Blackcurrants Garden Myths: What Holds Up

“Cut out all the old wood on blackcurrants each winter”

Blackcurrants fruit on the previous season's growth, not on very old wood. The advice is to prune in winter by removing about a third of the oldest stems at ground level, not everything. Cutting out all old wood leaves only young growth that has not fruited yet.

Our read The confusion comes from raspberries. Summer raspberries fruit on last year's canes and old canes are cut out. Blackcurrants are the opposite: the one and two-year-old wood carries the crop.

What to do: Cut out about a third of the oldest, darkest stems each winter at ground level, leaving the younger wood standing. Aim for a bush with stems of different ages so some are always coming into bearing.

“Blackcurrants will grow anywhere — just stick them in a corner”

Blackcurrants are tough plants, but they need full sun, rich soil and consistent moisture to produce a worthwhile crop. A sheltered, sunny site with fertile, moisture-retentive soil is what's advised. A bush in a shady, dry corner produces leaves and almost no fruit.

What to do: Give blackcurrants a sunny, sheltered position with soil that holds moisture. Mulch thickly in spring to keep the roots cool and moist. The difference between a pampered bush and a neglected one is not survival — it is kilos of fruit.

In Scotland: Scotland grows some of the world's best blackcurrants for Ribena, and the climate suits them. The soil condition is the variable: heavy Central Belt clay holds moisture well if improved with organic matter, but pure clay starves the roots.

“Big bud on blackcurrants means dig the bush out — it's finished”

Big bud mite is a serious pest but a light infestation is manageable. The advice is to pick off and destroy affected buds by hand before they open in spring. Only a severe infestation warrants removal.

Our read Big bud mite is the blackcurrant pest everyone has heard of and the one most likely to trigger an unnecessary grub. A few swollen buds in spring is a nuisance, not a death sentence.

What to do: Pick off swollen, rounded buds before they open in spring and bin them. If most of the bush is affected, replacement is the right call, but give the plant a season first.

“Blackcurrants need full sun or you won't get a crop”

Blackcurrants tolerate partial shade better than almost any other soft fruit. They can be grown in partial shade, and a north-facing wall that gets morning sun will produce a worthwhile crop.

What to do: A spot that gets morning sun and afternoon shade is fine for blackcurrants. They will crop less heavily in deep shade, but a few hours of direct sun is enough for a family picking.

In Scotland: The partial-shade tolerance is a genuine Scottish advantage. A north-facing border that grows little else can still give you blackcurrants, and the cooler position delays flowering enough to miss the last frosts.

“Blackcurrants fruit on new wood, so cut all the old stems out every winter”

Blackcurrants fruit most heavily on one-year-old wood, but two- and three-year-old stems also carry fruit. Removing only the oldest stems and leaving younger wood gives a more consistent crop than stripping the bush to the ground.

What to do: Prune in winter by removing about a third of the oldest, darkest stems at ground level. Leave one- and two-year-old wood standing. This renews the bush gradually rather than forcing it to rebuild from scratch each year.

In Scotland: A Scottish winter is long enough that a hard-pruned blackcurrant sits leafless for months before regrowth starts. Gradual renewal keeps more of the bush's framework in place and gives an earlier crop the following summer.

“Blackcurrants are self-fertile, so pollination isn't something you need to think about”

Self-fertility is real but the practical conclusion doesn't follow. University extension research on black currant pollination found self-pollination produced the lowest fruit set of any tested condition, while cross-pollination between cultivars and visits from insect pollinators such as bees measurably increased fruit set, yield, and berry size.

What to do: One bush will fruit, but don't assume pollination is a non-issue. Give bushes an open, insect-accessible position rather than a netted or enclosed corner during flowering, and where you have room, a second cultivar nearby will noticeably improve cropping over a single bush on its own.

“Dig sand or grit into heavy clay to break it up”

The quantities involved make this hopeless at garden scale. Meaningfully diluting a soil that is 40 per cent clay takes around 250kg of grit or gravel per square metre. A barrowload does nothing, and adding modest amounts can destabilise the structure and leave the ground harder to work than before you started.

What to do: Add bulky organic matter instead: manure or composted bark, dug in generously. Raise beds to lift roots above the wet, and consider not digging at all. Those three do what the sand was supposed to do, and they compound each year rather than needing repeating.

In Scotland: Heavy clay runs right through the Central Belt, so this is one of the most expensive mistakes a Scottish grower can make. Two tonnes of grit for a small bed is not a purchase anyone makes twice.

