The call of the ramsons

There is a particular moment in mid-April when you walk into a damp wood and catch a smell before you see a single leaf: green, sharp, faintly sweet, and unmistakably garlic. That is wild garlic, also called ramsons, growing in dense carpets under beech and oak, along stream banks and in the deep shade of old hedge banks. It arrives early, often before the bluebells, and it is one of the most generous free crops the British countryside offers.

The leaves are at their best for a few short weeks, roughly late March to early May depending on where you live, with everything running later in the north and on high ground. Once the starry white flowers open in May, the leaves toughen and the flavour turns harsh and lingering. So pick young, tender leaves while they are still glossy and soft, and turn them into pesto while the season is on your side.

Identifying wild garlic with confidence

The first rule of foraging is simple: never pick anything you cannot identify with complete certainty. Wild garlic leaves are broad, soft and bright green, lance-shaped, growing in loose clumps straight from the ground, often with a slight droop at the tip. The test that settles it is the sniff test. Crush a leaf between your fingers and the garlic smell is immediate and unmistakable. If there is no smell, it is not wild garlic.

There are lookalikes worth knowing. Lily of the valley has similar leaves but they are glossier, usually paired on a single stem, and they smell of nothing much. Lords-and-ladies has arrow-shaped leaves blotched with purple-black. Young leaves of some garden bulbs can cause confusion too. None of these smell of garlic, which is why the crush-and-sniff habit matters.

Pick away from dog-walking routes at nose height, avoid roadside verges and anywhere that might have been sprayed. Take a basket or a cloth bag rather than a plastic one, which makes leaves sweat and bruise. Wash everything well in cold water, then dry it thoroughly in a salad spinner or on a clean tea towel. Wet leaves make watery pesto.

Picking lightly: law, etiquette and hedgerow wildlife

Picking leaves for personal use is generally allowed where you have lawful access, but uprooting any wild plant without the landowner's permission is an offence under the Wildlife and Countryside Act, and commercial picking needs consent. Never pick in a Site of Special Scientific Interest or a nature reserve without permission, and always ask on private land. Good foraging leaves the place better than it found it.

• Take one leaf in three or four from each clump, never strip a patch bare.
• Leave the flowers alone. They feed early bees, hoverflies and bee-flies at a time when little else is in bloom, and seeding keeps the colony alive for next spring.
• Stay on paths where bluebells grow alongside. Trampled bluebell leaves weaken the bulb, and the plants take years to recover.
• Don't dig up bulbs. If you want wild garlic at home, buy it from a nursery, in the green or as dry bulbs.

The pesto

This makes about two small jars, and every quantity is forgiving. Adjust as you taste.

• 100g young wild garlic leaves, washed and thoroughly dried
• 50g hazelnuts, lightly toasted and cooled, or walnuts or pine nuts
• 50g hard cheese, finely grated — a well-aged British hard cheese works beautifully, as does a Parmesan-style one
• 150–200ml cold-pressed rapeseed oil
• Finely grated zest of half a lemon, a pinch of sea salt and a good grind of black pepper

Pulse the nuts in a food processor until they look like coarse crumbs. Add the leaves a handful at a time, then the cheese, zest, salt and pepper. With the motor running, pour the oil in a steady stream until the mixture just comes together. Stop there: you want a loose, spoonable paste, not a smooth purée, and over-blending turns the colour dull. Taste and adjust. If it is too fierce, add more cheese or a small handful of flat-leaf parsley. If it is too thick, add oil. A little extra lemon lifts the whole thing.

Growing your own supply in a shady corner

Wild garlic is one of the easiest wild plants to bring into a garden, and it earns its keep as ground cover under fruit trees, in a damp corner or along a north-facing border. It wants shade, moisture and leafmould-rich soil. Plant bulbs in autumn, or buy plants in the green in spring and settle them in while they are still leafy. Growing from seed is slow and uneven, so plants are the practical route.

It spreads by seed and by offsets, so give it a mown edge or plant it in a sunken bottomless bucket to keep it in bounds. The leaves die back by early summer, so pair it with ferns, hellebores and hardy geraniums to fill the gap. This is also why the picking season is short: the plant is storing energy for next year, not making leaves for you.

Freezing, storing and using it up

Kept in a sterilised jar under a film of oil, the pesto will last a fortnight in the fridge. For longer, spoon it into an ice cube tray, freeze, then tip the cubes into a bag, where they will keep for three to four months. Use them straight from frozen, dropped into hot pasta, swirled through a soup or stirred into a risotto at the end of cooking.

Beyond pasta, it is excellent on new potatoes, spooned over roast vegetables, folded through spring greens, whisked into a salad dressing or spread under the skin of a roast chicken. Beat a little into soft butter with lemon zest, roll it into a log and freeze it for the grill. Pick a bagful in April, blend it, freeze it in cubes, and by the time the dark evenings arrive you will have a bright spoonful of spring waiting in the freezer.