During the first growing season, keep new plants well-watered with one to two inches of water per week if rainfall is insufficient.
Red Currant Care
Established shrubs do not require much maintenance; they are tough and forgiving but be careful not to damage the shallow roots when weeding.
Light
Red currants need full sun at least for half of the day. In warmer climates, they do best with full sun in the morning and partial shade in the afternoon, as intense sunlight can burn the leaves.
Soil
The soil must have good water-holding capacity and at the same time should be well-drained with good aeration. Silt or clay loam with a high amount of organic matter is ideal. Sandy soil heats up too much in hot weather. To counter this, amend the soil with organic matter and keep it moist with two to three inches of mulch. The ideal soil pH range is 6.2 to 6.5 but red currants can be grown in a wider neutral to acidic pH range.
Water
Established plants only need regular watering up to the point of harvest, after which their active growth stops and they only need additional water during periods of extended drought. Deep drip irrigation works best for their shallow roots.
Temperature and Humidity
Red currants are winter-hardy, however, their bloom in the early spring makes them susceptible to late frosts. They don’t do well in temperatures above 85 degrees Fahrenheit. The combination of a warm, humid climate with poor air circulation makes them especially susceptible to powdery mildew.
Fertilizer
Red currants are heavy nitrogen feeders. Fertilize the plants in the early spring with one quarter to one third pound complete fertilizer in a circle around each plant. Also give the plants an extra nitrogen boost by scattering composted manure around the plants.
Types of Red Currants
‘Red Lake’ is a popular cultivar with large, flavorful, juicy berries. It is susceptible to mildew and does not tolerate late spring frosts.‘Rovada’, the preferred cultivar of commercial growers, is a heavy producer with large berries. While it is highly resistant to powdery mildew, it is prone to cane blight.
Harvesting
Red currants turn red when ripe. The longer the berries remain on the plant, the sweeter and more flavorful the berries (don’t wait too long though, as wildlife love the berries too). Because the skin of the berries is very tender and rips easily, to prevent a juicy mess, don’t harvest individual berries. Instead, cut off the whole berry clusters at once with bypass pruners or scissors.
Pruning
Red currants produce most berries on two- and three-year-old canes and pruning follows that pattern. The goal is to have about eight fruit-producing canes of different ages on the plant. Prune during dormancy and always remove all diseased, broken, or misshaped canes. In the first winter after planting, remove all except for six to eight of the strongest canes. In the second year, do the same with the new growth and also remove all but four to five of the strongest shoots from year one. Repeat this in year three. By the end of the third year, you will have three or four canes for each year of the plant. Remove all old canes that do not bear fruit any longer. They are easy to identify by their dark color. If you remove canes in error, don’t worry, the plant will bounce back with plenty of new shoots the next year.
Propagating Red Currant Plants
You can propagate red currants from an existing healthy plant by tip layering, which will produce the same plant as the parent. Place the tip of a cane in the soil and cover it with an inch of soil, then secure it with a rock or a brick. In a year, sometimes sooner, it will develop roots and you can separate it from the mother plant and transplant it.
Common Pests & Plant Diseases
Red currants are most commonly affected by powdery mildew, currant aphids, and leaf spot, which cause leaf damage and defoliation. Cane blight is a severe fungus that leads to the wilting and death of canes. The best way to prevent powdery mildew is to plant resistant varieties. Proper pruning and spacing between plants also reduces the risk of powdery mildew.
