Cultivation notes

Site and soil

Ideally choose a sunny position sheltered from cold winds and late frosts that can damage the flowers in spring, though modern cultivars show better cold resistance. Blackcurrants can be grown in light shade.

Blackcurrants will tolerate a wide range of soils, but being heavy feeders they prefer moisture-retentive fertile soils that are reasonably well-drained. They can cope with slightly impaired drainage. 

Forms

Blackcurrants crop best on strong young growth made the previous season, so they are usually grown as a stooled  multi-stemmed bush. This involves annual hard pruning of older growth to encourage strong young shoots growing from ground level.

Standard-trained blackcurrants are useful if space is limited. Standards or half-standards are "top worked" bushes – grafted on rootstocks (usually Ribes aureum) with 60cm-1m (2-3¼ft) clear ‘leg’.

Planting

Remove all perennial weeds, then incorporate into the planting area 5cm (2in) dressing of bulky organic material, such as manure based soil conditioner or garden compost. This is particularly important on light soils. Just before planting, fork in a compound fertiliser such as Growmore at 85g per m² (3oz per sq yd).

Buy two-year-old bushes container grown or bare-root FPCS certified stock (The Fruit Propagation Certification Scheme).

Plant bare root plants between October and March, but it is generally best to avoid planting in the middle of winter when the soil is either wet or frozen. Container-grown plants can be planted almost any time, but need regular watering during the dry periods.

Plant both container-grown and bare-root bush plants 5cm (2in) deeper than previously planted; look for the nursery soil mark at base. This will encourage strong shoot development from the base. Plant standards at the same soil depth as previously grown.

Space plants 1.5-1.8m (5-6ft) apart, using the wider spacing for vigorous cultivars.

Pruning at planting

When planting in autumn to early spring cut all shoots back to 2.5cm (1in) above soil level in order to achieve strong growth from the base. Though this seems extreme and the first year’s fruit is lost, this will be beneficial in the long term. On well-developed plants you can retain half of the shoots that will give a small crop. Do not prune container-grown plants hard on planting if planted later in the season when they are actively growing.

Standards do not require hard pruning after planting.

Container cultivation

Blackcurrants generally do not perform well in containers long term due to the growing habit and size of the plants.  However, underperforming containerised plants can recover if planted out into open ground. More compact cultivars such as ‘Ben Sarek’ and ‘Ben Gairn’ are better suited for containers.

Choose a sizeable container about 45cm (18in) wide and deep. Use a soil based compost such as John Innes No. 3, improved with 20-30% by volume multipurpose compost and 10% perlite/sharp-sand/horticultural grit. Alternatively, use peat-free multipurpose compost mixed with about 20% perlite/sharp-sand/horticultural grit.

Mix in a slow-release fertiliser or liquid feed during the summer months. Annually top dress with fresh potting compost. Re-pot after 3-4 years in late winter or early spring. Remove some of the old compost and trim some larger roots on the outside of the rootball.

Feeding and mulching

Feed annually with a general fertilizer, such as Growmore at 100g per square metre (3oz per sq yd) in spring. Weak plants can benefit from an additional high nitrogen feed at 25g per m² (¾oz per sq yd) of ammonium sulphate. Follow feeding with mulching around the base, using a 5cm (2 in) deep layer of organic mulch such as manure-based soil conditioner or garden compost.

Water well in dry weather at ground level rather than overhead. Avoid heavy watering as fruit ripens to prevent skins splitting.

Protect bushes in flower by covering them with fleece or cloth on nights when frost is forecast.

Pruning and training

Bush initial training

Years 1-3: for the first three years after planting, prune lightly in autumn or winter if the growth is strong by removing weak and low-lying shoots, but if growth is weak, prune hard, cutting at least half the shoots back to near ground level.

Established bush

Some pruning can be done at picking time. Prune sprawling branches laden with fruit for stripping back to strong upright growth, but delay the main pruning until winter. Cut out a quarter to a third of the branches each year, aiming to remove old unproductive wood, weak growth and low-lying branches. Make the cuts low down wherever possible to stimulate strong growth from or near the base and remove weak shoots and any dead wood.

Old neglected bushes

Provided they are otherwise healthy, old bushes can be rejuvenated by cutting all but the strongest and youngest branches to within 2.5cm (1in) of ground level in the winter. The subsequent new growth will require thinning to about 12 strong young shoots.

Standards

Remove any suckers growing from the rootstock base of the ‘leg’. It is best to rub off such shoots as soon as seen. On established plants prune back to a stub about a quarter of the oldest shoots to encourage production of new shoots.

