There is nothing quite so dispiriting as marching down to the plot on a damp May morning, full of hope, only to find your carefully raised courgettes reduced to a row of bare stalks. Slugs and snails are the single biggest complaint among British allotment holders and kitchen gardeners, and it is easy to see why. A single night's feeding can wipe out a whole sowing of lettuce, and the damage always seems to land on the plants you were most looking forward to. The good news is that you do not need to scatter blue pellets about the place to win the battle. With a bit of patience, some clever barrier work and a willingness to go out after dark with a torch, you can protect your seedlings naturally and keep the garden a safe place for children, pets and the frogs and birds that will do much of the work for you.

Know What You Are Dealing With

Not every slug is a villain. The large black slug and its brown cousins are mostly interested in rotting vegetation, and they do a useful job breaking down compost. The real culprits are the smaller species — the grey field slug, the keeled slug that spends much of its life underground, and the netted slug that lurks among your salad leaves. All of them are at their most active after rain, in mild damp weather, and between dusk and dawn.

That last point matters. If you understand when they feed, you can plan your defences around their habits rather than fighting them blindly. They also prefer soft, tender growth, which is exactly why seedlings and young transplants suffer so badly while established plants usually shrug the damage off.

Encourage Predators Into the Plot

The most effective long-term slug control is a healthy population of things that eat them. A garden that is alive with wildlife will always have fewer slugs than a bare, tidy one.

• Frogs and toads are voracious slug eaters. A small pond, even a sunken washing-up bowl with a few stones for access, will bring them in. Toads in particular will stay in a damp corner for years.
• Birds — especially thrushes, blackbirds and robins — will pick slugs off the soil surface, particularly in early morning. Encourage them with a hedgerow, a berry-bearing shrub and a bird bath.
• Hedgehogs need a gap in the fence and a wild, undisturbed corner with a pile of logs or leaves to nest in. Never use slug pellets if you want hedgehogs; they are poisoned by them.
• Ground beetles and centipedes patrol the soil at night. Leave some areas mulched and undisturbed so they have somewhere to shelter.
• Slow worms love a compost heap or a sheet of black plastic laid on the ground. If you have them, you have a slug-eating machine.

Copper Barriers and Physical Defences

Copper really does work. Slugs receive a mild electric shock when their slime-covered bodies touch it, and they will turn back rather than cross it. For raised beds, copper tape stuck around the top edge of the timber is a sound investment, though you must check it regularly for leaves and soil bridging the gap. For individual plants, copper rings pushed into the soil around a young courgette or hosta are excellent.

Other barriers are worth trying, though results vary with the weather:

• Sharp grit or crushed eggshell around the base of plants. Cheap, but rain and soil splash quickly reduce its effectiveness, so top it up.
• Wool pellets — these swell when wet to form a rough, irritating mat, and they add nitrogen to the soil as they break down.
• Barrier collars cut from plastic bottles, pushed a couple of centimetres into the soil, will protect a single transplant while it establishes.
• Nematodes watered onto damp, warm soil in spring or early autumn can reduce soil-dwelling slugs substantially, though they need to be applied at the right temperature to work.

Night Patrols and Traps

An hour after dark, ideally after rain, take a torch and a bucket down to the plot. You will be astonished how many slugs you find on the surface. Drop them into soapy water or a bucket of salty water, or simply relocate them to a wild corner well away from your beds. Two or three patrols a week through late spring can break the back of a local population.

Traps work alongside this. A sunken jar filled with beer will lure and drown slugs, and half a grapefruit or an upturned flowerpot filled with damp newspaper makes a perfect daytime hiding place — turn it over each morning and collect what is inside. Remember to water your beds in the morning rather than the evening, so the surface dries off before the nightly feeding shift begins.

Grow Plants That Can Take It

Finally, adjust your methods. Raising seedlings in modules and planting them out when they are sturdy gives them a far better chance than sowing straight into slug territory. Sow a little more than you need, so a few losses do not matter. Keep the plot tidy of damp hiding places near your beds, and accept that a certain amount of nibbling is simply part of growing food outdoors. A garden with frogs in the pond, blackbirds on the lawn and a torch in your hand at dusk is a garden that is working with nature rather than against it — and the seedlings will thank you for it.