Hedgerow fruit is the reward of a slow walk

There is a particular kind of autumn afternoon in the British countryside that asks nothing of you but time. A footpath, a lane, a high hedgerow with the last of the year's warmth in it, and the small quiet business of filling a basket. Blackberries and sloes are two of the finest free harvests in these islands, and neither needs a garden, an allotment or a subscription. They need a sharp eye, a pocket field guide, a little patience and the willingness to walk slowly.

Do it well and you come home with stained fingers, a couple of scratches and the raw material for crumbles, bramble jelly and enough sloe gin to see you through to spring. Do it carelessly and you risk picking something you shouldn't, or fruit you wouldn't want to eat. The difference is mostly preparation.

Getting your eye in: blackberries

Blackberries, the fruit of the bramble, are the easiest starting point. Look for scrambling, thorny stems arching over a hedge or fence line, with white or pinkish flowers earlier in the season and now clusters of fruit ripening from green to red to a deep, dull black. The berries are made up of many small juicy segments, and when you pick one the soft white core comes away with it, leaving your fingers purple.

• Colour: true black, often with a slight bloom. A berry that is still red or dark red is sour — leave it and come back in a week.
• Feel: ripe fruit comes away with the gentlest of tugs. If you have to pull, it isn't ready.
• Habitat: hedgerows, woodland edges, embankments and scrub, usually in sun.
• Watch out for: other dark hedgerow berries such as ivy and privet, which grow in tidy clusters and are not edible. If it isn't on a thorny bramble stem, be sure before you pick.

Fruit on south-facing sides ripens first. Take a mix of firm and soft berries if you're cooking with them, and eat a few straight from the hedge — it's part of the pleasure.

Sloes: the blackthorn's blue-black haul

Sloes arrive later, usually from late September into November, and they are the fruit of the blackthorn. The bushes are fiercely spined and often form dense, dark tangles in a hedge; in spring they carry clouds of white flowers before the leaves appear, which is how you learn to spot them for the rest of the year. The fruit is small, round and blue-black with a powdery grey bloom, hanging singly or in twos and threes close to the stem.

Bite one and you will not mistake it for anything else: sloes are eye-wateringly astringent until cooked, sweetened or steeped in gin. They are best after the first cold snap, which softens the skins and the tannins. If the frost hasn't come, pick them anyway and freeze them overnight — the same effect, and easier than waiting.

Don't confuse sloes with bullaces or damsons, which are larger and rounder with a more forgiving flavour, or with the smaller, clustered berries of shrubs such as dogwood. A decent pocket field guide, kept in your coat, will settle the question in a minute or two. When you genuinely cannot tell, leave it alone and enjoy the walk instead.

Three rules that matter more than enthusiasm

• Carry a field guide and use it. Not every hedgerow berry is edible, and a few are distinctly unwell-making. Identify from the whole plant — leaf, stem, thorn and fruit together — not from a single berry held up to the light.
• Pick above dog height. The rule of thumb is roughly waist-high and above. Below that, hedgerows are marked by dogs, splashed by passing traffic and generally less appealing. Higher fruit also gets more sun, so it ripens better and tastes sweeter.
• Avoid busy roads. Keep well away from fast A-roads and heavy traffic. Dust and exhaust deposits settle on low-hanging fruit, and you do not want them in your jelly. If you can hear constant traffic, walk ten minutes further along the footpath and find a quieter stretch.

Alongside those, use common sense: never trespass, ask permission where land is clearly private or commercial, don't strip a hedge bare, and leave plenty for the birds, dormice and other creatures that depend on the same harvest. A quarter from each bush is a generous rule.

Kit, timing and technique

Wear old trousers and long sleeves, and take thin gloves for the brambles and blackthorn. A shallow basket or a rigid tub protects fruit better than a carrier bag, and a walking stick with a hook of tape can pull high branches down to hand height. Secateurs help with stubborn sloe clusters. Take water, a flask and an OS map, and treat the picking as the point of the walk rather than an interruption to it.

Go mid-morning on a dry day, after any dew has lifted. Blackberries are best from late August through September; sloes from October onwards, ideally after a cold night. Take a friend, take your time, and stop for a pub lunch if the route allows — this is slow travel at its most rewarding.

What to do with the haul

Blackberries want very little: a crumble with sharp cooking apples, a quick jam with a squeeze of lemon, or a bramble jelly strained through a cloth overnight. Sloes are almost made for gin — fill a jar, add sugar to taste, cover with gin and shake weekly for three months before straining. They also make a fine, deep-coloured liqueur and a surprisingly good autumn chutney with apples and onions.

Whatever you make, label it with the date and where you picked it. There is something quietly satisfying about a jar in February that carries a memory of a bright October lane.