Why coastal gardens face a different pest battle

Gardening by the sea is a joy, but the pests have read the menu too. Salt-laden wind, free-draining sandy soil and constant air movement create a pest profile quite unlike an inland plot. Leatherjackets and other clay-soil nuisances rarely trouble you, while slugs thrive in the damp strip behind a dune bank and aphids simply parachute in on the breeze. In hot, still pockets — a sheltered south-facing patio behind a wall, say — humidity stays low and red spider mite can build up alarmingly fast. Wind also strips away shelter, so birds, beetles and other predators have fewer places to live, and pest numbers creep up unchecked. Understanding that balance is the first step: most of the work here is about creating shelter and encouraging the creatures that eat the problem for you.

Slugs and snails: barriers that actually work

Coastal slugs are persistent, and sandy soil drains so fast that the damp, dark conditions they love are patchy. They concentrate instead where you water most: raised beds, pots and the shaded side of a hedge.

• Water in the morning, not the evening, so the surface dries before the night patrol begins.
• Copper tape or rings around pots and raised beds, kept clear of leaves that could bridge the gap.
• Sharp grit or crushed shell as a collar around prized plants; shell grit is often cheap and local near the coast.
• Sheep wool pellets hold moisture in sandy ground while irritating the slug's foot.
• Nematodes watered on in warm, damp spells work well, but keep the ground moist for a fortnight afterwards.
• A torchlit night patrol after rain is still the most reliable method in a small garden.

Encourage the predators that work for free: thrushes, hedgehogs, slow worms, ground beetles and toads. A log pile, a shallow saucer of water and a rough, unmown edge all help. Avoid metaldehyde slug pellets, which harm pets, hedgehogs and birds; ferric phosphate alternatives are far kinder.

Aphids and the wind-borne arrivals

Aphids, thrips, whitefly and cabbage white butterflies all arrive on the wind, so a coastal plot is never really free of them. Watch the lee side of walls and hedges first — that is where flying insects settle after a blow. Ants farm aphids for their honeydew, so a trail of ants up a stem is a clue to look closer, and the sticky residue soon turns into sooty mould on the leaves above.

Build a standing army of predators instead. Ladybirds, hoverflies and lacewings breed happily where there is nectar and pollen, so leave a few fennel, dill, coriander and yarrow plants to flower, and tuck in calendula, marigolds and poached egg plant. A strong jet of water knocks aphids off tender growth, and soft soap spray on a cool evening deals with the rest. Don't overfeed with nitrogen — soft, sappy growth is an open invitation.

Trouble in pots and dry corners

Containers are the coastal gardener's friend, but vine weevil grubs love them. If a plant in a pot suddenly collapses despite looking well watered, tip it out and check the roots for fat, white, C-shaped grubs. Biological controls applied in late summer and early autumn are the tidiest answer on warm, free-draining soil. In hot, airless corners, fine webbing and pale speckling on leaves means red spider mite; raise the humidity by damping down paths and grouping pots together rather than reaching for a spray.

The post-storm inspection routine

Once a gale has passed and the salt has settled, spend twenty minutes walking the garden. Fresh damage is where pests get a foothold.

• Inspect the lee side of walls, hedges and sheds first — that is where wind-borne insects land.
• Turn over the newest leaves and growing tips, where aphids and whitefly hide.
• Check torn or bruised foliage; wounds invite trouble and slugs shelter in the folds.
• Clear fallen leaves and debris from around pots to remove daytime hiding places.
• Re-firm netting and fleece the wind has loosened — a gap is all a cabbage white needs.
• Remember that brown, scorched leaf edges are usually salt burn, not pests. Don't spray; rinse the foliage with fresh water if rain doesn't follow.

Shelter, predators and a little healthy untidiness

The single best pest control on an exposed plot is a good windbreak. A mixed hedge of griselinia, escallonia, tamarisk, sea buckthorn or olearia cuts wind speed, reduces salt damage and gives birds somewhere to nest and hunt from. Allow a little untidiness: seedheads left over winter, a stone pile for slow worms, leaf litter for beetles. Mulch with homemade compost to hold moisture in sandy soil, water thoroughly in dry spells so plants aren't stressed, and skip the broad-spectrum sprays that kill your allies along with the pests. Do that, and the balance tips steadily in your favour.