Mike & Katrine Juleff
Jostaberrynamed from the German –“(Schwartz) Johannisbeere – (black) currant and Stachelbeere” – gooseberry
Background and CharacteristicsA jostaberry is a generic cross between the blackcurrant (Ribes nigram) and the gooseberry (Ribes grossularia) and shows some characteristics of each. The jostaberry is thornless like a blackcurrant, with thick vigorous growth, largish budsand shoots that also resemble blackcurrant growth. The leaves are similar to gooseberry leaves though larger. The flowers of the jostaberry are small, about 8millimetres long, and a quite beautiful, flattened bell shape and have maroon petals that fold back in a very attractive fashion.
The flowers are tender and subject to frost damage from spring to mid-summer. The leaves of the jostaberry are not susceptible to gooseberry powdery mildew disease, which can kill most gooseberry cultivars. The plant is extremely vigorous and grows much lager than the gooseberry and blackcurrant plants. It is not unusual to see more than one metre growth during one season.
The roots of the jostaberry resemble blackberry roots and can be up to 10 millimetres thick. They also can spread widely, though there is no evidence of suckering. The fruit exhibits characteristics of both blackcurrants and gooseberries. Fruit are borne on strong stems, hanging in clusters of about 3-7 well spaced fruits. The fruit first develop into green fruit veining typical of gooseberry fruit. The fruit then turn pink /red as they mature, still with gooseberry characteristics. Finally they turn a deep opaque purple- black more like a blueberry The skin of the berries is quite tough at this stage, much more so than either gooseberries or blackcurrants. Largish berries of 10 millimetres diameter are not uncommon and the taste varies from a slight blackcurrant flavour to one of grapes. The longer the fruit are left on the plant the better, as this seems to increase the sugar content. The fruit tend to pull away skin if separated from the bunch as they are picked, so it is best to clip fully ripened bunches when harvesting.
BenefitsJostaberries are an excellent fruit to eat fresh or after they have been refrigerated. They also freeze well. Jostaberries add a delicious flavour to homemade ice cream and are excellent in pies, cakes and stewed. A wonderful jam can be made using fully ripened berries. Savoury uses are in chicken dishes and salads or for great chutneys and relishes.
Growing your own
Jostaberries can be grown in cool to temperate areas of Australia. They can be grown organically, as they seem free of disease in Australia and the only pest problem is birds.
Our plants, which are in a sandy soil with low acidity, are thriving. They receive pelletised organic fertiliser and compost in late winter and liquid seaweed drenches every so often. We also mulch the plants with layers of rotted hay to help keep the root area moist during summer.
Our resident frog population helps to control insect populations.
Pruning is usually done during winter when the jostaberry plant loses its leaves. Plants can be pruned to a vase shape, a single cordon or as a high standard, or left as sprawling bushes. Most flower buds form on branches that are at least one year old so it is important to not prune very hard as this will reduce potential cropping. When pruning plants to the espalier or cordon (single trunk) shape, the jostaberry shoots can be shortened in summer to produce bushy growth along the stems. A contact from the USA says they grow the jostaberry as a hedge and just attack it with a hedge trimmer but I feel it would need proper pruning every so often to remove really old wood.
The plants can be grown trained as espaliers against a wire mesh fence. The main branches are not pruned much at all; just remove those branches that are growing outside of the flattened plane of the espalier shape and do not prune any of the branches left on the bush. Branches form a loose open fan shape and these branches are tied back to parallel wire supports. The best espalier shape to use is the open palm like shape as the plants are strong and vigorous.
Propagation of Jostaberries is easy. Cuttings gathered during pruning can simply be stuck in potting mix and will root readily. Jostaberries also layer easily in good mulch.