“On clay, dig a big hole and fill it with grit so the roots drain”

This does the opposite of what it promises. A free-draining pocket surrounded by clay has nowhere to drain to, so it fills and holds water like a bucket sunk in the ground: the hole becomes a sump and the roots sit in it and rot.

What to do: Plant at the same level as the surrounding soil and improve the whole bed rather than one hole. Where drainage is genuinely bad, raise the bed so the roots sit above the wet instead of in a pocket of it.

In Scotland: Worth knowing here because our rainfall keeps that pocket topped up. In a dry climate a sump might drain between downpours; through a Scottish autumn it simply stays full.

“You have to dig the ground over each year to keep the soil fertile”

Digging works against fertility rather than for it. Turning the ground releases soil nitrogen and damages the soil's biology. The structure that fungi, worms and roots build up over a season is undone every time the spade goes through it.

What to do: Leave the ground alone and feed it from the top. Spread compost or well-rotted manure on the surface and let the soil life pull it down. Dig only where you actually need to, such as lifting root crops or clearing perennial weeds.

In Scotland: There is a practical bonus here: undug ground carries weight better and warms marginally earlier in spring than freshly turned wet soil, which matters when the season is already short.

“Peat-free compost doesn't grow plants as well as the peat stuff”

This was a fair complaint a decade ago and it has not aged well. Peat-free quality has greatly improved in recent years, and dedicated research has found some carnivorous plants grow better in peat-free mixes than in peat. What is true is that peat-free behaves differently: the watering and feeding requirements are not the same, because the ingredients have different physical and chemical properties from peat.

Our read Most bad experiences with peat-free are a watering problem rather than a compost problem. It dries differently, so the habits you built on peat will let you down for a season until you adjust.

What to do: Read the bag rather than assuming, since feeding and watering advice genuinely varies between mixes. Buy fresh: old stock breaks down and performs worse regardless of what it is made of. If one brand disappoints, try another rather than writing off the category.

In Scotland: This matters more here than almost anywhere in Britain. Scotland holds a great deal of the UK's peat, those peatlands are major carbon stores, and peat-based compost comes out of them. The performance excuse for buying peat no longer holds up.

“Plants do better in pots than in the ground”

A container limits how far roots can spread and cuts the plant off from the reservoir of moisture and nutrients that open ground provides, increasing the need for both watering and feeding. You are taking on work the soil would have done for free.

Our read Pots are a solution to a problem, not an upgrade: no ground, bad drainage, a crop that needs containing, or somewhere warm against a wall. Chosen for those reasons they are excellent. Chosen by default they make the job harder.

What to do: Use the ground where you have it. Where you do use pots, go bigger than feels necessary, expect to water far more often, and feed through the season because there is no soil reserve to draw on.

“Strong-smelling plants confuse pests and hide your crop”

This is the theory underneath half of every companion planting chart, and it is the wrong mechanism. Research at Wellesbourne, Britain's long-standing centre for brassica and carrot pest work, found that insects hunting a host land on green and avoid bare brown soil. Colour, size and shape decide where they settle. Artificial green plants, and even green paper releasing nothing at all, disrupt them as well as living companions do, and aromatic plants perform no better than bland ones.

What to do: Stop choosing companions by scent. If ground cover is what disrupts the pest, the useful question is whether something low and green grows between your rows, not whether it smells of anything.

“Watering in sunshine scorches the leaves”

Water droplets do not focus sunlight enough to burn foliage. Scorch on new plants comes from insufficient hardening off far more often.

What to do: Water whenever the plant needs it. Watering at ground level rather than over the leaves is still worth doing, but for disease and evaporation reasons, not for scorch.

In Scotland: Rarely the limiting factor here anyway, though it matters under cover, where watering habits drive humidity and therefore disease.

“Coffee grounds acidify your soil and feed your plants”

Grounds do contain nitrogen, phosphorus, potassium and magnesium, so the feeding half is not baseless. The acidifying half is not: their effect on pH is very minor and temporary. Spread thick they cap the soil and block water and air, and residual caffeine can suppress root and shoot growth.

What to do: Put them in the compost bin rather than straight on the bed. If you actually need to change pH, that is a job for lime or sulphur guided by a soil test, not for coffee.

In Scotland: Most Scottish soils are naturally acidic already, so the acidifying claim solves a problem you probably do not have and may worsen one you do.