For blackcurrant liqueur, see Crème currant leaf cassis. Grossulariaceae grown for its edible berries. It is winter hardy, but cold weather at flowering time during the spring may reduce the size of the crop.
Bunches of small, glossy black fruit develop along the stems in the summer and can be harvested by hand or by machine. The raw fruit is particularly rich in vitamin C and polyphenols. Blackcurrants can be eaten raw but are usually cooked in sweet or savoury dishes. Ribes nigrum is a medium-sized shrub, growing to 1. All parts of the plant are strongly aromatic. Each flower has a hairy calyx with yellow glands, the five lobes of which are longer than the inconspicuous petals.
There are five stamens surrounding the stigma and style and two fused carpels. An established bush can produce about 4. Polyphenol phytochemicals present in the fruit, seeds and leaves, are being investigated for their potential biological activities. The blackcurrant is native to northern Europe and Asia.
Cultivation in Europe is thought to have started around the last decades of the 17th century. Blackcurrants can grow well on sandy or heavy loams, or forest soils, as long as their nutrient requirements are met. They prefer damp, fertile but not waterlogged ground and are intolerant of drought. Two-year-old bushes are usually planted but strong one-year-old stock can also be used. Planting certified stock avoids the risk of introducing viruses.
On a garden scale the plants can be set at intervals of 1. An annual spring mulch of well rotted manure is ideal and poultry manure can also be used but needs prior composting with straw or other waste vegetable material. Spent mushroom compost can be used but care should be taken as it often contains lime and blackcurrants prefer slightly acidic soils. Weed growth can be suppressed with an organic mulch such as sawdust, bark, mushroom compost or straw, heavy plastic topped with an organic mulch cover or landscape fabric. Blackcurrant fruit is borne primarily on one-year-old shoots. Newly planted bushes should be pruned severely, cutting all shoots back to two buds above ground level. This gives the plant a chance to get properly established before needing to put its energy into producing fruit.
The general rule when pruning is to remove all weak shoots and those growing out sideways which may get weighed down when fruiting. On a garden scale, the berries should be picked when dry and ripe. Commercially, most harvesting is done mechanically by straddle harvesters. These move continually down the rows, straddling a row of bushes, shaking the branches and stripping off the fruit.