The ultimate green gardening guide

As environmental awareness goes, it would be reasonable to think that gardeners are well placed to make a positive contribution to local and global welfare. Many don't have to be persuaded to carry out the basics - recycling, creating habitats for wildlife, or planting trees - because it's in their blood. But the focus of awareness has widened recently to take into account such things as the materials we use to build and plant, the water we use to irrigate and the energy consumed for machinery, heating and transportation.

Far from wanting to be put off one of the great pleasures in life, gardeners are now facing up to the fact that even the simple act of maintaining our gardens can have environmental implications. The bottom line for most people when making a garden is convenience and how much it is going to cost.

Fortunately, while it might make sense to let everything grow wild and keep a machete handy to hack a path to the front door once in a while, there are a number of areas where we can make an individual contribution to the stewardship of our immediate environment and the wider health of the planet.

Materials

Stone

With York stone retailing at £80 per square metre it's hardly surprising that many gardeners opt for cheaper Indian sandstone that can be bought for a quarter of the price. Reports of child labour and atrocious working conditions at some quarries have fuelled a debate on whether such imports should be regulated.

Marshall's, who are sponsoring the Chelsea Flower Show this year, have made it their mission to make sure their imported stone is sourced from quarries that have been inspected and approved. Other responsible suppliers will have visited quarries in India, China and Brazil to see for themselves how the product they want to import is being produced and the conditions that exist. While it may be sometime before a reliable certification can be put into place, ask your supplier how the stone is sourced, to help inform your choice.

Before you decide to build a new terrace, look to see whether existing materials can be re-used rather than simply condemning everything to f landfill. Old concrete slabs may not be everybody's first choice but, with a little imagination, can occasionally be used with, say, bricks to good effect. Even if you absolutely don't see them working in your garden there may well be someone who would be grateful for some free materials (schools, allotments, etc) so it's worth asking around.

www.marshalls.co.uk; www.rockunique.com; www.ced.ltd.uk

Timber

I don't know a gardener who owns a sun-lounger, let alone one that has time to stretch out on one. All the same, hardwood garden furniture, parasols and so forth are big business. Some, especially those that are suspiciously cheap, may well have been imported illegally at the expense of threatened forests, which has serious knock-on effects for native peoples and endangered flora and fauna. Eighty per cent of timber in Indonesia is being exported illegally and some of that finds its way to Britain. Under pressure from environmental groups such as Greenpeace, some retailers have pledged to "suspend" importing such timber immediately while others want to phase it out over the next 15 years - which is a polite way of saying that "we're not really that bothered".

Whether you are about to buy furniture, decking or new railway sleepers, all timber should come with a Forest Stewardship Council (FSC) certificate, proving that it is sourced from properly managed forests. This makes it absolutely clear and simple: if it doesn't have a certificate, don't buy it.

Reclaimed timber can be difficult to source and often needs extra work in preparing and preserving, but occasionally lumber from marinas and river landing stages makes ideal decking and adds a more rustic touch to a garden. Railway sleepers are perhaps even more passé than decking but they are still a realistic option for gardeners.

The popularity of imported charcoal for barbecues is destroying rainforests and having a detrimental effect on British woodland which, if properly managed, could supply several times the 60,000 tons of charcoal imported each year. Try to buy charcoal from a sustainable source in the UK that will help restore woodland and coppice management in this country. It may be more expensive, but that is the price tag for conscience-free gardening.

www.greenpeace.org.uk/Products/GFG/retailers.cf

www.fsc.org

Concrete

While the amount of cement used in gardens is a fraction of that used in the building industry, it is still hard to ignore the fact that cement production accounts for five to 10 per cent of all carbon-dioxide emissions. We are as addicted to it as we are to oil.

One alternative to concrete blocks and mortar is earth-rammed walls where excavations of sub-soil can be used to build free-standing or covered structures. Depending on how much clay (which helps bind the material) is in the soil, cement use can be reduced to a minimum or even avoided completely. This has become a particularly attractive material for anyone building a swimming pool as it saves both on raw materials and the cost of disposing of soil at a landfill site.

