Soft fruit is one of the great rewards of an allotment. A well-tended blackcurrant bush will crop for fifteen years or more, and a raspberry row keeps going as long as you feed and water it properly. The good news is that currants, gooseberries, raspberries and their blackberry cousins are not fussy plants — they want a decent meal in spring, a blanket of organic matter over their roots, and a steady supply of water while the fruit swells.

Start With a Balanced Feed in Early Spring

Feed established bushes in late February or March, just as the buds begin to break and the soil starts to warm. A balanced general fertiliser is exactly right at this stage — Growmore or blood, fish and bone both do the job. Scatter it evenly across the root area, out as far as the branches reach. That is where the feeding roots live, not tight against the trunk. Then tickle it into the top few centimetres with a hand fork. Soft fruit roots are shallow, and deep digging does far more harm than good.

• Blackcurrants: the hungriest of the lot — 70–100g, or two good handfuls, per bush
• Redcurrants and whitecurrants: 50–70g per bush
• Gooseberries: 50–70g per bush
• Raspberries: 70g per metre of row, scattered along the line of canes
• Blueberries: ericaceous feed only — a general fertiliser will do them no favours

Potash: The Fruit-Making Mineral

Balanced feed gets the bush growing; potash gets it fruiting. From May onwards, a dressing of sulphate of potash — roughly 30g per square metre, or a small handful per bush — encourages bigger, sweeter, firmer fruit. If the season is wet, a second light dressing in June is worth the effort. Wood ash from untreated timber is the traditional alternative, though it should never go near blueberries, which need acid soil.

Just as important is what you don't give them. Avoid rich nitrogen feeds after midsummer. They push out soft, sappy growth that will not ripen before the frosts and makes the bush more vulnerable to disease.

Mulch With Well-Rotted Manure

Once the fertiliser is in and the soil is damp and beginning to warm, mulch. A 5–8cm layer of well-rotted farmyard manure, garden compost or spent mushroom compost does four jobs at once: it feeds slowly, holds moisture, smothers weeds and keeps the worms working. Leave a clear collar of about 10cm around each stem — piling mulch against the wood encourages rot and soft growth.

Spring is the ideal moment, but an autumn mulch after leaf fall works well too and protects shallow roots through hard frosts. Never use fresh manure, which can scorch young roots. Simply top the layer up each year and let the worms pull it down.

Water Consistently as the Fruit Swells

This is where most disappointing crops are lost. A dry spell in May and June, just as flowers set and fruit begins to swell, will cost you more currants than any shortage of feed. Aim to soak the ground thoroughly rather than splashing a little on each day.

• Mature bushes: 10–20 litres a week in dry weather, poured slowly at the base
• Raspberries: shallow-rooted and thirsty — around five litres per metre of row every two or three days in a dry spell
• Timing: water in the morning, at soil level, so the foliage stays dry and fungal problems stay away
• Consistency: a parched spell followed by a soaking splits ripening fruit and drops currants, so keep the supply even

A good mulch will halve the amount of watering you need, and a leaky hose laid along a raspberry row is money well spent.

Crop-by-Crop Pointers

• Blackcurrant: the heaviest feeder of all. Feed generously, water well, and prune out about a third of the oldest wood each winter — the fruit comes on young growth.
• Redcurrant and whitecurrant: lighter feeders. Too much nitrogen gives you leaves instead of trusses, so lean on potash in May and June.
• Gooseberry: potash for clean, large fruit. An overfed, congested bush invites mildew, so keep it open in the middle.
• Summer raspberries: feed in March, water hard through July, then cut out the fruited canes once they finish.
• Autumn raspberries: cut every cane to the ground in February, then feed and mulch straight away — they fruit on the new season's growth.

A Simple Yearly Rhythm

• Late February to March: balanced feed, then mulch
• May to June: sulphate of potash; water steadily as the fruit swells
• July to August: keep watering and pick regularly to keep plants cropping
• September to October: tidy, prune, and top up the mulch for winter

Get those four steps roughly right and your bushes will reward you for years — punnets of currants for the freezer, gooseberries for crumbles, and raspberries eaten warm off the cane before they ever reach the kitchen.