Soil and Situation. Black currants succeed on a wide variety of soils and do not dislike moist conditions, provided their roots do not stand in stagnant water during winter. Flowers are produced early and are liable to be damaged by frost, so hollows which are likely to be frost traps should be avoided. Soil must be dug thoroughly; manure or compost may be incorporated at 1 cwt. to 8 sq. yd., as black currants like rather rich conditions. Lime is not essential.
Planting. This may be done at any time from late October until mid-March, provided soil is working freely. Roots. are fine and fibrous, and soil must be carefully worked round and between them. The uppermost should be just covered. Make thoroughly firm. Growth is vigorous and at least 5 ft. should be allowed between the bushes.
Forms of Training. Black currants are almost invariably grown as bushes. It is no disadvantage if these are legless, i.e. without main stems and with many shoots coming through the soil, direct from the roots. Very occasionally the plants are trained in fan formation against fences or espaliers.
Pollination. All black currants are fully self-fertile and also inter-fertile. It is therefore possible to plant one variety only or any combination of varieties and obtain good crops. Poor fertilization is common, but is due to frost or lack of insects to secure pollination, not to sterility. The trouble is known as ‘running off,’ as it is usually the end flowers of each truss that fail to set. More bees or hand fertilization with a camel-hair brush and a more sheltered position are the remedies.
Pruning. All work can be done in winter, between October and February, or, if preferred, as soon as the crop has been gathered. The object is to eliminate as much as possible of the growth that has just carried fruits without sacrificing strong young shoots on which the following year’s crops will be borne. It does not matter if these come right from the roots. After planting, all growth should be cut back to within 2 or 3 in. of soil level.
Picking. Where fruits are required for home use only, it often pays to pick individual berries, as those nearest to the stem ripen before those at the tips of the truss. For exhibition, fruits must be shown on the truss, and so these are picked whole when all berries are black, but before the biggest start to split. Storing is impracticable, but black currants bottle excellently.
Routine Feeding. Mulch each March with well-rotted dung or compost at 1 cwt. to 8-12 sq. yd. Give sulphate of potash at oz. per sq. yd. each October. If dung is not available, substitute nitrate of soda, Nitro-chalk, or sulphate of ammonia at 2 oz. per sq. yd., and follow with a mulch of grass clippings.
Routine Pest Control. Usually unnecessary, as foes are dealt with as noted. If big bud mite is troublesome, spray in March with lime sulphur at twice normal winter strength. The ideal time for application is when the most forward leaves are an inch across. Examine bushes each July for reversion and burn any affected.
Propagation. By cuttings taken during October and November. Cuttings are from 8 to 15 in. in length and prepared from well-ripened growths of the current year’s formation. Trim each immediately below a joint and insert firmly 4 in. deep in any well-drained soil and reasonably sheltered position. Cuttings should be 6 in. apart in rows 18 in. apart. Transplant to permanent positions after one year’s growth.
Varieties of Black Currant. Amos Black, Aug.; Baldwin, Aug.—Sept.; Blacksmith (Tinker), Aug.; Boskoop Giant, June—July; Daniel’s September, Aug.; Davison’s Eight, Aug.; Goliath (Victoria, Edina), Aug.; Laxtons Giant, July ; Mendip Cross, July; Seabrook’s Black, Aug.; Wellington XXX, Aug.; Westwick Choice, July—Aug.; Worcesterberry is an American hybrid and is grown like a gooseberry.
(The months are those in which the variety normally ripens.)