'Rammed Earth: Design and Construction Guidelines' by Peter Walker and BRE; www.worldchanging.org

Peat

Sterile, cheap, light and easy to extract, peat is still being used throughout the country despite being a non-renewable resource. Valuable habitats are being destroyed to satisfy the horticultural trade.

Large scale wholesale plant "factories", some of which actually own their own peat bogs, completely dominate the market for peat-based compost. Smaller nurseries, the pride of British gardening, are thus forced to use peat-based or peat-reduced compost for their very survival.

The increase in the use of peat alternatives (bark, coir, cocoa shell and spent mushroom compost) is, therefore, largely driven by demand from the amateur gardener and private and local authority landscapers. Commercial growers are less inclined to use peat alternatives for fear of quality control and simple economics. This, then, is a difficult nut to crack, for while concerns over plant quality can be resolved in time, gardeners must be prepared to pay more for plants grown in peat alternatives.

www.foe.co.uk; www.soilassociation.org

Water

The recent rain may well have eased pressure on aquifers but last year's drought galvanised many people to consider measures to deal with future water shortages. Installing an irrigation system is perhaps the most efficient way of watering your garden, directing water exactly where and when you need it. They are also invaluable for when you go on holiday and have no one to rely on to maintain the garden for you.

Collecting rainwater is becoming more and more popular and irrigation companies can install underground tanks that store much more than the space-hungry and somewhat ugly rain-water butts.

If your soil is free draining, use plants that have a measure of drought tolerance rather than being a slave to the hose. Herbs, prairie and silver-leaved plants are some of the more obvious drought-tolerant plants and these will need much less care than broad leaved plants such as hostas, gunneras and exotic plant species. Ground-cover plants, while in theory taking moisture from the ground, will provide leaf cover that will actually help prevent evaporation. Bare soil mulched with well- rotted compost or wood chippings will also prevent water loss.

Many of our front gardens have been paved over for car parking but this is to the detriment of green space and not only stops rainwater finding its way into the ground aquifers, but puts pressure on the drainage system, often resulting in sewerage discharge poisoning rivers.

www.waterwell.com

Site clearance

Did you know that you can be fined £5,000 for killing a great crested newt? That's per newt, by the way. Clearing a garden can disturb habitats for newts and other protected species, such as bats and dormice, so protection and/or re-location must be considered as part of the overall strategy. Where such animals exist it's worth getting in touch with your local council or ecology group for advice. Otherwise the budget for your garden could be squashed under one misplaced boot.

www.thompsonecology.com

Peak oil

The term "peak oil" refers to the point when global oil reserves begin to decline. As production falls (widely predicted as being within the next decade), prices will rise f sharply. While this will have obvious effects on the use of garden machinery, heated greenhouses and the cost of plants, perhaps the greatest impact will be on food production and its transport. Grow Your Own will, therefore, be taken to a higher level. Allotments, which have become fashionable again (as both a rebellion against intensive agriculture using pesticides and artificial fertisilers, and the simple realisation that fresh air, exercise and organic food is cheap and good for you), will come into their own. Many plots have been lost since the Second World War, so diminishing oil reserves may yet lead to an increase in the value placed on such land to produce locally grown food.

Without being too pessimistic, Grow Your Own may, one day, become much more than just a hobby. If an allotment is impractical for you, or the waiting list suggests it is unlikely you'll ever get one, try growing vegetables at home. You might even have a neighbour who can't, for some reason, manage their garden and might be willing to let you use it to grow food in return for a share of the produce. Local co-operatives may well become a way of life in the future so why not start now?

Recycle

Compost

Waste from your kitchen and garden will break down wherever it ends up, but rather than having to transport it to landfill sites that need careful monitoring to allow methane to escape, it's just common sense to have a compost heap at home or make sure your waste is recycled by either the council or a friend.

Any organic matter can be used, but a mixture of kitchen and garden waste (including shredded paper, card, cotton, pet hair, etc) is ideal. Grass clippings are perfect but should be added in layers between other waste to stop it from becoming too slimy.

