Sour cherry

Family

Rosaceae

Habit

Tree

Height

6.5 m

Spread

6 m

Growth

medium

Lifespan

50 years

First yield

after 6 years

Hardiness

zone 3–9

Shade tolerance

light shade

Soil

Sand, Silt, Loam

Soil moisture

dry – moist

pH

6 – 7.5

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Edible: The fruits reach 15 to 20 millimetres, are light to blackish red and distinctly more acid than sweet cherries. The cultivar groups differ considerably: Amarelle and glass cherries have pale flesh and uncoloured juice and are mild enough to eat fresh, morellos and sweet morellos are darker and sweet-sour, and the Schattenmorelle is dark red and pronouncedly tart. Their real field is the kitchen: cakes, compote, jam, juice and kirsch. Besides malic and tartaric acid the fruits contain anthocyanins, rutin and chlorogenic acid, along with vitamins A, B, C and E, potassium and folate. The melatonin content of up to 13.5 nanograms per gram is notable, considerably higher in Montmorency than in Balaton.

Medicinal: Folk medicine has used sour cherries since antiquity for intestinal complaints, and dried fruit stalks are traditionally taken as a diuretic tea. In recent years research has focused above all on the juice: effects on uric acid levels in gout and hyperuricaemia, on inflammatory markers, on muscle soreness after exercise and — because of the comparatively high melatonin content — on sleep. No reliable therapeutic recommendations follow from this so far; the evidence is inconsistent and the quantities studied lie well above normal consumption.

Other uses: Besides the fruit, the sour cherry yields usable timber: reddish, medium-hard and fine-pored, though the slender trunks limit it to turnery, tool handles and small furniture parts. As an early and profuse flowering shrub it is a valued bee plant, with nectar sugar content between just under ten and fifteen percent. Seedlings and own-rooted stock serve as rootstocks in fruit growing. Its tendency to sucker makes the species suitable for informal hedges and for stabilising banks, where it forms colonies over time and creates cover. Branches cut in December and brought into the warm will break into flower indoors, a long-standing midwinter custom.

The sour cherry is less demanding and hardier than the sweet cherry, and is therefore the cherry for harsh sites. It wants full sun and a loose, fertile sandy loam; it tolerates neither waterlogging nor prolonged drought, since its water requirement exceeds that of the sweet cherry. Because it flowers only in April and May it escapes most late frosts. Almost all cultivars are self-fertile, so no second tree is needed. Cropping begins early and is regular. Pruning is decisive: the Schattenmorelle group fruits on one-year-old extension shoots and becomes bare from the inside without annual thinning; spent shoots are cut back to young wood after harvest. The main problem is Monilia blossom wilt, which must be cut back well into healthy wood.

Cultivars are always grafted, since seedlings do not come true. The usual method is budding in August at ten to twenty centimetres above ground, with whip grafting and cleft grafting as late-winter options. Rootstocks are wild cherry seedlings for vigorous trees, or dwarfing types such as Gisela or Weiroot for gardens, which give smaller crowns and earlier cropping. Some cultivars, above all the Schattenmorelle, can also be kept own-rooted: they produce abundant root suckers that can be lifted in winter and planted straight into their final position — the traditional cottage-garden route. Seed propagation is reserved for raising rootstocks; the stones need several months of cold-moist stratification over winter.

The sour cherry flowers in April and May and then supplies both nectar and pollen generously, with nectar sugar content between just under ten and fifteen percent. Around 46 wild bee species are recorded on it, including the early-flying European orchard bee, which favours stone-fruit blossom — though none of them are specialists. As larval food it matters less than native wild cherries, but moths such as the eyed hawk-moth and the figure of eight feed on its leaves. The greatest value lies in the fruit: blackbirds, starlings and thrushes strip a tree within days, an annoyance in an orchard and a benefit in a wildlife garden. As a shrub with abundant root suckers it forms dense colonies that provide cover and nest sites in hedges.

Notes: Flowers later than sweet cherry → little late-frost risk; self-fertile, no pollinator needed; Schattenmorelle fruits only on one-year wood → annual pruning essential; fruit of many cultivars does not detach dry → cut with the stalk rather than pull; melatonin and anthocyanin content well above sweet cherry; hardier and less demanding than sweet cherry, suitable for harsh sites;

Western Asia and south-eastern Europe, now cultivated throughout the temperate zone worldwide. The sour cherry is not a wild species but a cross between wild cherry and dwarf cherry that arose around the Caspian and Black Seas. No genuine wild populations are known; escaped trees are found in hedgerows and along woodland edges in many places. Cultivation extends to 63 degrees north in Finland and 68 degrees in Norway, and to 1,600 metres in the southern Alps and 1,800 metres in the central Alps. The largest producers are Russia and Turkey, and in the United States above all Michigan. In Germany the main areas are Rhineland-Palatinate, Baden-Württemberg and Saxony.

A crop plant without a natural habitat of its own, the sour cherry occurs in the Central European countryside mainly as an escape: in blackthorn and privet scrub, on vineyard walls and embankments, in open oak woodland and in traditional orchards. It prefers warm, rather dry summer sites with loose, nutrient- and base-rich sandy loams. It dislikes waterlogging, though it tolerates it better than the sweet cherry; its water and nitrogen requirements are higher. Because it grows as a shrub and forms colonies by root suckering, its place is in semi-open hedge and margin structures — where poor grassland meets the edge of woody vegetation.