Growing Up the Wall

How to Grow Food in Vertical Places, on Roofs and in Small Spaces

By Sue Fisher

UIT Cambridge Ltd

Copyright © 2013 Sue Fisher
All rights reserved.
ISBN: 978-0-85784-109-4

Contents

Dedication,
Acknowledgements,
Introduction,
PART 1: Planning your space,
1. Practicalities,
2. Edible living walls,
3. Green roofs,
4. Larger containers for small spaces,
5. Choosing your plants,
PART 2: Plant directory,
6. Vegetables,
7. Fruit,
8. Herbs,
9. Edible flowers,
Resources,
Index,
Copyright,

CHAPTER 1

Practicalities

Growing upwards on the vertical – as well as on roofs – offers incredible possibilities for the wealth of places where ground space is severely limited or downright non-existent. However, regardless of whether you have just gained a new outside area and want to start growing things to eat, or have been inspired to a new direction for an existing spot, some initial site assessment and planning is crucial to success.

While any form of small-space gardening benefits from planning to effectively squeeze the proverbial quart into a pint pot, this assumes even greater importance when growing in any sites where there are safety and structural implications. The actual growing of your crops is something well worth considering at this early stage too: the practical nitty-gritty of how to water, care for, harvest and manage plants in containers or raised on high, year on year. Gaining a clear view now of the way you will garden is likely to avoid sowing the seeds of disappointment for the future. If you’re a first-time gardener, flick to the end of this chapter, where there are some useful guidelines on getting started.

Making the most of your space

This newer approach to gardening, not only upwards but on roofs too, will help you make the most of every surface in ways you may never have thought possible.

A good place to start can be a brainstorming session: standing back and taking a long, critical look at whatever space you have at your disposal. While I’m not a great advocate of gardening by committee, this can be a good approach when trying to think outside the ‘traditional gardening’ box. For example, someone who is a keen DIY enthusiast or salvager of discarded materials may be able to envisage many creative possibilities. If you are trying to design a school or community space, maybe even consider having a ‘planning party’: this suggestion is inspired by a comment from Tim Smit, founder of the Eden Project, that many of the founding groups’ best ideas were produced by ‘wine light’! Whether you’re working alone or in a group, at this early stage it’s important to jot down every idea, however wacky – bearing in mind that many of the vertical and roof-growing schemes in existence today would have been thought impossibly futuristic just a few years ago.

Almost every living environment, be it a home garden, balcony, apartment roof, school, or community space, is likely to have lots of outdoor verticals. Put together, all these sites have immense possibilities for growing a feast. Much of this is thanks to the living wall and roof technology which is a massive leap forward from the traditional approach that limited gardeners to growing climbing plants in the ground, or in containers such as hanging baskets or window boxes. However, do consider ‘traditional’ methods as well, maybe combining the two to get the best of both worlds and to really maximise the cropping potential from your outdoor space.

Potential growing spaces include:

• House or apartment walls. Every building has strong walls that have huge potential for growing crops, either on the walls themselves or, in the case of climbers and tall plants, grown at the base and trained upwards.

• Boundary walls and fences. Growing plants on the vertical is not only a brilliant space-saver but is often a useful green cover-up for structures that are less than attractive.

• Garden buildings. Garages, sheds, bike and garden stores have lots of growing potential not just on their sides but roofs too, so long as the structure is sufficiently strong or can be made so.

• Out-of-sight roofs. Home extensions, garages and other buildings may have roofs with planting possibilities (for more on roof practicalities see page 98).

Assessing your site

The practicalities, along with the pros and cons, of living walls and green roofs are covered in more detail in Chapters 2 and 3. The following is a brief overview of the main points relating to both.

Planning

Urban planners are broadly very much in favour of ‘green’ features; indeed with new-build applications or building conversions, an eco-friendly green roof, for example, may well tip the balance in terms of whether the planning authority takes a favourable view or not. While small-scale features, particularly retrofitted ones, are unlikely to need planning consent, when in doubt do check with just a quick phone call or email to the planning department of your local council.

Landlord or owner consent

If you do not actually own a building, or the boundary wall or fence that you’re eyeing with interest, it is essential to get permission from the owner before starting to construct anything like a living wall or roof that will form a major feature. If you own your home, the title deeds should clarify the ownership of the boundaries. However, even when you own the site, if your neighbour is likely to be affected in any way, do have an informal word with him or her first for the sake of peaceful relations – it could avoid an enormous amount of hassle and years of bad feeling. This is vital if you want to create a feature that would be overlooking someone else’s home or outdoor space, such as turning a flat roof into a green roof garden or building a high deck to make a garden platform. The old saying ‘good fences make good neighbours’ could be adapted in this case to ‘a bit of privacy makes for peaceful relations’.

