Tips for Cultivating and Maintaining Red Currants

Red currants are resilient, rapidly growing shrubs that yield delicate, tangy red fruits from late June to mid-July, typically starting from their second year. Their upright form and appealing, maple-shaped foliage make red currants a wonderful enhancement to any garden. These plants are self-pollinating, so a single specimen is sufficient to bear fruit.

Light

Red currants thrive in full sunlight for a minimum of six hours daily. In hotter regions, they prefer full morning sun followed by some afternoon shade, as excessive sunlight can scorch their leaves.

Soil

The soil should possess excellent moisture retention while ensuring proper drainage and aeration. The best option is silt or clay loam enriched with a significant amount of organic material. Sandy soil tends to overheat during warm weather. To mitigate this, enhance the soil with organic matter and maintain moisture levels by applying a layer of mulch, about two to three inches thick.

The optimal pH level for soil is between 6.2 and 6.5; however, red currants can thrive in a broader pH spectrum, from neutral to slightly acidic.

Water

Mature plants require consistent watering until harvest time, at which point their growth ceases, and they only require extra water during prolonged dry spells. For their shallow root systems, deep drip irrigation is the most effective method.

Heat and Moisture Levels

Red currants can withstand cold winters, but their early spring flowering leaves them vulnerable to late frosts. They struggle to thrive in temperatures exceeding 85 degrees Fahrenheit.

The blend of a warm, moist environment and inadequate air flow renders them particularly vulnerable to powdery mildew.

Fertilizer

Red currants require a significant amount of nitrogen for optimal growth. In early spring, apply a complete fertilizer, using a quantity of one-quarter to one-third of a pound, in a circular area surrounding each plant. Additionally, enhance nitrogen levels by spreading composted manure around the base of the plants.

Pollination

Red currants can produce fruit on their own, but all varieties yield a greater harvest when cross-pollinated by insects.

Varieties of Red Currants

• ‘Red Lake’ is a well-known variety that produces large, tasty, and juicy berries. However, it is prone to mildew and is sensitive to late spring frosts.
• ‘Jonkheer van Tets’ is a Dutch cultivar known for its early flowering and abundant fruit production. It is vulnerable to late frosts but shows resistance to mildew.
• ‘Stanza’ is a bush that produces medium-sized fruits and has a dense growth pattern; it yields its harvest from mid to late season.
• Ribes rubrum ‘White Grape’, commonly known as white currant, matures in the middle of summer and has a sweeter flavor compared to red currants. The berries are a creamy white color, and it can be beneficial to train the plant against a wall or fence.
• ‘Rovada,’ favored by commercial cultivators, yields an abundant harvest of sizable berries. Although it shows strong resistance to powdery mildew, it is susceptible to cane blight.

Red Currants Compared to Black Currants

Red currants and black currants belong to distinct species within the same family of gooseberries. The black currant, known scientifically as Ribes nigrum, has a sweeter flavor compared to the more tangy red currants. Additionally, red currants bear fruit on older branches, whereas black currants yield berries on fresh growth. The flowers of black currant bushes are white, while those of red currants exhibit a yellowish hue.

Harvesting

Red currants acquire their vibrant hue as they mature. The longer they stay on the bush, the sweeter and more delicious they become, but be cautious not to delay too much, as animals are fond of these fruits as well. Due to the delicate and easily torn skin of the berries, it’s best to avoid picking them one by one to avoid a juicy spill. Instead, use bypass pruners or scissors to snip off the entire clusters at once.

Tips for Cultivating Red Currants in Containers

Red currant plants thrive even in confined areas such as containers. Choose pots that are 12 to 18 inches in both width and depth for planting currants. The roots of currants are not deep, so they are well-suited for this type of planting. These plants favor organic potting soil, a balanced fertilizer, and consistently moist conditions. Ensure that the pots have sufficient drainage holes.

Pruning

Red currants primarily yield berries from canes that are two to three years old, and pruning is done accordingly. The objective is to maintain eight canes of varying ages that are capable of producing fruit on the plant.

Trim the plants while they are dormant, ensuring the complete removal of any canes that are diseased, broken, or poorly shaped. In the first winter following planting, keep only the six to eight healthiest canes. In the second year, repeat this process with the new growth, retaining only four to five of the strongest shoots from the previous year. Continue this practice in the third year. By the end of year three, you should have three or four canes for each year of growth. Eliminate any old canes that are no longer producing fruit, as they can be easily recognized by their darker coloration.

If you accidentally cut off canes, there’s no need to be concerned; the plant will recover and produce numerous new shoots in the following year.

Cultivating Red Currant Plants

In late winter or early spring, just before the growth season begins, you can propagate red currants from a healthy existing plant using techniques such as tip layering or stem cuttings, resulting in a clone of the parent plant. Additionally, red currants can be cultivated from seeds.

Here’s a method for propagating through tip layering:

1. Insert the end of a cane into the ground and cover it with about an inch of soil, then hold it in place with a stone or a brick.
2. Within a year, or even earlier, it will establish roots, allowing you to detach it from the parent plant and replant it.

Here’s a method for propagating plants through stem cuttings:

1. Select a stem segment measuring between 9 to 11 inches from last year’s growth, cutting just above the point where it connects to the older wood. Make sure there is a bud or growth node at the upper end.
2. Retain three to four buds at the top, and if there are additional ones along the stem, carefully remove them with a sharp knife.
3. With the same knife, gently scrape the underside of the stem to eliminate the bark, revealing the green layer to promote root development.
4. Insert half of the stem into the center of a pot filled with moist, nutrient-rich, well-draining soil. Position the cutting in a cold frame or a sheltered area during winter, ensuring the temperature remains above freezing, and provide regular watering. By autumn, the cutting should have developed enough new growth to be planted in the ground, if you choose to do so.

Growing Red Currants from Seeds: A Step-by-Step Guide

Seeds can be planted in a sandy compost or peat moss, but they need a period of cold stratification or a cool environment prior to germination. In their natural habitat, seeds typically sprout in the spring. You might want to place the seeds in a bag with peat moss, store it in a cool location, and ensure it remains moist.

1. Create small openings in the bag to enable airflow while stratifying.
2. Store the bag in the refrigerator at a temperature above freezing for a period of three to four months. Exposure to temperatures below freezing may harm the seeds and hinder their ability to germinate.
3. Once the cold cycle is complete, sow the seeds in a mixture of sand, peat moss, or a soilless seed starting medium.
4. The seeds need to be softly pressed into the surface of the mixture, which should be lightly covered with a thin layer of the same mix.
5. Seeds germinate most effectively at temperatures ranging from 65 to 75 degrees Fahrenheit, provided they are in bright, indirect light. There is no requirement for artificial heating to facilitate the germination process.

Transplanting and Replanting

Transplant currants every three years following the harvest into a pot that is one size larger. Replace the soil and prune the roots to prevent the plants from becoming rootbound.

Overwintering

Red currants can withstand winter conditions, but those that bloom early may be vulnerable to damage from late frosts. To safeguard new spring leaves, buds, and blossoms, use a floating row cover to shield them from late frosts.

Frequent Insects and Plant Ailments

Red currants are frequently impacted by powdery mildew, currant aphids, and leaf spot, all of which can result in leaf damage and loss of foliage. Cane blight, a serious fungal infection, can cause canes to wilt and ultimately die. To effectively prevent powdery mildew, it is advisable to choose resistant cultivars. Additionally, ensuring proper pruning and adequate spacing between plants can help minimize the likelihood of powdery mildew.