Currants

Growing currants in South Africa

Currant plants are mostly grown in the northern hemisphere, but also grows well at higher altitudes and cooler parts of SA. It can tolerate heavy frosts and winter temperatures of around -35’C.

Description

Currant (Ribes) is a thorn less shrub that grows well in cooler parts of the country. Currant bushes can grow up to 1.8m wide and tall. All currants have attractive flowers and maple like leaves that make them desirable in the edible landscape. It is a perennial crop that can tolerate moist areas.

Currants come in multiple species under the genus Ribes. They are sweet and sour flavourful fruits and mainly come in the following varieties (typically classified by their colours). Black, Red, Pink and White currants. The European Black Currant (Ribes Nigrum) has a strong and unusual flavour which bears a pendulous chain of small to medium size berries. Each currant berry has a size of about 1 cm in diameter, almost black with a glossy skin and a persistent calyx at its apex. It can carry about 3-10 tiny, edible seeds.

The Red, Pink and White currants are the same species (Ribes Sativum). The Pink and White currants are generally sweeter.

Black Currants

Black currants (Ribes nigrum) are known for their strong flavour that makes them perfect for syrups, jellies and similar food products rather than eating fresh.

Red Currants

These are typically used for making juices, jellies, purees and more.

White Currants

These have 3 species, R. rubrum, R. petraenum and R. vulgare and typically have lower acid content than other varieties, so they are good to eat fresh.

Pink Currants

Ribes vulgare or pink currant is an intermediate between white and red currants. It has colourless skin and pink flesh.

Nutrient Composition

Berries of red, white and pink currants feature translucent pulp, sweeter in taste. They, however, consider inferior to blackcurrants regarding antioxidant power.

Blackcurrants carry significantly high amounts of phenolic flavonoid phytochemicals called anthocyanin. Scientific studies suggest that consumption of currants can have potential health effects against cancer, aging, inflammation, and neurological diseases.
Blackcurrants have antioxidant value (Oxygen radical absorbance capacity- ORAC) of 7,950 Trolox Equivalents per 100g,which is one of the highest value for fruits after aronia, elderberry, black raspberries and cranberries. Red currants, however, possess comparatively less ORAC value of 3,387 TE.
They are excellent sources of antioxidant vitamin, vitamin-C.100 g of fresh currants provide more than 300% of daily-recommended intake values of vitamin-C. Research studies have shown that consumption of fruits rich in vitamin-C helps the human body develop immunity against infectious agents and also help scavenge harmful oxygen-free radicals from the body.
Black currants carry a small but significant amount of vitamin-A,and flavonoid antioxidants such as β -carotene, zeaxanthin, and cryptoxanthin 100 g fresh berries provide 230 IU of vitamin-A. These compounds are known to have antioxidant properties. Vitamin-A also required for maintaining the integrity of mucosa and skin, and essential for healthy vision. Furthermore, consumption of natural fruits rich in flavonoid antioxidants helps to protect from lung and oral cavity cancers.
Fresh blackcurrants are also rich in many essential vitamins such as pantothenic acid (vitamin B5), pyridoxine (vitamin B-6) and thiamine (vitamin B-1). These vitamins are essential in the sense that human body requires them from external sources to replenish and required for metabolism.
They also carry right amounts of mineral iron. 100 g currant berries provide about 20% of daily recommended levels. Iron is an essential co-factor for cytochrome oxidase guided cellular metabolism and red blood cell (RBC) production in the bone marrow.
Additionally, the berries are also a very good source of other important minerals like copper, calcium, phosphorus, manganese, magnesium, and potassium, which are essential for body metabolism.

Currant uses:

Apart from eating fresh, currants make excellent juices, syrups and preserves. They can also be used to make cordials, wine, craft beers and other processed products such as freeze dried powders.

As previously mentioned, currants come in red, pink, white and black. Reds and pinks are used primarily in jams and jellies because they are quite tart. Whites are the sweetest and can be eaten fresh. Dried currants are becoming increasingly popular as a snack. Some currant shrubs are attractive enough to plant in a shrub or flower border. Frozen currants can be added to drinks such as iced tea, lemonade or cocktails.

Soil pH Levels:

It prefers a soil ph level between 5.5 to 7.0

Pollination:

Currant plants are self-fertile so cross pollination is not required for fruit development.

Site selection and preparation:

A good quality of blackcurrant is that it can withstand poor drainage more than other similarly soft fruits like it; however, for optimum growth, it should be planted in well-drained soil where there should be ample organic matter added and also there should be protection from very strong winds in areas such as in some Eastern Cape and Western Cape areas. A natural windbreak can be made by planting elderberry plants 1.5m apart in a row on wind facing borders. The elderberry plant can grow 2m high in one year and can reach up to 6m high in some soils which will not only provide an abundance of elderberries and a natural habitat for birds but also a good wind shield for a more wind sensitive currant orchard.

Currants grow well in sun or partial shade, and appreciate afternoon shade in very warm climates.

