Although we have many varieties of the cultivated currants in Europe and America, all except what are known as black currants belong to one species (Ribes rubrum). With the red and white currants there has been no intermingling of species, and when we grow our garden varieties from seed they vary but little. If we plant the seed of such old varieties as Red and White Dutch and Victoria, we have a very near reproduction of the parents, except that the color may vary. Those who have planted the seeds of the Fay report that nearly half of the seedlings bear white or yellow fruit. Professor Card says: "Perhaps through it's long sojourn in the low countries the currant has inherited something of the staid Dutch qualities of the inhabitants, and does not readily depart from long-established customs." But no cultivated fruit responds more promptly to good treatment in the way of culture, manure, and proper pruning. In the same vicinity we find the old varieties differing so much in size and quality as to lead to belief that they were distinct varieties.
Botanists say that the wild red currants of this continent belong to the species found over Europe. But as yet we have no cultivated native variety of value. All our varieties have been imported from Europe or grown from seed of the foreign varieties.
The fruit is each year becoming more general in demand in our markets and its commercial growing is being extended. In the home gardens, with common care, it bears good fruit when thirty or more years old. As a dessert fruit it is not equal to the strawberry, but it comes at a different season, and such varieties as the White Grape require no more sugar to make them palatable than the strawberry. The currant jelly is also a home delicacy that is refreshing and wholesome throughout the year.
The currant is not grown from seed except when new varieties are wanted. But it is interesting to plant the seed in a small way to watch the varied shades of coloring of the fruit of the seedlings. The stratified (5. Seed-stratification) seeds grow readily if planted very early in the spring. If buried outside, the soil is usually in condition to plant by the time the buried seeds can be taken up. We have planted currant- and goose-berrv-seed in March when not more than two inches of the surface soil was thawed. If not planted early the seed sprouts in the sand with which it is mixed.
The almost invariable method of propagation is from cuttings of the young wood planted in the fall (58. Fall-planting of Cuttings). Cuttings made and set in August, or as soon as the leaves are ripe, will root during the fall, as shown in Fig. 81. In the figure the cutting is shown in erect position, but it is best to plant all cuttings as shown by figure in section (58).
Layers put down in spring will also be well rooted in the fall, if the shoots are twisted at the point where buried (52. Summer Layering).
Fig. 81. - Currant cutting planted in August and rooting the same season.
The currant is usually grown in bush form. In this stool form they throw up shoots from the crown which can easily be shaped by pruning. But along walks and in well-kept places the tree form is often adopted. This is effected by cutting off all the buds of the cuttings except at the top, and when the top bud starts rub off all shoots but one and train that upward, as noted in section (265. Pruning and Training).
The currant will grow and bear under neglect on almost any soil, but to bring the fruit to perfection it must have culture and a rich soil. It is a heavy feeder and its greatest perfection is reached on heavily manured soil. It will even do without culture if the soil is made very rich and the whole surface between the rows is mulched. It is a cold-blooded plant and will thrive and bear perfect fruit when heavily mulched with sorghum bagasse, straw, or even coal ashes. Some growers mulch heavily near the plants and cultivate in the centre of the rows. Sawdust kept on the surface is often used near to and between the plants in the line of the rows. But in this case the old, partially rotted sawdust is used. The Fay currant is specially benefited by the sawdust mulching, as much of the fruit hangs down on pendent branches, which the mulching keeps clean.
It must be kept in mind that with currants the feeding-roots run very near the surface. Hence commercial growers cultivate with a narrow harrow, with the teeth slanted back, while the plants are young, and then mulch the whole surface. But others continue the shallow cultivation, with frequent manuring.
In field culture the principle of renewal is practised. The best fruit grows on two-year-old wood, and many growers of fancy fruit prune out all wood older than two years, and have young wood coming forward to fill its place. But the usual rule is to cut out all canes older than three years. This annual cutting out of old canes favors the starting of many new shoots. The superfluous ones must be cut out. But those coming from the older wood are not cut back closely. Spurs are left which load with fine fruit the next season.
In garden culture it is best to follow this renewal plan, as where the old wood is left the fruit soon becomes small and the currant-borer will rapidly increase in number and injury to the canes.
Some summer pinching should also be practised on the points of growth of the most vigorous shoots. This gives better form to the bush and also favors the development of fruit-spurs at the base of the shoots.
When the tree form is desired in private yards or gardens, a single shoot is started from the single bud left at the top of the cutting. The second spring cut the cane back to a height of from twelve to eighteen inches and allow four or five shoots to branch at the top. The third spring shorten the branches and allow ten to twelve shoots to grow. The after-pruning is a repetition of cutting back in such way as to secure new growth in symmetric form. But those who attempt this plan of training must keep in mind the necessity of short pruning. The spurs are cut to within an inch of the old wood early each spring.