Propagation

Blackcurrants can be propagated from hardwood cuttings taken from newly planted certified virus-free plants in mid-autumn to winter. The cuttings should be 20cm (8in) long.

Cultivar Selection

Early and early- to mid-season

‘Ben Connan’ AGM: Large berries, medium long string. Heavy crops. Compact habit. Good resistance to mildew and leaf curling midge. Early season. Plant 1.5m (5ft) apart.

‘Ben Gairn’: Compact. Early flowering and early ripening, but resistant to cold damage. Good uniforms crops of quality, large, juicy fruit. Suitable for closer planting 1-1.2m (3¼-4ft) apart.

'Big Ben' AGM: Fairly vigorous medium-sized bush. Fruit large and easy to pick and good yields. Showing resistance to mildew and leaf spot. Fresh fruit flavour pleasant to quite sweet; rich when cooked. Good all-round cultivar. Plant 1.5m apart. Early to mid-season.

‘Boskoop Giant’: Large sweet berries. Flowers early, crops heavily. Bushes are very vigorous - not suitable for small gardens. Early. Plant 1.8m (6ft) apart.

‘Ebony’: Moderately vigorous with open and slightly spreading growing habit. Good crops of sweet fruit that can be considered for dessert use. Resistance to mildew. Early ripening. Plant 1.2m (4ft) apart.

Mid- and mid- to late-season

‘Ben Hope’: Fairly vigorous with upright habit. High yields of medium sized berries with a very good flavour. Perhaps better suited for more challenging growing conditions. Shows resistant to mildew, leaf spot and gall midge. Plant 1.5m (5ft) apart. Mid-late season.

‘Ben Lomond’: Flavour is good, but acid. Berries large, trusses short. Cropping good. Bush has upright form, spreads a little with crop. Flowers late; some resistance to frost. Some resistance to mildew. Mid-late. Plant 1.5m (5ft) apart.

‘Ben Sarek’: Acid flavour, large berries on short stalks. Crops well. Small, compact bush of medium vigour. Some tolerance to cold and frost and resistance to mildew and leaf-curling midge. Suitable for the small garden. Needs support while in crop to prevent sprawling. Mid-late. Plant 1-1.2m (3¼-4ft) apart.

‘Wellington XXX’: Berries sweet, medium to large, with a rough skin. A heavy cropper. Growth is vigorous and spreading. Mid-season. Plant 1.5-1.8.m (5-6ft) apart.

Late season

‘Baldwin': Sharp flavour. Tough skin. Berries medium, hang well without splitting. Cropping moderate to good. Bush medium, fairly compact. Suitable for small garden. Late. Plant 1.5m (5ft) apart.

‘Ben Tirran’: Strong, upright growth, but fairly compact. Flowers late in the season. High yields of medium-size berries. Great for culinary purposes. Showing some mildew resistance. Plant 1.2-1.5m (4-5ft) apart. Late season – good for extending the cropping season.

Jostaberry (gooseberry and blackcurrant hybrid)

Easy to grow and generally trouble free, jostaberry is very vigorous shrub with and an upright growing habit that needs plenty of space. It has a unique flavour that combines those of both parents. Growing requirements same as for blackcurrants. Plant at least 1.5m (5ft) apart.

Josataberry is gown as a multi-stemmed shrub. In the first year after planting in late winter prune the stems back by half to three quarters to an outward facing bud. Subsequent pruning is as for blackcurrants.

Problems

Look out for the small, distorted and crumpled foliage of blackcurrant gall midge and the enlarged rounded buds in winter that fail to develop in spring which indicates blackcurrant big bud mite. Currant blister aphid is very common, leading to puckered leaves at the shoot tips, which are often reddish or yellowish green. Pale yellow aphids may be seen on the lower leaf surface.

Pick ripe fruit before they are taken by birds.

Blackcurrants can suffer from gooseberry mildew with white mildew growth (turning brown with age) on young shoots and fruits.

Sunscald – when the ripening berries are to direct sunshine during periods of very hot weather the berries can develop orangey patches of damaged skin tissue. The damage is more prominent on the sunny side and parts of the fruit exposed to sun. The damaged fruit usually drops off.

Jostaberry foliage can suffer from crinkling/russetting. This is considered to be a genetic disorder as jostaberry is a cross between a gooseberry and blackcurrant. It does not seem to affect the general vigour of the plant. Observations suggest that this disorder can be made worse by frost/cold damage in the spring.