Cooked food should not be added as it can attract rats. Neither should pernicious weeds such as bindweed, ground elder, couch or the dreaded Japanese knotweed.

The larger the garden the more room you will have for a decent-sized heap, which will be generally more efficient. Smaller ones can be made out of timber, bricks or blocks, and bins can often be supplied by your local council at a subsidised cost.

www.recyclenow.com/home_composting

Green Manures

A movement known as vegan organics is encouraging gardeners to use green manures to feed their soil without having to import animal fertilisers. Green manuring imitates the natural way of replenishing the soil by using a mixture of nitrogen-fixing plants, such as clover, and cereal crops, such as rye, to prevent nutrients leaching away during winter.

The principle of vegan organics concentrates on improving biodiversity, through the use of perennial and native plants, actively encouraging a wide range of insects and other invertebrates. Environmental impact is kept to a minimum through buying and selling locally, thereby reducing dependence on machinery and transport.

www.veganorganic.net

Chemicals

With fewer and fewer chemicals available to the amateur gardener, many have been forced to consider alternatives to pesticides and herbicides. Fortunately, there are a number of safe biological controls available, from nematodes to ladybirds.

www.greengardener.co.uk

Biodiversity

Ken Thompson's book No Nettles Required is an entertaining read reassuring us that we actually don't have to do that much to attract wildlife to our gardens. Avoiding pesticides will allow insects and invertebrates to thrive in even the most miserable looking garden and these, in turn (being at the bottom of the food chain) are your best bet for attracting the larger predators - amphibians, reptiles, birds and mammals.

Ponds also create perfect habitats for wildlife and even a washing-up bowl sunk into the ground in a sheltered position is better than no water at all. If there is room for a bigger pond, so much the better. Native plants are obviously useful for attracting wildlife but non-natives, with nectar, seeds and berries, can also have a positive effect on biodiversity. Bird-feeders are always popular but consider planting trees and hedging to create habitat for birds in your area.

Plants and structures

Trees

Trees not only provide habitats for a wide range of invertebrates, birds and mammals. They can, with careful planning, also be used to save energy in the home. Evergreen trees to the north and west will protect the house from cold winds while deciduous trees to the south and east will give shade in summer but allow sun to warm the house in winter.

Green roofs

Sheds, outbuildings and houses can increase their environmental credentials with a green roof. Roofs of stonecrop, sedum acre (which can be bought in rolls like turf) can be planted on just 50mm of soil and can survive for 28 days without water. More ambitious extensive systems with deeper planting beds can allow a much wider range of plants to be grown on what would otherwise be wasted space. Not only does this raise the footprint of the building in question (providing an environment for insects, birds and people to exploit) but it also helps to keep a building cool in summer, offsetting the effect of increased temperatures in urban areas and increasing the rate of carbon-dioxide/ oxygen exchange. It can also protect the roof itself, often doubling its life expectancy.

Lawns

Use a push mower where possible or - if you have space - let some parts of the lawn go wild and see what comes up. Two square metres of uncut grass produces enough oxygen to supply an adult with a year's supply. If you need to cut the grass, put clippings on the compost heap or leave clippings to feed the lawn with valuable nitrogen, phosphate and potassium. This will reduce the need for fertilisers. Grass clippings can also be used to mulch bare soil, suppressing weeds and reducing evaporation.

Peripherals

Garden lighting, while useful and effective in the garden, can be wasteful if not used correctly. The use of dimmer switches and directing light to reflect off a surface can reduce the amount of energy used. A lighting designer can advise accordingly. Patio heaters are ugly and are a blatant waste of energy. If you're cold, stay indoors or put more clothes on ... even better, do some gardening!

Anna Pavord, Cleve West and Carol Klein will be speaking at this year's 'Garden's Illustrated' lecture, 'Sustainability in Planting and Design' at the Royal Geographical Society, London SW7, on Tuesday 22 May, 6.45pm