Blackcurrants well suited to cool prairie nights.
During World War II, when oranges were effectively unavailable in England, blackcurrants were eaten for their vitamin C. Prior to that, they had been consumed to combat scurvy. And their use as a medicinal plant goes at least as far back as the Middle Ages. They’ve been a part of the prairie fruit garden since European settlement and Indigenous peoples had used wild currants for centuries previous to that.
Blackcurrants (Ribes nigrum), native to Europe and northern Asia, are thornless and vary in height from 3 to 6 feet. The roots are relatively shallow, 8 to 16 inches deep, and plant width depends on age, cultivar and pruning.
Some of the older cultivars are ‘Boskoop Giant’, ‘Kerry’, ‘Albol’ and ‘Walter Willoughby’. The latter has probably been the most widely grown because of its resistance to powdery mildew and relative drought tolerance.
Three newer hardy cultivars, all developed in Scotland, are contributing to a blackcurrant renaissance on the prairies. ‘Ben Nevis’ produces large firm berries of good flavour, has good frost tolerance, is productive and vigorous. ‘Ben Alder’ has high yields of medium small berries that are excellent for juicing, is resistant to mildew, and flowers late enough to escape frost damage. ‘Ben Sarek’ produces large firm berries in mid-season, has a semi-dwarf habit, is very productive and resistant to both powdery mildew and white pine blister rust. ‘Ben Connan’ (Scottish Crop Research Institute, 1994, ‘Ben Sarek’ x ‘Ben Lomond’) berries are easy to pick and considered enormous for a blackcurrant. The bushes are compact but upright.
Plants usually bloom by the last week in May. Fruit is borne on second and third year wood in late July. Almost all of the cultivars are selffertile: you only need one bush to produce fruit. Blackcurrants will have much better yields if more than one compatible variety is planted.
Currants are well adapted to our cool prairie nights. They do best in well-drained but moisture retentive soils (a clay loam is better than sand) with a neutral pH of 6 to 7.5. Incorporate generous amounts of organic matter (well rotted manure, peat moss or compost) into the soil. Space plants 3 to 5 feet apart to encourage air circulation and make picking easier. Start with one- or two-year old plants, cutting them back to a couple of buds (about six inches) at planting in the spring. This eliminates fruit for that season but encourages stronger plants to develop. Water well at the time of planting.
To eliminate weed competition, reduce the incidence of powdery mildew, maintain a cool root run, and provide the even moisture that black currants thrive on. Mulch and drip irrigation are recommended. Lay down the drip irrigation line immediately after planting. Cover the soil 3 feet to either side of the row with a 4-inch deep organic mulch layer (e.g. weed-free straw or hay, flax shives, post peelings).
After the second year of fruiting, remove the oldest branches at the base of the bush, leaving 6 to 8 twoand three-year old fruiting canes. This will open up the centre of the bush to allow light penetration and increase fruiting. Remove low and sagging branches which tend to root and become a nuisance. Eliminate seedlings that have developed from fallen fruit as they seldom come true to the parent plant. Follow up with a high phosphorous fertilizer application (e.g. 11-48-0 or 16-20-0).
Powdery mildew can be controlled with good spacing, resistant cultivars and the use of drip irrigation which leaves the foliage dry. Aphids sometimes suck the sap from the undersides of young leaves, distorting leaves and weakening plants. To control, apply a dormant oil spray (aka horticultural oil) in spring before the plants leaf out. Currant worms (smooth green caterpillars that eat the leaves) can be controlled with insecticidal soap.
Although the flavour of blackcurrants is said to be an acquired taste, I’ve found it an easy taste to “acquire”, especially in juice, syrup, jelly, topping and wine.
Sara is the author of numerous gardening books, among them the revised Creating the Prairie Xeriscape. And with Hugh Skinner: Gardening Naturally – A Chemical-free Handbook for the Prairies; Trees and Shrubs for the Prairies, and Groundcovers & Vines for the Prairies. Expect Fruit for Northern Gardens with Bob Bors in November, 2017.
This column is provided courtesy of the Saskatchewan Perennial Society (SPS; www.saskperennial.ca; hortscene@yahoo.com; www.facebook.com/saskperennial). Check out our Bulletin Board or Calendar for upcoming garden information sessions, workshops, tours and other events. Email gardenline@usask.ca with your questions or call Helen at 306-966-5865.