Jostaberries were first cultivated at the beginning of the 20th century and have been continuously developed since then. The tree, which belongs to the gooseberry family, is extremely resistant to powdery mildew and otherwise offers little breeding ground for other fungal pathogens. The Josta is an addition bastard, created from the gooseberry and the black currant. The large berries are similar to blackcurrant fruits and ripen from mid-June to late July. Not all jostaberries ripen at the same time, which complicates the harvest and extends it over several weeks. Ribes × nidigrolaria, the Latin term for berry trees, is a very robust plant and can also be used as a decorative screen in your own garden.
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location and substrate
Fruit trees need a lot of direct sunlight for the fruit to ripen evenly and for the flavor to develop. The jostaberry is no exception here either, so choose a full sun to light, partially shaded location for the plant. The Josta prefers permeable and humus-rich soils. Enhance soil that is too dry or heavy with larger amounts of humus.
watering and fertilizing
Waterlogging is a factor that the Ribes × nidigrolaria can hardly cope with. Therefore, only water moderately and only increase the amount of water on particularly hot summer days. To prevent root rot, you can mix pebbles with the substrate. This facilitates the rapid drainage of excess liquid. Only water with lime-free water to avoid damaging the plant.
For a high-yield harvest, the jostaberry needs a good supply of nutrients. In October and March, compost is used as fertilizer, which is mixed under the soil. From flowering you should use a liquid fertilizer that has a high nitrogen content. Fertilize according to package directions to avoid overdosing.
plant
Jostaberries are considered to have higher yields than the parent varieties and are becoming increasingly popular in kitchen gardens. The planting time depends on the condition of the berry bushes. Leafless plants are transplanted outdoors before they sprout; the warm season is suitable for leafy plants. Josta can be planted in rows, but the berry bushes tend to grow sprawling and lush as they get older. You should therefore plan a minimum distance of about 1.50 meters between the individual plants.
Make it easier for the jostaberry to root and dig a planting hole about 40 centimeters deep. The root ball may protrude slightly from the ground, which makes watering more difficult but reduces the formation of unwanted shoots. It is filled with humus-rich substrate, which was previously mixed with small amounts of coarse pebbles. Create a “pouring edge” for easier watering. This is a slightly raised, circular zone of substrate with the shrub protruding from the center. Keep this area free of weeds and ground-covering plants so that the irrigation water can drain off quickly.
In the next two to three weeks immediately after planting, the berry bush should be watered regularly to accelerate the growth of the fine adhesive roots. As soon as new leaves and shoots form, you can reduce the amount of water and the watering rhythm.
tub planting
Jostaberries are conditionally suitable for keeping in tubs. The strong growth and roots make it difficult to find the right planter for the berry plant. The yield of the tasty berries is also noticeably lower with this type of planting. Treat the Josta to a location in full sun and make sure that the root ball does not dry out in summer. Potted plants are supplied with nutrients every 14 days with liquid fertilizer. To protect against frost, the planter should be completely wrapped in burlap or fleece. This is the only way to ensure that the sensitive root system is not damaged by frostbite in winter.
propagation
The still relatively young berry variety is propagated using sticks. Between October and March is the best time to cleanly cut off healthy one- to two-year-old jostaberry shoots. Shorten the logs to about 15 – 20 centimeters, whereby one of the ends should have an eye. From this, the first shoots develop after successful rooting.
Take several leafless shoots and place them next to each other at a distance of about 5 centimeters. The stick is buried vertically in the frost-free ground, only the top eye protrudes about two centimeters. Root formation takes several months. Do not dig up the young jostaberries until the following autumn and move the strongest plants to their final location. Cut back existing branches to about 4 – 7 branches in order to encourage the berry bushes to produce more strong shoots in spring.
For cuttings, the soil may be dry and low in nutrients. No nutrients can be absorbed before the roots form. For this reason, you should keep the soil moderately moist even on frost-free days, but never supply it with fertilizer. Alternatively, you can also fill planters outdoors with sandy substrate and root the cuttings there. Snails and weeds are less common here than with direct planting outdoors.