Safety

Once you leave ground level in any way and particularly if going on to a roof, safety must be absolutely and totally paramount. A green roof that will be walked on, or a roof garden, simply must have a secure barrier around the edge. If your mode of access to a wall-growing or roof-growing space is via a set of steps or a ladder, the base and top must have secure spots on which to rest, and ideally be secured there too – even if just with removable wire loops, or hooks. If there are children of any age around, bear in mind that they are likely to find ladders irresistible to climb so safety is doubly important. Be aware that visiting children need even more supervision as they won’t be as familiar with the site and any potential dangers as resident children are. The ideal is a permanent stairway, with non-slip treads and a handrail, and which can be fitted with a safety gate if there are very young children around.

Structural stability and waterproofing

When constructing a green roof or attaching containers of any sort to a wall, there must be no danger of this causing any damage whatsoever, either by the weight causing physical damage, by water seepage down through a roof, or by the method of attachment piercing a protective coating such as render or plaster. Always bear in mind that plants + growing medium + water can add up to a considerable weight. When growing plants on roofs, it may be necessary to install a root barrier membrane as well as a waterproofing layer, to prevent roots questing down and working their way into the roof itself.

Ease of access

This may be stating the blindingly obvious, but only grow crop plants if you can actually access the area safely to maintain, water and harvest them. If a site can be accessed, but perhaps not quickly or easily, choose crops that aren’t so demanding of regular care and attention – garlic, carrots and herbs rather than tomatoes and beans, for example.

Water

A regular supply of water is absolutely essential, as plants on a roof or a sunny wall or fence will dry out rapidly. The ideal, from an eco-friendly and a cost point of view, is rainwater. This can be stored in a variety of ways, from traditional water butts to built-in underground storage chambers (see pages 38- 41). Some form of access to mains water is advisable as a backup, though, for times when stored supplies run dry. However, if lack of water is likely to be an issue, there are many herbs and edible flowers that are tolerant of drier conditions.

Cost

There are various ways of using containers and putting them together to make living wall growing solutions that can be created inexpensively by various DIY methods, and large-scale manufactured wall units and green roofs do not come cheap. In the case of green roofs, unless you are an ardent and capable DIY enthusiast, the larger roofs are best installed by professionals, which can be particularly costly. However, small-scale green roofs on buildings such as sheds, car ports, bicycle shelters, even chicken and animal runs, lend themselves much more readily to a DIY approach and hence are much cheaper to construct (see page 96).

Planning your planting

Every site will have its pros and cons for planting, mostly related to mini-microclimates that are subject to sun or shade, wind or drought, so the advantage of planning is to make the very most of what you have. A good place to start your planning is with old-fashioned pencil and paper to make a rough sketch of your site. Techies are likely to prefer the computer-aided approach, while a good way to plan that falls between these two methods is to photograph your space, print an enlargement and use an overlay of tracing paper for making notes.

Sun

Most important, because you simply can’t change this one! The vast majority of cropping plants need at least several hours of sun a day in order to thrive and produce a worthwhile crop. Note down where the sun shines, for roughly how long and at what time of day – bearing in mind that this will vary hugely at different times of year, as the sun is highest in the sky during summer. A compass to determine direction is a useful aid but remember that small spaces will be strongly influenced by factors such as nearby buildings, overhanging trees and the like.

Wind

Become familiar with where the wind blows: one side of a building may be snugly sheltered from the prevailing breeze, but go round a corner or through a gate and it could change to a howling gale. As with sunshine, wind varies with the seasons – a gentle, pleasant breeze in summer can become an Arctic blast in winter. Buildings, particularly tall ones, funnel the wind and a narrow street may well create a real ‘wind tunnel’ effect. Roofs are an especially harsh environment for plants in terms of exposure to wind. In many situations, however, you may be able to protect your growing environment by putting up screening of some type to filter or deflect the wind from your crops.

Indoor impacts

Don’t forget to consider any knock-on effect that your plans may have on your living space too; for example, a plant-covered pergola outside may seem like a great idea when summer sun creates a soft dappled shade, but could turn a room into a cold, shady cave in winter. However, your view from inside out can be greatly enhanced by growing plants on walls and fences that have previously been bleak and bare, so consider this aspect when choosing a location. One particular advantage of shallow wall containers such as troughs, hanging bags, window boxes and ready-made ‘living wall units’ (see page 55) is that these occupy very little depth, making it possible to plant space that is extremely restricted width-ways, such as along pathways or entrances.