A mixture of 5% to 10% well-aged manures can be mixed in with compost and the soil that were dug out of the planting whole and placed back in the hole where the plant can be planted in. In the end, amply water the planting hole as even soaking will help firm the soil around the roots of the plant.

Plant Spacing and planting

Plant currant plants 1.5m apart in the rows and 2.2m to 2.5m between the rows.

There is a slight difference even in planting red and white currants from that of blackcurrants. While the blackcurrant is planted 5cm deeper than it was originally in the nursery, red, pink and white currants are planted at the same level. The reason for this difference is that in case of blackcurrant plant, it is desired to have more shoots emerging from the base of the plant whereas in case of red, pink and white currant plants, it is best to have a single stem having an open shape of bush on top.

Water thoroughly after planting and apply 5cm to 10cm of organic mulch around the plants. Mulch helps keep the soil moist and cool and prevents competition from weeds. Add additional mulch every year to bring it up to the proper depth.

Red, pink and white currants can be grown even as single (0.5m spacing), double (1.0m spacing) or triple (1.3m spacing) in a cordon configuration. This is the most common method as it is also the simplest method and which provides the highest yields.

Red, pink and white currants are less tolerant to shade and water logging and hence should be planted in full sun in a well-drained ground. These will also require protection from heavy frost in the very cold parts of the country for example such as some parts in the Northern Cape or Eastern Free State in South Africa. Plants can be protected with fleece cloth.

Interesting Facts:

From 1942 onward, blackcurrant syrup was distributed free of charge to children under the age of two. This may have given rise to the lasting popularity of blackcurrant as a flavoring in Britain.

Fertilisation

Results from a soil test are the most accurate guide to fertilizer and lime requirements. It is important to determine soil fertility and pH levels before planting, so that necessary agricultural lime and fertilizer can be applied to the soil.

Fertilization greatly depends on many factors such as soil fertility, soil structure, composition and climate so it is advisable to have the soil tested before starting with a production system. Adding organic matter to soils will improve the soil’s fertility, help reduce soil compaction of clay soil, improves aeration and assist with the moisture holding capacity.

Organic materials such as compost and/or well-aged manures can be worked into the soil in late winter before planting.

A little more fertilizer is needed for black currants than red, pink and white currants. Fertilizers should be added while preparing the soil for planting the young plants and also for established plants, during late winter.

Depending on the soil type, acidity, drainage and amount of rainfall, one has to add compost/humus, aged manure and a balanced NPK fertilizer, preferably with gradual release of nutrients.

Excessive doses of nitrogen can promote strong growth of plants, but the plants are weak and prone to physical damage and diseases. Fertilizers with potassium chloride (or other chlorides) should be avoided as it would be harmful to the biological life of the soil which is an essential part required to grow healthy and good yielding plants.

Irrigation

They need watering for maximum fruit production. Once the plants are established water them as needed usually once or twice per week when dry. Recent annual rainfall amounts need to be taken into account before planting. Currants require approximately 20mm of rainfall per week during the growing season. Drip irrigation is best as it not only maximises water usage but also provides water directly to the roots instead of on the canopy of the plants which can cause fungi and disease problems.

Pruning & Trellising

Pruning currant bushes is necessary to promote growth, train the branches, facilitate harvesting, remove any diseased material and most of all, to keep the plant’s interior open for optimum sunlight penetration which will lead to optimum yields. Currant pruning is a quick annual process and part of the regular maintenance program. It is important to note that the pruning style of blackcurrants differs from the red, pink and white currants.

Below are some basic tips for pruning currants. Detailed instructions with illustrations on pruning follow below this section.

Proper pruning will improve sun penetration into the plant and maintain good air circulation to minimize disease.
During the first three years of growth, allow four or five canes to develop per year.
A mature shrub should have 8 to 12 canes once pruning is completed.
Fruit is produced on one, two and three-year-old wood. For optimum yields, try to keep three to four canes of each age.
Always remove unwanted canes as close to the ground or main stem as possible.
The main pruning is best done in early winter retaining strong new shoots that arise from the base of your bush. If there are plenty new shoots, cut out most of the old wood which has fruited, otherwise remove a third of these old branches, pruning to a strong young shoot near the base of the bush. In this way, the bush will be completely ‘replaced’ every three years or so.
As an aid to pruning the youngest wood will be mid-brown in colour with the oldest wood becoming almost black after a couple of years.
The crown should be pruned to remove overlapping branches and long branches should be cut to encourage the development of lateral shoots.
Red, white and pink currants fruit mostly on spurs (short branches) of one, two and three-year-old canes.
The best way in how to prune currants is by using sharp implements that will make clean cuts and won’t invite pathogens. There are also various sterilisation products on the market which can be used to clean implements to make sure that pathogens are not being transferred.

Pruning Black Currants – Read more

With blackcurrants the fruit is carried on the previous year’s or older wood. For this reason, it is important not to over-prune or all the fruiting wood will be removed. However, it will be necessary to prune out older wood.

