How to grow Blackcurrants

How to grow Blackcurrants

The popularity of these deciduous bushes is probably due to their self-fertile nature (so you only need one bush on the plot to supply lots of fruits), the fact that they tolerate most soils (but not dry or badly-drained ground) and are hardy in all parts of the country.

They are also extremely robust and very reliable. Just about every grow-your-own gardener will know of someone who has inherited or grown a blackcurrant that regularly forms a crop of fruits despite years of neglect.

How big do blackcurrant bushes grow?

If you grow blackcurrants ‘by the book’ and plant and prune them properly, you will get more fruits and they will be of a better quality. You will also be able to restrict the bushes to a height and spread of 120–150cm, meaning they can be grown in fairly small spaces. They should stay productive for at least a decade and you can expect 10–15 pounds of fruit per plant each season.

If you have never grown a blackcurrant before, or just want to expand your collection, then early winter is an ideal time of the year to plant some new specimens in the fruit garden. It’s also a good opportunity to prune established specimens to ensure a heavy crop next year.

A sheltered spot with a reasonably fertile, moisture-retentive and well-drained soil is preferable for blackcurrants. If it has a slightly acidic pH (around 6–6.5 – testing kits are cheap and widely available) that’s all the better, but it’s not essential. Avoid placing them in frost pockets, as a late frost can damage the flowers and lead to a smaller harvest.

Although blackcurrants will tolerate partial shade, the fruits taste better when exposed to plenty of sunshine, and shaded bushes may become weak and leggy. A few weeks before planting, always clear the ground of weeds, especially perennial types such as dandelions or docks, and enrich the soil with plenty of well-rotted manure or compost.

You’ll find most blackcurrant bushes for sale in garden centres as bare-rooted plants. The ideal time for getting them in the ground is late autumn to early winter. Any time up to mid-March is also fine (as long as the ground isn’t waterlogged or frozen) but they will have less time to settle before starting into growth.

Blackcurrants grown in containers can also be purchased from garden centres or nurseries and planted throughout the year – but whenever possible, opt for the autumn, early winter or spring.

Whatever the month, planting should always be avoided if the ground is very dry, frozen or waterlogged due to heavy and persistent rain or poor weather conditions. For the best results, select bushes that are certified as virus and disease-free and have at least three obvious stems.

Spacing requirements when planting blackcurrant bushes

Space the bushes 1.5m apart in the ground, and set them about 5cm deeper than they were planted in the nursery – an obvious soil mark is usually visible on each plant. This will encourage the stem bases to form roots as well, and eventually give the bushes more support.

How to prune blackcurrant bushes

Annual pruning should begin two years after an autumn planting, as established blackcurrants produce by far the greatest part of their crop (and the best fruits) on the previous season’s stems.

Regular cutting-back also prevents the plants becoming unkempt and overgrown, a state which would otherwise encourage pests and diseases to make inroads and also make harvesting difficult.

The ideal time to prune blackcurrants is between November and March as this is the plants’ dormant period. If you’re unsure how to cut back blackcurrant bushes, it’s not too challenging.

First, remove any dead, diseased or damaged stems, as well as those that are weak and spindly or crossing in the centre of the plants. Next, cut back one-third of the oldest stems (these are usually thicker and darker in colour) to ground level, as this will leave enough room for healthy replacement stems to grow.

As you can imagine, with the need to cut it back so regularly, a blackcurrant cordon isn’t something that is advisable.

When carrying out pruning work always use a pair of clean and sharp secateurs (or handheld loppers) and do not leave any snags on the stems, as they can be a likely point of infection for various diseases.

Afterwards, clear weeds from the area and surround the base of each bush with a thick mulch of garden compost.

Blackcurrant pests and diseases

Unfortunately, currants are sometimes sought out by hungry birds (especially pigeons) and the developing and mature fruits may need protecting by covering with a sheet of fine netting. Alternatively, protect from these blackcurrant pests by dangling old CDs from string nearby or hang thin strips of recycled tin foil from the stems – these will glint in the sunlight and rustle in the slightest breeze to frighten away any passing birds.

If you’re finding leaf curl on blackcurrant bushes, it’s likely that you might have an infestation of gall midge, which can cause leaves to dry up and die. Adult midges that have been over-wintering in the ground during colder months, emerge from the soil during late spring, and lay eggs in the folds of unfurled leaves.

The larvae feed on leaves and shoot tips, which if the infestation gets bad, can severely damage new growth. Digging over the ground around the bush when dry from spring through to autumn may be one non-chemical method for keeping numbers down, by subjecting pupae to drying conditions, opting for resistant blackcurrant cultivars like ‘Ben Connan’ and ‘Ben Sarek’ may also help.

One of the major blackcurrant diseases is gooseberry mildew, though as its name suggests is more of a problem for gooseberry plants. Leaves and stems develop a powdery mildew, impacting growth and ripening of blackcurrant fruits. Stay vigilant to this fungal disease and prune and cut out any infected stems that show symptoms, ensuring blackcurrant bushes are spaced a considerable distance from one another will improve air circulation and reduce risk.