Wednesday, 24 February 2010

How Sustainable is Your Garden?

The UK government recently launched a new approach to food production over the next 20 years (The Food Strategy), including the aim of greater sustainability in our food supply. In the Guardian report of (Environment Secretary) Hilary Benn’s speech to the Oxford Farming Conference he is quoted as saying:

"Food security is as important to this country's future wellbeing, and the world's, as energy security. We need to produce more food. We need to do it sustainably. And we need to make sure what we eat safeguards our health ...We know that the consequences of the way we produce and consume our food are unsustainable to our planet and to ourselves ...We know we are at one of those moments in our history where the future of our economy, our environment, and our society will be shaped by the choices we make now." He said consumers, rather than retailers, should lead by buying "greener" food, wasting less and growing more of their own.

Interestingly, the imperial war museum is staging an exhibition this year about how we Brits coped with food shortages during WW2, including grow-your-own, eating seasonal produce and recycling. Perhaps with the current revived interest in these areas, we can learn from the experience of our grandparents?

Sustainability is also prominent in this year's Gardener's World Live Show, with the announcement by NS&I (National Savings), the show sponsors, of the winning entries for their “Growing Gardens Today” competition.

So, growing your own food is a sustainable choice in your garden, and sustainability is “a good thing”, but ...

What exactly do we mean by sustainable?

A short while ago my local group of the Society of Garden Designers (Southampton Cluster Group - contact me for more information) were pleased to have Rosie Yeomans, a tutor in garden design & horticulture at Sparsholt College, and one of the presenters on Radio 4's "Gardeners' Question Time", lead our discussions on the subject. Rosie defined it very succinctly ascreating and managing a garden with as little input as possible”.

Aspects of sustainability from our discussions can be summarised as:

If you’re a gardener:

  • garden organically – reliance on input of fossil-fuel-derived fertilisers & pesticides is not sustainable; use natural barrier methods to protect crops, not poisons;
  • multiply your own plantstock from cuttings or seed – join a gardening club – swap with friends, family & neighbours;
  • use mixed-species hedging, and allow natural undergrowth to develop, rather than keeping it "clean";
  • conserve natural resources – compost your waste in a heap, rather than a plastic bin, of at least 1 cubic metre (they need air & water to work, and space to work around them) and use it to feed your soil; mulch to preserve moisture, suppress weeds & maintain soil structure;

Design decisions:

  • change as much lawn as possible into more productive green space – meadows, shrubs & trees will give much better habitat / environmental benefits and need far less input;
  • plant sensibly to fit the local climate & garden microclimate - avoid wasting resources on plants that don’t really belong – whether “native” or “exotic”;
  • manage your rainwater, don’t flush it down the drain! Food crops, especially, need a high water input, so consider the movement & storage of rainwater in your design; use whatever elements of the rainwater chain you can (green roofs, rain cups/rain chains, storm-water planters, permeable surfaced paths & patios, rain gardens, swales, ponds & bog areas. You can see more rain garden information on my website .

The HESCO garden at the 2009 RHS Chelsea show, includes a short video clip describing how rainwater is managed through the features of the garden

If you have a pond, be careful what you plant in it, and especially what you do with any excess plant growth (or even water from emptying it) to prevent alien species from escaping into the natural environment where they can become invasive & destroy native ecosystems - for more information see the "
Be Plant Wise" campaign endorsed by celebrity TV gardener Charlie Dimmock.

Materials choices:

  • reuse existing hard landscape materials, so far as possible (eg using old paving as a base for a utility area such as beneath a shed);
  • recycle materials where they can't be reused (eg breaking up old concrete or paving for use as part of the hardcore sub-base beneath new hard landscape);
  • use reclaimed materials for new features, if possible (eg old stock bricks for garden walls & paths);
  • use recyclable materials for new components (eg avoiding pressure-treated timber, which can't be chipped & composted at the end of its useful life);
  • use locally-sourced materials to minimise transport energy input;
  • use sustainably-managed resources (e.g. FSC-approved timber, alternatives to peat, etc);

The subject of sustainable materials used within a garden design is a tricky one.

Take, for example, decking - which is still an extremely useful & popular surface material in some contexts, despite the "yesterday's fashion" connotations. There are basically 3 "flavours" of decking:

  • cheapest is pressure-treated softwood, which is relatively low energy to produce, usually comes from European, FSC-certified, sources where the forests are managed sustainably and shipping the timber to us doesn't need huge transport energy. But pressure-treatment uses non-sustainable chemicals, which prevents the timber from being recycled at the end of its 20-year-or-so lifetime. It probably also needs regular chemical re-treatment to keep it sound and looking good.
  • hardwood, which is more expensive, but lasts longer - it doesn't need chemical treatment (except, maybe, for a plant-derived oil), is relatively low energy to produce (though the trees grow more slowly, so can't be replaced as quickly), but it mainly comes from tropical forests, so has high shipping energy and the forest management may not be FSC-assured. We certainly don't want to lose rain forests, but hardwood timber, without chemical treatments, has the advantage that it can be recycled at the end of its (much longer) lifetime.
  • composite, which is manufactured from waste hardwood and recycled plastic, into boards that have the look and feel of hardwood timber, but which don't require any treatment for an extended lifetime, and won't rot, warp, split or splinter. They require energy to manufacture, but can be low transport costs (made in the UK), and have sustainable credentials through their use of otherwise waste materials and their long, treatment-free lifetime. They may well be the most expensive initially, but perhaps comparable when lifetime costs are considered.

    Sustainable, or "green", building materials is an extremely complex area!

For more information click here

There are many more elements to sustainability and, not surprisingly, it’s strongly linked to many of the topics I’ve previously written about:

Further information on sustainability in gardens & landscaping can be found here

If you'd like help taking further sustainable steps in your garden, but aren't sure how to go about it, call in a professional - me!

If you enjoyed reading this article, and would like to subscribe to my regular updates, but aren't sure how to do it, click here

No comments:

Post a Comment