oxygen as well as water and nutrients. When roots are starved of oxygen they die and these dead roots can then act as a host for fungi such as Phytophthora, a root rot. Shrubs and fruit trees are particularly vulnerable to waterlogging as they cannot put on new roots as quickly as perennials and cannot stand long periods under water. Add freezing conditions with waterlogging and your plants may be in big trouble.
Winter flooding may not be fatal though, as many plants can experience and survive winter flooding for short periods of time. You can give your plants a helping hand if they’re waterlogged by pruning ornamentals right back so that they don’t have to protect so much above ground. You can also remove any dead or dying shoots and take cuttings as a back-up should the plant die. Smaller plants can be transplanted into pots with fresh compost, removing dead roots before transplanting.
Looking after waterlogged lawns is a different matter. If your lawn is squelchy to walk on at the moment, try to stay off it. Walking on it will only aid compaction and make matters worse. Waterlogged lawns can quickly lead to the grass dying and moss, algae, lichens and liverworts taking over. I do not have an issue with these plants in a lawn per se and I am not one to fret over weeds in a lawn either, but if you do want to make things better and improve a waterlogged lawn there are a number of options.

You can try pricking, spiking or slitting the surface of the lawn with powered tools or even a fork. This leaves holes that can be infilled with lawn top dressings or horticultural sand. It is best to get rid of surface water first, if possible, by sweeping it off with a brush into the borders. Otherwise, wait for it to drain naturally. Alternatively, convert your lawn into a water meadow!

Create a partnership with nature


Sometimes struggling against waterlogging in your garden or parts of your garden is a losing battle. It is simply better to accept the natural conditions of your garden and work with what you have. Rethink your palette of plants and cultivate those that favour wet soil. If the ground is permanently wet, consider establishing a bog garden as bog plants can be truly architectural in their habit and are excellent for attracting wildlife.

Some suitable bog species suggested by the RHS website include:
Herbaceous perennials: Bog primulas, Eupatorium maculatum Atropurpureum Group, Darmera peltata,Iris ensata ‘Rose Queen’, Iris laevigata, Ligularia ‘The Rocket’, Lobelia cardinalis, Rodgersia pinnata‘Superba’, Trollius x cultorum ‘Superbus’
Grasses: Spartina pectinata ‘Aureomarginata’, Carex elata ‘Aurea’
Ferns: Athyrium filix-femina, Matteuccia struthiopteris

A sustainable approach to managing flooding

How we manage water and excessive water in our own gardens, particularly in urban areas where there is nowhere to drain excess water, is very relevant at present considering the amount of rainfall we have had over the last couple of months.
Sustainable urban drainage systems or SuDS are approaches of managing surface waters taking into account quantity (flooding), quality (pollution) and amenity issues of water. They ultimately contribute to sustainable development and improve urban design. These systems mimic nature and manage rainfall as close as possible to where it falls aiming to slow water down before it enters watercourses. This is basically done by forming structures and landforms that can store water and allow water to soak into the ground, evaporated from surface water or lost through evapotranspiration. 

The use of SuDS is not by any means a new concept to ecologists, engineers, architects and landscape architects. It has been implemented very successfully worldwide and been effective in its way of managing water but also contributing significantly to the production of some truly innovative and outstanding design as well as creating areas of ecological value.

So how can you manage rainwater on a smaller scale in your own garden?

Nigel Dunnett, Professor of Planting Design and Vegetation Technology, and Director of the Green Roof Centre at the University of Sheffield is an expert in rain gardens and small scale rainwater management features. His research has looked at innovative approaches in planting design and landscaping that serve to store, collect and infiltrate rainwater runoff. Examples include the use of storm water or through flow planters, which are essentially raised, planted beds at the base of buildings that can take runoff water directly from roofs or adjacent areas of hardstanding.
The key to Dunnett’s research is that it can be replicated on a small scale in one’s own garden and can be just as effective in terms of its aesthetic and ecological value, particularly in urban areas.
Other approaches to managing rainwater include reducing runoff from hard surfaces, such as driveways and patios, by using permeable paving that allows water to soak directly into the ground. Roofs on sheds and garages or any external outbuildings in the garden could have green roofs installed. Furthermore, you could use Dunnett’s techniques of creating rain gardens and create a truly sustainable garden that works with nature and not against it.
Nigel Dunnett was a recent speaker with the University of Bristol Botanic Garden Friends’ Lecture series.