Growing inside

Although food crops are usually thought of as almost exclusively outside, containers and wall units that are neat and non-drip are perfect for growing edible plants inside as well. Large plastic bottles are ideal for this purpose: they can be adapted into containers and used individually – the 5-litre (8¾ pint) size is good to use alone – or 2-litre (3½-pint) ones can be combined in a home-made frame (see page 77). There are ready-made units for indoor use too. Plenty of light is the one essential requirement; this could be in a porch, conservatory, a kitchen with large windows or roof lights, or even in a living room. However, now that low-energy LED lights are widely available, growing indoors with supplementary lighting is a feasible proposition even on a domestic scale. The fact that businesses such as Podponics in the USA (see Resources section) are growing a wealth of crops inside old shipping containers brings home the realisation that food really can be grown anywhere.

Take photographs

Lastly, do take plenty of photographs to begin with and as you progress: as your project develops, it’s a real morale-booster to look back on what you have achieved.

Growing practicalities

The smaller the space and the more restricted the growing area, the more it will pay to give plenty of attention to the basics, particularly on walls and roofs which can be more challenging places for plants to grow. Selecting the best compost or growing medium, regular watering and feeding, will all make an enormous difference to plant performance and hence the crops produced.

Choosing the right growing medium

A good foundation in which to grow is absolutely essential if fruit and vegetable plants are to perform well and produce a decent harvest. In traditional container growing this would mean simply buying a good-quality potting compost, and this is the case for small living wall and roof setups. However, for larger-scale installations weight is the overriding factor for obvious reasons: using soil or soil-based compost would result in ultra-heavy containers or wall units that would be hard if not impossible to attach securely, or roofs that would need to be substantially strengthened.

In addition to being lightweight, the medium in which plants are grown must also be good at retaining water and nutrients for vegetables and fruit, which mostly tend to be hungry and thirsty plants. The situation is different for a good proportion of herbs and edible flowers, many of which are tolerant of dry soils and a shallow growing medium. You can of course decide to do without soil altogether if you go for a soil-less or hydroponic growing system (see page 36).

Large green roofs have their own particular requirements, and commercial growing media or substrates have been developed specifically for them (see page 97).

Compost

There is an old gardening saying that ‘the answer lies in the soil’, and this is never truer than when growing plants where their rooting area is restricted. In order for plants to perform well, they simply need the best you can give. Always buy good-quality potting compost (cheaper in bulk if you need a lot), but never try to skimp and use alternatives. I’m often asked about using garden soil or used potting compost – the answer is a firm ‘no’ in both cases. Soil dug out of the garden or from the ground elsewhere is not only extremely heavy, but the physical structure just isn’t suited to growing in a very small space where roots need a carefully balanced structure with enough air spaces as well as a good nutritional balance. Potting compost that has been previously used is not only exhausted of nutrients but is likely to have degraded structurally too, and is likely to harbour pests, disease spores or weed seeds into the bargain.

Weight is usually the most important consideration with living walls, hanging or raised containers and containers on roofs, so avoid heavy soil (loam)-based compost such as the John Innes types and go for soil-less compost: this is the most widely available type and is usually labelled ‘multipurpose’. For environmental reasons I always prefer those based on recycled material rather than peat, although be sure to buy a good-quality brand as cheaper, inferior composts are sadly plentiful. In particular, be aware of those containing an abnormally high level of insufficiently rotted recycled green waste: this is likely to smell strongly when the bag is first opened and, because the woody material is too fresh, will draw nitrogen from the compost as it completes its breakdown process. Wherever weight is not an issue, and particularly if you want to grow long-lived crops (‘long’ as in more than a year, such as strawberries or berry fruits), it’s always worth using at least a proportion of soil-based compost. This performs better in the longer term, the loam providing more of a buffer against drought and being better at holding on to nutrients.

If you’re new to gardening, be aware that when going to a garden centre or store to buy compost you are likely to be faced with a bewildering range of different products in large and brightly coloured bags. Avoid anything labelled ‘soil conditioner’, ‘mulch’ or ‘composted manure’, all of which are designed for use in garden borders, not containers. ‘Potting compost’ is what you need for any form of container or restricted-space growing.

Two downsides of compost – and this will depend on the location of your growing site – is that it is (a) heavy and (b) bulky. Not a problem if you can unload a few bags from your car boot, or can receive a delivery, but potentially a large stumbling block if it needs to be carted up several flights of stairs or up on to a roof. If only a small amount is needed, buy blocks of dry, compacted coir compost, which swell up to a satisfying bulk when water is added. It’s more expensive than normal compost but the cost is balanced out by convenience.

(Continues…)Excerpted from Growing Up the Wall by Sue Fisher. Copyright © 2013 Sue Fisher. Excerpted by permission of UIT Cambridge Ltd.
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