To cut
For a high-yield harvest, you should treat the jostaberry to an annual cut. The first pruning is done with the young berry bushes as soon as they are planted. Then, during the vegetation break, which is between October and March, a clearing and shape cut is made. Remove all shoots that are older than 3 years, these can be recognized by the darker color of the bark. The cut should be made as low as possible. About 5 – 7 shoots remain and are cut back again by 2/3.
The only exceptions when cutting are branches growing towards the middle as well as old and diseased parts of the plant. These can also be removed during flowering and encourage the Josta to form new, healthy shoots. Regularly sharpen pruning shears and saws, because smooth wound edges are closed more quickly by the plants and offer less surface for fungal pathogens to attack.
Never try to grow Josta as a standard. Because the plant tends to be strong, bushy and the weight of the fruit could not be borne by one trunk alone. If you make an annual cut, the berry bush will reach a circumference of up to 1.5 meters over the years.
hibernate
Jostaberries are very hardy and can withstand long-lasting double-digit minus temperatures. Just protect the sticks with a layer of compost and wrap Josta in tub planting with a special fleece. Also check the substrate on frost-free days and, if necessary, add a small amount of water.
Tips for cultivating the jostaberry
The hybrid plant is relatively undemanding and makes no special demands on the hobby gardener. However, you should not leave the plant to its own devices. Regular pruning and the additional supply of nutrients are important for a high-yield harvest. Josta is more difficult to pollinate than the parent plants, so cultivate several berry bushes side by side. A row of jostaberries planted after a few years will provide a distinctive privacy screen with tasty fruits.
pests
The addition bastard is extremely resistant to fungal pathogens, but pests are often found on the jostaberry.
gooseberry sawfly
Completely eaten leaves on the berry bush are a sure sign of the gooseberry sawfly. In the months of May to August, the larvae of this pest can be found in several generations on one plant. Once pupated, the animals hibernate in the ground in order to infest the Josta with a new generation of pests in the following year. As a preventive measure, you should regularly mulch the soil around berry bushes. However, as soon as you discover the first feeding damage to the jostaberry, you should take other steps:
- Place foil under the plant and shake off the caterpillars.
- Collect eggs and larvae by hand.
- Use insecticides against biting insects.
When using chemical agents, make sure that they also reach the inside of the plant. This is where the newly hatched larvae begin their destructive work.
aphids
Different types of aphids are often found on the berry bush. With their mouthparts, they suck and pierce directly into the leaves of the plants and consequently deprive them of the vital cell sap. Not only the joy of reproduction and the insatiable hunger of the aphids cause problems for the jostaberries. The excretion of the lice – the so-called honeydew – attracts ants and serves as a food source for the fungal pathogen “sooty mildew”. Therefore, not only fight the aphids, but also remove the ants with biological means. A decoction of nettles or field horsetails has proven effective against the little pests. Spray the affected plants completely with the liquid for several days.
Strawberry Blossom Picker
In the case of an infestation with Anthonomus rubi, the affected plants have withered inflorescences. However, the tiny weevils are rarely able to cause serious failures in the berry harvest, so control is not necessary. No effective insecticides against strawberry blossom weevils are available in specialist shops.
spider mites
Shiny silver sprinkles on the leaves of the Josta are among the symptoms caused by the spider mites. This pest attacks outdoor plants preferably in summer. Rely on the natural predators of the 8-legged insects, which include lacewing larvae and assassin bugs, for example. If the jostaberry is not growing too luxuriantly, you can wrap the entire and well-watered plant in transparent foil for a few days. Spider mites do not tolerate high humidity and die as a result of this measure.
leaf bug
The pungent-smelling pests are often found on fruit bushes, where they suck the sap from the leaves. Leaf bugs have few natural enemies, so collect the insects by hand or spray the affected plant areas regularly with paraffin oil. If the infestation has progressed too far, you should use chemical products from specialist retailers.
Conclusion
Jostaberries are undemanding and very resistant to many diseases. If you are not put off by the different harvest times of the berries, you will find a perennial and strong-growing plant in the Josta, whose tasty fruits can be processed well into jams and juices.
