Gardening without poisons

Second issue June 2004

For a printable (PDF) version click here

All our hopes for sustainable development will come to nothing unless we all learn to 'tread more lightly on the planet'. Farmland covers almost three quarters of the land surface of Essex, so how farmers manage their land is very important. Private gardens cover a sizeable proportion of the rest and, with today's pressures on our countryside, serve as a vital refuge for wildlife, so how you manage your little bit of land can make a difference as well.

Whether or not you have the time to take on wildlife gardening full-scale, you can still help by cutting down on chemical sprays, which are as damaging in the garden as in the countryside. Less use of chemicals means more natural food for wildlife, less residues on the food crops you grow, less toxins to be cleaned out of the water supply.

Gardening successfully without chemicals is not just a matter of cutting them out. Just as farmers need to change many aspects of how they manage their land, so in a garden you will do best by adopting a combination of measures.Light touch gardening also means choosing the right plants and giving them a good chance; encouraging the natural predators of pest species; adopting new methods of control that do no 'collateral damage'.

1 Choose plants that look after themselves

Don't create a plant protection problem by trying to grow unsuitable plants. If they are growing in the right conditions most established plants - and especially natives - will shrug off all but the most severe pest attacks.

If you have persistent problems with particular plants, try moving them somewhere else. If you can't find anywhere suitable, give up the unequal struggle and grow something different - they are trying to tell you that they don't belong in your garden at all!

2 Give new plants a fighting chance

Beware sowing or planting seedlings too early, especially on a cold, heavy soil. When plants have to cope with soil or weather that is too cold for them, they struggle to get going and are a sitting target for pests. You can use cloches or fleece to warm the soil first and to protect plants in the critical first week or so. You can also sow indoors in pots or a container and plant out when the seedlings are big enough to survive a few nibbles. Remember to keep back a few spares to replace the plants you do lose - it usually involves no more cost and little extra effort.

3 Prevention is better than cure

Many pests on vegetable crops can be excluded by crop protection nets and fleeces, available from some garden centres. A cheaper alternative: lemonade bottles or yogurt pots with their bottoms cut off placed over young plants and pushed into the soil.

To protect against cabbage root fly, make collars 15cm or so across and cut them to fit tightly round the stem when planting: these prevent the adult root fly from crawling down into the soil to lay its eggs. Old carpet underlay is ideal.

4 Nip problems in the bud

Get used to looking at your plants closely and often. If you have not done it before, it will open up a new world of tiny creatures engaged in a continual battle for survival. It will also enable you to detect the most destructive pests in the early stages, when a few quick squeezes between finger and thumb may snuff out the problem. You will also be able to see whether or not nature's own defence troops are getting on top, before you bring in the big guns.

5 Recruit nature's own defenders

The two most important helpers in the battle against slugs are hedgehogs and frogs. So if you do not yet have a garden pond, try to install one as soon as possible. It does not need to be very big - see our guidance on ponds.

Hedgehogs appear to be in decline at the moment, so they need your help. A little cat food put out on autumn evenings or a snug winter home might be enough to persuade them to set up home. Click here for more details.

6 ... and make them feel at home

Many insect predators need somewhere to hide from their enemies during the day, ready to come out to do some good work on the night shift. Give them a few strategically placed piles of stones or logs to hole up under.

You also want your insect friends (see below) to lay their eggs in your garden, so that there are plenty of their young about to get to grips with pests early in the season. Stinging nettles are ideal in this respect because they attract beneficial insects to lay their eggs but the pests they harbour do not pose a threat to other plants. Let a clump grow in a sunny, out-of-the-way corner of the garden, and cut them down in summer so that the hungry predators move out into the garden.

7 Keep chemical warfare as a last resort

Before reaching for the sprayer, remember that the aim is not to prevent all pest damage but to reduce it to acceptable levels.

Organic sprays break down quickly in the environment and that makes them safer, but the important thing about insecticides is not whether they are organic but how selective they are. Biological controls with no side-effects are now available for garden use (see table below). The active agent in Bactospeine, for example, is a bacterium called Bacillus thuringiensis that attacks caterpillars alone.

8 Recycle, recycle, recycle

A healthy soil means healthy plants that are better able to resist attack by pests or diseases, and the best way to create a healthy soil is to recycle waste organic material, preferably composted.

If you don't have a compost heap nature will still do the recycling for you. Mulch roses and shrubs with grass cuttings or, in dry weather, leave them on the grass and save watering. Rather than barrowing leaves or hedge clippings away, stack them in the shade under shrubs or trees. In winter, dig a trench to bury organic kitchen waste and grow runner beans or courgettes on top the following summer.

9 Stick with it

You may find light-touch gardening difficult or frustrating at first, but don't be put off if you lose the early skirmishes. Your garden may have few natural predators now but, as soon as you stop using chemical weapons, a better balance of predator and prey species starts to develop so that pest damage gradually becomes less and less of a problem.

Know your friends

Drawing by Richard Allen

Ground dwellers

Ground and rove beetles

• important slug predators;
• also eat root fly eggs and larvae.

Centipedes

• 15-83 segments, 1 pair legs/segment;
• nocturnal hunters, eating slugs, snails, etc.
• need daytime refuges

Don't confuse with millipedes

• 2 leg pairs/segment;
• feed on plant matter.

Flying corps

Anthocorid bugs

• 3-5 mm, reddish-brown to dark brown;
• eat mainly greenfly, also other pests;
• need trees and hedgerows for shelter and food.

Hoverflies

• 100 species in Britain, active summer/autumn;
• many mimic bees or wasps for self-protection but they have no sting and a less well-defined 'waist';
• larvae do the good work, eating 100s of greenfly mainly at night.

Lacewings

• three types: green, brown and powdery;
• larvae eat greenfly, also scale insects, caterpillars, mites;
• adults feed on nectar.

Ladybirds

• larvae eat mainly greenfly, active May-July;
• adults overwinter in undergrowth, cracks, etc.

Parasitic wasps

• young live on young stages of other insects;
• larger adults prey on caterpillars, smaller on aphids, scale insects.