How to Grow Blackcurrant Plants – Blackcurrant Bush
For some reason or another, blackcurrant plants have come to be looked upon as an everlasting fruit bush and I have come across moss-covered bushes in gardens whose owners have proudly assured me that they must be at least 36 to 40 years old. All plants including trees, have a definite age limit and with a blackcurrant bush, the average worthwhile fruiting age is 12 years. As a general rule they should be dug up after this and replaced. There is, however, nothing wrong with taking cuttings from healthy stock and turning them into new bushes.
Blackcurrant Plant Varieties and Propagation
New varieties of blackcurrant plants are obtained from seed, but for all practical purposes the usual way of increasing blackcurrants is either by cuttings, softwood cuttings in July or hardwood in late summer, or by division. The latter method is a useful one as fruiting blackcurrant bushes can be obtained more quickly provided the stock is healthy. The method is to trim up a big bush and then stand in the middle of it, pressing out the side growths and half breaking them belowlevel. Soil is then thrown into the middle and trodden down firmly, further pushing out the partially broken portions. In about twelve months these will root into the mound of soil in and around the blackcurrant bush and the whole can be split up with a spade or mattock. The advantage claimed for this method is that a better stool bush is produced.
Blackcurrant plants fruit on both the old and the new wood but better, bigger and more fruits are produced on the young growth formed the previous year and naturally the stronger and bigger the growths the more berries they will carry. New growths form at any point on all wood, but the higher up they form the shorter they are and in very old unpruned bushes they may be no more than 4 to 6 inches long whereas a better length would be 3 to 4 ft. The whole aim is the production of new stems from the base, and this formation is called a stool. Gooseberries, red and white currants differ from blackcurrants although they are members of the same family as they are trained and grown on a single stem called a leg.
The training starts at propagation. In the case of plants required to be grown on a leg, the lower buds of the cutting are removed but where a stool formation is desired, all the buds are allowed to remain on and the cutting is inserted with buds below soil level. Of the two types of cuttings the hardwood cuttings are easiest to root and are less trouble, but the one advantage of taking softwood cuttings about 3 or 4 inches long in July, is that if there is danger of big bud mite, these cuttings can be rendered virtually immune by soaking for a few minutes in malathion. The big bud mite is a microscopic insect which moves very slowly, in fact the young growth grows faster than the mites move. However, they can be blown onto new growth, carried piggy-back by insects or on the feet of birds so it is wiser to wash the cuttings thoroughly in a good insecticide. This means that the stock at least starts clean.
Pruning Blackcurrant Bushes
Blackcurrant plants should be pruned as soon as the crop has been gathered but I hold no brief for the method of cutting off fruit rods and carrying them away somewhere else to strip off the fruit.
New and old wood more than three years of age can be distinguished by colour, the older wood being black or almost black and the younger wood a light greenish brown. As a general rule sufficient cuttings may be had from the young growths at the tips or half way up old wood but they should be no thinner than an ordinary pencil. Several cuttings of about 8 in long or even slightly less may sometimes be taken from one good young growth.
To distinguish the top and bottom of a cutting, which may be of almost equal diameter, cut straight across below a bud for the base and for the top cut at an angle of 45 degrees.
Planting and Growing Blackcurrant Plants
Blackcurrant plants will grow in almost any but soils but to give their best, they require an annual mulch of farmyard manure with two or three applications during the growing season of a nitrogenous fertiliser such as sulphate of ammonia. In the ordinary garden, blackcurrant plants form an excellent wind break and should be placed so that they do not shade other crops for, under good conditions, they can run up to 6 ft in height.
Planting should be at 5 ft intervals and for garden use I prefer to plant one-year-old blackcurrant bushes in preference to the older ones. If these are then cut down to within 4 inches of the ground, excellent new growths spring from the base. For the home garden the large sweet variety Boskoop Giant is still really good. For the exhibitor, Laxton’s Giant with berries almost as big as a cherry is superb. Westwick Choice has a high vitamin content, and for a good general purpose berry, try Mendip Cross.
Pests and Diseases
Aphids and big bud mite are the two worst pests of the blackcurrant plant and, for small plantings, regular and systematic picking off and the destruction of the buds is as good a way of controlling big bud condition as any that I know. Aphids can be controlled by spraying with malathion, paying particular attention to young shoots and the undersides of the leaves.
I think the most important thing with any fruit bush, and particularly with blackcurrants, is that if they develop an unhealthy look and produce poor or small fruit then do not waste time and money treating them but dig them up and replant. By the time the trouble has been identified and treated, some of the other bushes may be infected as well. With the commercial grower the position is different. He is expected to know something about the blackcurrant bushes, but the home gardener cannot possibly be expected to know everything that can happen to his fruits.