Currants, a staple in European gardens, remain something of an enigma to American growers. The fruits are something of a cross between grapes and berries. Red, white or black currants make relatively unfussy crops and can even be tucked into shady areas and still produce decent yields of their fruit, particularly in areas which experience hot summers.
Red and White Currants
Red and white currants are grown and pruned somewhat differently than black currants, and in fact are botanically closer to gooseberries than to black currants. Red currants make better dessert, wine and jelly fruits than they do fresh-eating fruits. (Fans of "Anne of Green Gables" will remember that the heroine unwittingly got her best friend drunk on red currant wine.) The "sport," or descendant, of red currants, the white currant, is suitable for both fresh eating and cooking. Both red and white currant shrubs grow about 5 feet tall and wide, live an average of 15 years and produce about 10 lbs. of fruit during each growing season.
Black currants taste best as desserts, jams or jellies rather than as "straight from the bush" fruits. Most shrub varieties produce between 10 and 15 lbs. of fruit each and live up to 15 years. They are larger shrubs than the other currant types. They are excellent for jellies, wines and a kind of paste that Europeans call "blackcurrant cheese," made by simmering equal parts fruit and sugar for one hour, straining the pulp, and reducing the juice until it reaches a thick consistency.
Choose a sloping site, if possible, and avoid planting the shrubs at the bottom of a hill, where cold air collects and poses the threat of frost damage. Plant currants in raised beds if the ground gets boggy during rainy spells.
Test the soil to ensure that the pH level falls somewhere between 5.5 and 7.0. If the soil is too acid, add lime in amounts recommended by your local extension service. In addition, add manure or other organic matter to the garden before setting the bushes in. The Oregon State University Extension Service suggests adding two or three bushels of manure for every 100 square feet. Keep the area weed-free.
Plant currants in early spring. Set red and white currants 3 to 4 feet apart and black currants 4 to 5 feet apart. Hedges--most common with black currants--should be spaced with about 2 ½ feet between shrubs. If planting currants in multiple rows, space the rows 8 to 10 feet apart.
The Oregon extension recommends setting the plants 2 inches deeper in the ground than they grew in their nursery pots. (If you receive the currants "bare root," look for the soil line and plant the shrubs 2 inches deeper than the soil line.) Prune all branches to about 6 inches long to stimulate growth.
Give currant plants a 4-inch layer of mulch. Keep the plants well-watered during drought periods and make sure the watering system moistens the soil to a depth of at least 6 inches. The plants begin producing a year after planting and reach heavy yields three to four years after planting. Continue adding organic fertilizer each spring, or about ¼ lb. of synthetic 10-10-10 per plant.
Black currant shrubs produce fruits on 1-year-old canes, so maintain a proportion of half canes from the previous year and half new shoots. Alternatively, cut the bushes completely to the ground during their dormancy period, and harvest every other year. For red and white currants, aim for one-third each of 1-, 2- and 3-year-old canes. Remove older canes.