Salt, wind and sunshine: what a coastal plot offers

Gardening by the sea is often described as difficult, but the conditions that make roses sulk and lettuces bolt are exactly what a group of tough, delicious native plants have evolved to enjoy. Salt-laden wind, free-draining sand or shingle, ground that is often alkaline from crushed shell, and bright, unfiltered light — these are the ingredients that suit sea kale, sea beet and their kin down to the ground.

Better still, most of them are perennials. Plant them once, give them a sensible start, and they will crop for years while looking entirely at home among the thrift and the sea campion. This is edible gardening that works with the coast rather than against it.

Sea kale: the queen of the seaside bed

Sea kale (Crambe maritima) is the plant to start with. It forms a mound of thick, blue-grey, wavy leaves and sends up clouds of honey-scented white flowers in early summer. In the kitchen it earns its place twice over: the young spring shoots are blanched and eaten like asparagus, and the leaves can be cooked like cabbage once the plant is established.

It has a deep taproot, so plant it where it will stay. Sow seed in autumn or early spring in modules, or take root cuttings about 8–10cm long in late winter and lay them horizontally in gritty compost. Space plants 60–90cm apart in full sun with sharp drainage; add horticultural grit and a handful of lime if your soil is at all acid.

Resist harvesting for the first two years. From the third spring, cover a crown with a bucket or an upturned terracotta pot in late winter. Shoots will be ready to cut at 10–15cm in roughly three to four weeks. Take no more than a third of them and let the rest grow away, and you can keep picking for years.

Other coastal edibles worth a space

• Sea beet (Beta vulgaris subsp. maritima) is the wild ancestor of chard and beetroot, with glossy leaves that can be cut almost all year. It self-seeds gently and tolerates wind better than any spinach you can buy.
• Rock samphire (Crithmum maritimum) is slower and fussier, needing very free drainage — a raised bed or pot of grit-rich compost in full sun suits it. Pick the fleshy tips from June to August for pickling or blanching.
• Marsh samphire (Salicornia) is an annual that genuinely wants salty ground. Grow it in a container and water occasionally with diluted sea water, roughly one part sea to three parts fresh.
• Sea purslane (Atriplex portulacoides) makes a low silver-grey hedge and gives salty leaves for fish dishes from spring to autumn.
• Alexanders, scurvygrass and wild cabbage are all worth trying if you have room. Alexanders is a handsome early herb; wild cabbage makes a sturdy, long-lived clump for cut-and-come-again leaves.

Preparing ground and planting on an exposed site

Work garden compost into the top 15cm, plus grit on heavy soil. Seaweed is a fine autumn mulch, but rinse it first so you are not adding extra salt to already salty ground. Avoid rich, nitrogen-heavy feeding: soft, sappy growth is exactly what coastal gales shred.

Shelter matters more than soil. A permeable barrier — woven hazel fencing, a slatted screen or a low hedge such as sea buckthorn or elder — filters wind rather than blocking it. Solid fences simply create damaging turbulence on the leeward side. Position any barrier at roughly two to three times its height from the bed for the best effect.

On the most exposed plots, deep containers are a genuine option. Use a loam-based compost such as John Innes No 3 mixed with about a third horticultural grit, choose pots at least 45cm deep for taprooted plants, and plant in spring so roots settle before the winter gales arrive.

Looking after them through the year

• Water new plants well through their first summer, in the morning and at the base of the plant. Once established, most coastal natives manage on rainfall alone.
• Cut faded flower stems back in late summer to put energy into the roots rather than seed.
• Net young crowns against pigeons and rabbits, and watch seedlings for flea beetle. Cabbage white caterpillars will find sea kale — pick them off by hand.
• Lift and divide congested sea kale every four or five years in early spring, replanting the strongest offsets.

Harvesting and eating your coastal crop

Your season runs something like this: sea kale shoots in March and April, then leaves from May to September; rock samphire tips from June to August; sea beet and sea purslane almost continuously. Pick in the morning when the leaves are turgid, and always leave the growing crown intact.

In the kitchen, less is more. Steam sea kale shoots for four or five minutes and dress with butter and lemon. Blanch the leaves in two changes of water if you find them bitter, then treat them like spring greens. Rock samphire needs only a minute in boiling water before it goes into vinegar with a few peppercorns, or it can be chopped raw into a salad. Sea beet and sea purslane both shine alongside mackerel or simply wilted in a hot pan with garlic.

Do grow these plants rather than collecting them from the wild. Cliff-dwelling species rarely survive being dug up, and many coastal sites are fragile and protected. A packet of seed and a spare corner of the garden will give you a better crop, year after year, without harming the places these plants come from.