Permaculture is the buzzword for sensible gardening, writes Jane Powers
There are a couple of kinds of gardening I have shied away from in this column, simply because they're too big to cram into a few hundred words. One subject that sprawls massively, eventually spreading its roots and branches into every aspect of life, is permaculture.
It is complicated to explain: if you ask five people what permaculture is, you'll get at least five different explanations. It is, in fact, a marvellously straightforward way of growing food - and, if you like, of leading your life. Permaculture - a contraction of "permanent", "agriculture" and, latterly, "culture" - has moved beyond the garden, and it now embraces architecture, ecological economics, social systems and just about anything else to do with human life.
But today let's stick with the garden, where it offers a method of growing things that is efficient and sustainable. In a nutshell, permaculture takes its systems from nature and tries to replicate them in the growing of food. It examines the relationships between all the elements in a garden (including the humans), and seeks to use them to maximise yield and minimise waste and energy expenditure.
I fear I haven't made myself clear, so I'll try again, with some examples and a little help.
"Permaculture," says Erik van Lennep of Cultivate in Dublin, "is just a buzzword for sensible gardening." In the courtyard behind the building in Temple Bar - where at first sight the containers appear to hold just a collection of interesting plants gathered together by an enthusiast - several permaculture principles are at work. Most easily explained is that of layering or stacking, an idea borrowed from the forest. Plants of varying heights are grown in close proximity, which means a compact space can generate a large amount of produce (ideal for urban gardeners with only a balcony or small yard). In one substantial timber box, for instance, a tall pear tree, a middling loquat and a shorter blackcurrant all happily coexist.
Stacking may combine plants that benefit each other in different ways. "You're stacking so that one plant that needs less sun is shaded by another," explains van Lennep, "and you're stacking to enable one plant to climb onto another. And you're stacking so that one can repel the pests for another." Pelargonium (tender geranium), he points out, is used here to keep whitefly away from the edible Cape gooseberry. Nearby, an Acacia maidenii, a medicinal plant, contributes to the group by producing nitrogen at its roots (as do other members of the pea family, Fabaceae); this is then used by the neighbouring plants. A tree tobacco (Nicotiana glauca) helps out by bearing small flowers that appeal to predatory insects, which, in turn, control pests.
Plants that work well as a team are known as "guilds". One of the most famous guilds is the native American "three sisters": maize, pole beans and squash. The maize acts as a climbing frame for the beans, the beans supply nitrogen to their companions, and the huge leaves of the squash are a living mulch at the feet of the other two, conserving moisture in the soil and preventing weeds from germinating.
Stacking to form mutually beneficial communities is just one of the ways that permaculturists look to nature for inspiration. Nature is expert at preventing waste and conserving energy: permaculture gardeners compost all their detritus (yes, some even have composting toilets) and recycle it in the soil, where it nourishes another batch of crops. And in permaculture, a system of "zones" helps to loosely delineate the growing operation by the amount of human attention needed in each one. High-maintenance crops are nearest the house in zone one; progressively farther away are, for example, the vegetable and composting area; perennial crops and an orchard; timber for coppicing; and, finally, a "wilderness". It's all common sense, of course, but of the kind that some gardeners seem to lack, as they tuck the kitchen garden as far as possible from the house.
One of the most appealing facets of permaculture is the creation and harnessing of highly productive relationships on the "edge", where two kinds of habitats meet, the woodland edge being the most common. My favourite "edge" is the "chicken greenhouse", where a glasshouse is built on to the sunny side of a hen house, and an interconnecting vent is left open at the top of the party wall. The heat from the birds keeps the greenhouse warm on cool nights, and the greenhouse warms the hen house during the day. The carbon dioxide emitted by the chickens fosters plant growth, as does their manure. Every bit of energy is harnessed at least once. Conjoining these two seemingly disparate units creates a new, multipurpose and cohesive entity.
Few gardeners have both chickens and greenhouses, so it's not feasible for them to go all the way to this particular edge. But there is much else that permaculture offers. At the very least, it coaxes us to open our eyes to intriguing and wonderfully logical possibilities. jpowers@irish-times.ie
• Cultivate is on Essex Street West, Temple Bar, Dublin 2; 01-6745773; www.cultivate.ie. For a beginner's guide to permaculture, see www.spiralseed. co.uk/permaculture. The Organic Centre, in Co Leitrim, is running a permaculture weekend on July 7th and 8th. Details and booking from 071-9854338 or www.theorganiccentre.ie. You can also sign up for an intensive 10-day permaculture course in west Cork from August 10th to 19th; www.westcorkpermaculture.org