Sour cherry

Mature sour cherries are fully hardy and need no protection. Protect young trees in their first two years with a trunk guard of jute or fleece and a mulch layer of leaves over the root zone; do not prune in winter, only after harvest in summer, because open wounds in the cold season are prone to fungi.

The most reliable method for sour cherries that come true to variety is grafting: in winter, cut dormant, one-year-old scions and store them cool and moist (e.g. in damp newspaper in the fridge). In spring, when the rootstock is well in sap (April to May), graft by bark grafting or whip-and-tongue grafting onto proven rootstocks such as Prunus mahaleb (mahaleb cherry, more drought-tolerant, weaker growth) or Prunus avium seedling (more vigorous, deep-rooting). Alternatively, bud in August to September: insert a dormant bud under the lifted bark of a young rootstock (diameter 5 to 15 mm). Seal all cuts immediately with grafting wax or budding tape.

Root suckers are the easiest vegetative method for bushy sour cherries on their own roots (e.g. morello-type cherries) and often the most obvious route for home gardeners. Plants on their own roots form rooted shoots from the root system around the trunk. In spring or autumn, cut all round a strong, already rooted sucker with the spade, lift it with as much root ball as possible and plant it at its new location. Important: this works only with mother plants on their own roots. A sucker from a grafted plant carries the characteristics of the rootstock, not of the variety. Keep the young offset evenly moist in the first year.

For cuttings, take semi-ripe young shoots of one-year-old, already fruiting trees in the first half of June. Timing is crucial; later batches root much worse. Cut cuttings about 10 cm long, with the basal cut directly under a bud. Lightly score the base at the side to encourage root formation. Insert them into a free-draining substrate (e.g. a sand and perlite mix) and keep them evenly moist at soil temperatures of around 18 to 20 °C. Bottom heat or a heated propagation bed noticeably improves success. Prunus species are generally considered hard to root; expect uneven results.

Layering works with branches growing close to the ground: in spring, bend a strong young shoot down to the soil, lightly wound it at the bend, fix it with a stone or hook and cover this spot with soil. After one growing season, once the layer has formed roots, separate it from the mother plant.

Sowing is suitable only for raising rootstocks or for experiments: do not expect fruit true to variety, as sour cherries split strongly when grown from seed. Stratify the stones cold and moist for 8 to 12 weeks (fridge, damp sand) and sow in spring.