A Sting Worth Taking

Every British gardener has a nettle story, and most of them involve a bare ankle and a few choice words. Yet the same plant that makes us hop about in the undergrowth is one of the most useful things growing in our hedgerows, woodlands and neglected corners. Young nettle tops arrive just as the hungry gap sets in, before the first broad beans and long before the tomatoes, and they are packed with iron, calcium, vitamin C and protein. Better still, they can be turned into a soup that tastes far more sophisticated than its humble origins suggest, and whatever you don't eat can be steeped into a free, nitrogen-rich plant feed.

For anyone gardening with wildlife in mind, nettles are also an asset rather than a nuisance. A patch left to itself supports a remarkable range of insects, and picking a modest harvest from the edges does no harm at all.

When and Where to Pick

Timing matters more than anything else with nettles. Pick from early March through to late May, while the plants are young and the leaves are still a deep, tender green. Once nettles come into flower, usually from June onwards, they develop tiny gritty crystals called cystoliths that can irritate the kidneys, and the flavour turns coarse and bitter. As a rule, take the top four to six inches of growth, pinching or snipping just above a pair of leaves so the plant bushes out rather than dying back.

• Wear stout gloves — washing-up gloves are ideal — and use scissors rather than bare hands.
• Choose clean ground away from busy roads, sprayed verges, railway lines and anywhere dogs are walked.
• Never uproot a plant; cutting the tops encourages fresh growth and keeps the patch productive.
• Pick on a dry morning after dew has lifted, and use your harvest the same day if you can.
• Take from several plants rather than stripping one, and never clear a whole stand.

A Bowl of Nettle Soup

Cooking destroys the sting completely, so there is nothing to fear once the leaves hit the pan. You will need roughly 200g of young nettle tops, a good knob of butter, one onion, one medium potato, a litre of vegetable or chicken stock, a grating of nutmeg, and a swirl of cream or a spoonful of crème fraîche to finish. Rinse the nettles in a colander, wearing gloves until they are in the water.

Soften the chopped onion in the butter over a low heat, then add the potato, peeled and diced, and the stock. Simmer for ten minutes until the potato is tender, then tip in the nettles and cook for just three or four minutes — any longer and you lose that bright green colour. Blend until smooth, season generously, and add nutmeg to taste. The result is earthy and slightly iron-rich, somewhere between spinach soup and watercress, and it freezes beautifully in portions.

Free Plant Food from the Same Patch

Nettles are unusually high in nitrogen, which makes them the classic ingredient for a homemade liquid feed. Fill a bucket or lidded container with roughly 1kg of fresh nettle tops, or about 200g dried, and cover with 10 litres of water. Weigh the leaves down with a brick, put the lid on, and leave it somewhere out of the way for one to two weeks. Stir it every couple of days. It will smell powerfully of ammonia, so keep it well away from the kitchen door.

When the liquid is dark and the leaves have collapsed, strain it off and dilute one part feed to ten parts water before use. Apply every fortnight to leafy crops, courgettes, tomatoes and hungry flowering plants. Undiluted, it is strong enough to scorch roots, so resist the temptation to use it neat. The spent leaves can go straight on the compost heap, where they will help heat the pile.

Leaving Some for the Butterflies

Here is the part that matters most for British wildlife. Nettles are the larval food plant for some of our best-loved butterflies — the peacock, small tortoiseshell, comma and red admiral all lay their eggs on them, and the caterpillars will eat nothing else. A stand of nettles also hosts aphids in spring, which in turn feed ladybirds, hoverflies and hungry blue tit chicks.

The trick is to manage rather than remove. Keep a dedicated patch, perhaps along a fence or at the back of a border, and cut it in rotation — a third in late May, a third in July, the rest left alone — so there is always fresh young growth for a new generation of caterpillars. If you must clear nettles from a path or vegetable bed, do it before the eggs hatch in spring, or leave it until autumn when the butterflies have finished. Come September, let a few plants set seed and the goldfinches will thank you.

A Few Practical Notes

Only ever pick nettles you can identify with absolute certainty, and avoid any plant you cannot trace to clean ground. If you are new to foraging, start with a small patch in your own garden, where you know exactly what has been sprayed and who has walked. Wear gloves right up until the leaves are in the pan, and wash your hands afterwards regardless.

Finally, remember that a nettle patch is a garden in its own right. Treated with a little restraint, it will feed you in March, your tomatoes in June, and a cloud of butterflies all summer long — which is a generous return for a plant most of us spend the year trying to avoid.