After planting, completely cut out any weak wood and reduce the other shoots to about 5cm or so above ground-level as indicated by the red cut markings in the image above. Each shoot should then only have two to four vegetative buds (where new shoots will sprout or already sprouted). Try to cut the shoot just above (about 5mm) from a healthy and outward-facing vegetative bud which will enable new shoots to grow outwards. This is because the first new shoot usually emerges from the bud closest to your cut and grows in the same direction as that of the bud. The bushes will then produce vigorous new growth that will provide a good crop in the second summer after planting. After this initial pruning, mulch with a layer of compost, manure or other organic material.

The following summer, growth will spring from these reduced shoots, as well as completely new growth from the base. Cut out any weak shoots as indicated by the red cut markings in the image above.

Cut out one-third of the old wood and any weak or damaged shoots right down to the base as indicated by the red cut markings in the image above.

Once established, cut out up to four of the oldest branches each winter and then cut back the remaining fruited branches to a strong shoot. Blackcurrants produce most on one-year-old (overwintered) growth, therefore the objective is to retain strong one-year-old canes as well as two-and three-year-old canes which have one-year-old shoots. All four-year-old canes are cut off close to the base as indicated by the red cut markings in the image above.

Pruning Red, Pink and White Currants – Read more

Red currants are different to blackcurrants because they are spur-fruiting and so a permanent framework has to be built up. Red, pink and white currants are pruned to a goblet (bowl) shape in both late winter and summer. In order to get a goblet shape bush, prune out some of the stems developing inside the bush and also any lateral branches heading towards the center.

Plant a new bush. Select four well-placed branches and remove the rest. Reduce the remaining branches to half their length, usually around 15cm to 20cm. Remove the lowest branches, weakest branches and any that are diseased, damaged or less than 15cm long. Any suckers from the soil at the base of the plant should also be pruned out. Suckers are new stems emerging from the base of the root ball or main stem. Refer to the image above.

In the second winter, prune back the new growth on all the leaders by about half, cutting back to an outward-facing bud as indicated by the red cut markings in the image above.

Once established, each winter cut back the tips of all the leaders and cut back any side shoots to one or two buds as indicated by the red cut marking in the image above. Leave three or four of each one-, two-, and three-year-old canes leaving basically 8 -12 canes per mature bush.

Cut back all current season’s growth by 2.5cm and remove congested old wood from the bush’s centre. Every midsummer after harvesting, cut back laterals to three to five leaves.

Pests and diseases

Insect pests are a minor concern for home growers of currants. Infestations are uncommon and rarely cause major damage. Possible insect pests include aphids, cane borers, spider mites, fruit worm, fruit flies, coleoptera (beetle families) and birds. Careful site selection and good cultural practices such as mulching, pruning and sanitation will minimize pest problems.

Currant Rust: This is a fungus that occurs in summer in the form of yellow spots turning red-orange. These are actually the fungal spores. Plant is weakened due to this disease and leaf malformation takes place. Apply a registered fungicide such as BASF Bellis (containing Boscalid and Paraclostrobin) which is registered in SA to be used on most berry crops including currants. Apply as soon as initial symptoms are seen. An example can be seen in the image below.

Currant Anthracnose: Brown spots appear on leaves in this disease. They spread fast and cover entire plant upon which leaves fall and plant dies. It occurs usually in hot and dry weather. A suitable registered fungicide such as BASF Bellis should be used immediately. An example can be seen in the image below.

Powdery Mildew: As the name suggests it takes place in the form of a powdery patina on leaves and is actually a fungus and can be a problem in some locations. It causes deformation of buds, twisting of leaves and elimination of flowering. Because of this, the plant is weakened and ultimately dies. To avoid this disease, spray plants with a registered fungicide such as BASF Bellis. Try to avoid overhead watering. Also affected parts should be cut and disposed of so as to avoid spread of the disease to healthy plants. Prevention is the best measure for controlling powdery mildew. Site plants where they will receive good air circulation and plenty of sunlight as this will reduce spore germination. Regular pruning improves air circulation. Remove any dead plant debris from the vicinity of currant shrubs as this material can harbour fungal spores. Remove affected plant parts at the first sign of powdery mildew to prevent spread to the rest of the plant. Dispose of plant debris in a hot compost pile or in the trash.

Harvesting

Plant life span: 12 years+

Years to start fruiting: 2-3 years

Years to mature plants: 4-5 years

There is no simpler way to tell when currants are ripe than to monitor the color and flavor of the fruits as they develop.

Pick blackcurrants only when they are properly ripe which is approximately one to two weeks after they turn black. The currants at the top of each cluster generally ripen first. Pick red and white currants as soon as they are ripe. Simply cut off the entire cluster with scissors.

All types of currants freeze well.

When using the fruit for jam, you should harvest it before it is fully ripe so that natural fruit pectin levels will be higher.

Currants have a shelve life of 10 to 14 days if stored between 2˚C and 6˚C

Commercial growing – yields

Yields between 5kg and 7kg per mature blackcurrant plant can be expected with the red and white currants yielding 4kg to 5kg per plant.

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