The blackcurrant (Ribes nigrum), also known as black currant or cassis,[a] is a deciduous shrub in the family Grossulariaceae grown for its edible berries.

Bunches of small, glossy black fruit develop along the stems in the summer and can be harvested by hand or by machine.

The leaves are alternate, simple, 3 to 5 centimetres (1+1⁄4 to 2 inches) broad and long with five palmate lobes and a serrated margin.

[10] Blackcurrants can grow well on sandy or heavy loams, or forest soils, as long as their nutrient requirements are met.

[11] The blackcurrant requires a number of essential nutrients to thrive; nitrogen provides strong plant growth and stimulates the production of flower sprigs; phosphorus aids growth, the setting of fruit and crop yield; potassium promotes growth of individual shoots and increases the weight of individual fruits; magnesium is a constituent of chlorophyll and helps increase yields through interaction with potassium; calcium is required for cell division and enlargement and is particularly important for young plants and buds.

The blackcurrant is a gross feeder and benefits from additional nitrogen, and phosphatic and potash fertilisers should also be applied annually.

[11] A balanced artificial fertilizer can be used and a 10-10-10 granular product can be spread around the bushes at the rate of 100 to 240 grams (3+1⁄2 to 8+1⁄2 ounces) per plant.

Newly planted bushes should be pruned severely, cutting all shoots back to two buds above ground level.

The blackcurrants are placed into half tonne bins and to minimise stoppage time, some machines have cross conveyors which direct the fruit into continuously moving trailers in the adjoining row.

[17] White pine blister rust (Cronartium ribicola) needs two alternate hosts to complete its life cycle.

Currant and gooseberry leaf spot (Drepanopeziza ribis) is another disease of blackcurrants, but it is not usually a serious problem as most cultivars now have some resistance.

[11] The blackcurrant leaf midge can cause browning, crimping and distortion of leaves at the tips of shoots but it is seldom a serious problem.

[18][19] During the 20th century in Europe, much hybridisation work has been carried out in order to reduce the plant's susceptibility to disease and frost and also to increase yields.

[20] In Britain the Scottish Crop Research Institute was tasked with developing new varieties suitable for growing in the north of the country.

Frost tolerance was improved by selecting for late flowering and genetic research identified genes involved in resistance to gall mite and the blackcurrant reversion virus.

[19] Varieties producing green fruit, less strongly flavoured and sweeter than typical blackcurrants, are cultivated in Finland, where they are called "greencurrants" (viherherukka).

[24] In Poland, the Research Institute of Horticulture has done work on improving the blackcurrant with regard to disease and pest resistance, fruit quality, adaptations to local conditions and mechanical harvesting.

Breeding programmes are concentrating on yield, large fruit size, consistency of cropping and upright habit.

Back-crossing these varieties to a parent have produced new strains such as 'Titania' that have a higher yield, better disease resistance, are more tolerant of adverse weather conditions and are suitable for machine harvesting.

[27] Two new releases from a black currant breeding program in British Columbia, Canada, 'Blackcomb' and 'Tahsis', were selected for their immunity to white pine blister rust and their frost tolerance.

[32] During World War II, most fruits rich in vitamin C, such as oranges, became difficult to obtain in the United Kingdom.

[33] In Britain the commercial crop is completely mechanised and about 1,400 hectares of the fruit are grown, mostly under contract to the juicing industry.

[25] As of 2017[update], major cultivation efforts to improve fruit characteristics occurred in Scotland, New Zealand, and Poland.

Since the American federal ban curtailed currant production nationally for nearly a century, the fruit remains largely unknown in the United States and has yet to regain its previous popularity to levels enjoyed in Europe or New Zealand.

Owing to its unique flavour and richness in polyphenols, dietary fibre and essential nutrients, awareness and popularity of blackcurrant is once again growing, with a number of consumer products entering the U.S.

The purée can be used to make blackcurrant preserves and be included in cheesecakes, yogurt, ice cream, desserts, sorbets, and many other sweet dishes.

The exceptionally strong flavour can be moderated by combining it with other fruits, such as raspberries and strawberries in summer pudding, or apples in crumbles and pies.

Blackcurrants are a common ingredient of rødgrød, a popular kissel-like dessert in North German and Danish cuisines.

[46] In Russia, blackcurrant leaves may be used for flavoring tea or preserves, such as salted cucumbers, and berries for home winemaking.

Sweetened vodka may also be infused with blackcurrant leaves making a deep greenish-yellow beverage with a tart flavor and astringent taste.