Plum

Family

Rosaceae

Habit

Tree

Height

11 m

Spread

10 m

Growth

medium

Lifespan

120 years

First yield

after 5 years

Yield per plant

up to 60 kg a year

Yield in cultivation

up to 12 t/ha

Energy yield

550 kcal per m² a year

Hardiness

zone 5–9

Shade tolerance

partial shade

Soil

Sand, Silt, Loam, Clay

Soil moisture

semi-dry – very moist

pH

6 – 7.5

Synonyms

Pflaumenbaum

Planned in gardens

4×

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

Edible: Plums and damsons are eaten raw, made into purée, jam and cake toppings, dried, or fermented into spirit and liqueur; thanks to their firm, freestone flesh damsons are the classic baking and drying fruit, while juicy round plums are better fresh. Drying raises the sugar content sharply, and dried plums keep well. The flowers can be scattered over salads as an edible garnish, and an edible gum exudes from wounds in the trunk. The seeds inside the stone contain around twenty per cent oil; sweet-kernelled types taste of almond, whereas bitter-tasting kernels contain amygdalin, which releases hydrogen cyanide on chewing, and do not belong on the plate. Yield estimates run to some twelve tonnes per hectare, equivalent to about 552 kilocalories per square metre.

Medicinal: Dried plums act as a mild laxative; the effect comes from their high sorbitol and fibre content rather than any single active compound. It is well documented and the only reliable medicinal use of the species. An infusion of the bark as a fever remedy is recorded in folk medicine but has not been clinically tested. The seeds inside the stone contain amygdalin; bitter-tasting kernels release hydrogen cyanide on chewing and are not a food. For raw apricot kernels, chemically comparable, the EU sets a maximum of 20 milligrams of hydrogen cyanide per kilogram — a useful yardstick for plum kernels too. Leaves and bark also contain cyanogenic glycosides and do not belong in teas.

Other uses: Dyeing: Leaves are colored green, fruits are tinted gray-green, and the bark is dyed yellow. Resin acts as a glue. The seeds have oil. The wood is tough, dense, fragile, and challenging to dry, shrinking significantly and prone to cracking. Ideal for woodturning.

Plums thrive in well-drained, moisture-retaining soil and prefer a sheltered location. They do well in partial shade but bear more fruit in sunny spots, especially in loamy soil with some lime content. The pH of the soil should range between 6 and 6.5. Cultivated widely in temperate regions for their edible fruits, plums come in various varieties that yield fresh fruit from late July to November or December. While most types are self-fertile, some need cross-pollination, and a few are partially self-sterile. In limited spaces or challenging climates, plums can be grown against walls, with sunny south- or west-facing walls being ideal for most varieties. Believed to be a hybrid of P. spinosa and P. cerasifera with chromosome doubling, plums do not cross with Japanese plums, P. salicina. Plums thrive in a continental climate, with mild winters leading to earlier flowering but posing a risk of frost damage to blossoms. The best fruiting occurs away from the western side of the region. Plum trees generally have shallow roots and tend to form runners if the roots are harmed. Plants in this genus are highly vulnerable to the honey fungus.

Plum cultivars are grafted, since seedlings do not come true. The usual method is budding in August at ten to twenty centimetres above ground, with whip and cleft grafting as late-winter options. The rootstock determines vigour, soil tolerance and suckering: St. Julien A suits light soils and unirrigated plantings, WaVit and WeiWa good sites; all three produce almost no root suckers, which was the failing of older stocks such as 655/2. For restrained growth in gardens, Pixy is appropriate. One speciality is own-rooted propagation: the German prune and some landraces sucker freely, and these suckers can be lifted in winter and planted straight out — the traditional route in old orchards. Sowing serves only to raise rootstocks; the stones need cold-moist stratification over winter.

Plum blossom opens early in the year and ranks among the richest food sources of the season, offering abundant nectar and pollen at a time when little else is in flower. Around 46 wild bee species have been recorded at the flowers, most of them mining bees of the genus Andrena, and the bloom falls into the critical build-up phase of young bumblebee and honeybee colonies. Some 65 moth and butterfly species use plum as a larval food plant, five of them closely tied to it, including the black hairstreak. Several beetle species feed on wood, bark or blossom. Ripe and windfall fruit is taken by thrushes, starlings, finches and corvids, while older limbs give cavity-nesting birds a foothold.

Special features: hybrid [cherry plum (P. cerasifera) x blackthorn (P. spinosa)]; subspecies: German prune/quetsche(subsp. domestica), damson and bullace(insititia), half-damson(intermedia), gage(italica), spilling(pomariorum), ziparte(prisca), mirabelle(syriaca); flowers later than cherry plum+apricot+peach → less late-frost damage; no wild stands (pure cultivated hybrid); propagation: grafting(St. Julien A, WaVit, WeiWa, Pixy) + root suckers(own-rooted in Hauszwetschge);

Western Asia and the Caucasus, now grown throughout the temperate zone. The plum is not a wild species but a natural hybrid of blackthorn and cherry plum that probably arose between the Caucasus and the Caspian Sea; more recent work attributes the main share to various ploidy levels of the cherry plum. By way of the Near East — Damascus gave the damson its name — it reached the Mediterranean and came to Central Europe with the Romans. It occurs naturalised in hedges and along waysides, but genuine wild populations do not exist. The largest producer today is China with a good half of the world harvest, followed by Romania, Serbia, Chile and Turkey; in Germany around 71 per cent comes from Baden-Württemberg and Rhineland-Palatinate.

The plum is a cultivated hybrid without natural wild stands; its habitat is the farmed landscape. Traditionally it grows in orchard meadows, cottage gardens and hedgerows, and it also escapes onto field margins, waysides, railway embankments and open scrub, where root suckers often build dense groups. It needs a medium-heavy, humus-rich, nutrient-rich and well-aerated soil that stays fresh but never waterlogged; compacted ground troubles it as much as shallow dry soils. Sunny to partly shaded, warm positions suit it best. Because it flowers later than cherry plum, apricot and peach, its blossom is caught by late frosts less often — which makes it worth growing in rougher districts and higher valley sites as well.