Plum

Plum: how do you recognise it?

Habit

Fruit tree of 4–8 m with an open, somewhat irregular crown; as a bush, half-standard or standard.

Leaf

Alternate, elliptical, 4–10 cm, toothed and dull; somewhat hairy underneath.

Bark

Dark greyish-brown and cracked.

Flower

White flowers in small clusters in April, just before or with the leaves.

Fruit

Blue, purple, yellow or green plums with a flat stone (August–September).

Difference from blackthorn

Blackthorn is a thorny shrub with small blue sloes.

Difference from wild cherry

Wild cherry has shiny bark with horizontal bands, and cherries.

Flowering: April · Harvest and fruit: July–September · Pruning: June–August

Identify by feature: White blossom

Looks like it, but isn’t

• Blackthorn Prunus spinosa: a thorny shrub with small blue sloes. Difference from blackthorn
• Wild cherry Prunus avium: shiny bark with horizontal bands, and cherries. Difference from wild cherry

Why grow it?

• Your own plums from summer into September, fresh, in tarts or as jam.
• Many varieties are self-fertile: one tree is enough.
• Blossom in April for bees and bumblebees.
• Grows in almost any soil and needs little pruning.

Plum: where does it grow best?

• Sun: that is where plums are sweetest.
• Almost any fertile soil that holds moisture; no wet feet.
• Sheltered from cold winds: the blossom comes early and is sensitive to night frost.
• Space: 3–4 m for a bush or half-standard, 6–8 m for a standard.

Light

Full sun

Legal basis

Any garden soil

Moisture

Normal

Size

8 m tall, 5 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Nasturtium: Under the tree it lures aphids away and flowers all summer.
• Chives: A low edge under the crown that attracts bees.
• Crocus: In the grass under the tree: early flowers for the first bees.

Plum: when and how to plant it?

1. Plant from November to March; a container-grown tree can go in all year, except in frost or drought.
2. Choose the rootstock to suit your space: Pixy for a small tree, St Julien A for a bush or half-standard, a vigorous rootstock such as a cherry plum seedling for a standard.
3. Keep the graft union above the soil and put a sturdy stake on the windward side.
4. If you only have room for one tree, choose a self-fertile variety, such as ‘Victoria’, ‘Opal’ or ‘Oullins Gage’.

Care

Watering

In dry spells during the first year, and in dry summers while the plums are swelling.

Feeding

In March, some compost under the crown.

Thinning

If the tree is heavily laden, thin the young plums in June to 5–8 cm apart.

Propping branches

Heavily laden branches break easily: prop them up with a stake or tie them in.

Harvest

Pick in several rounds, when the plums are fully coloured and feel soft near the stalk.

Tip: On a heavy-cropping variety like ‘Victoria’, thin the fruit in June: the plums grow bigger and the branches don’t break under the weight.

Plum: when to prune it?

Pruning months: June–August.

When: In summer (June–August), in dry weather: young trees in June, cropping trees preferably just after harvest.

How:

• Prune lightly: thin out and remove crossing, inward-growing and dead branches.
• In the first years, train a young tree into an open crown with 3–4 main branches.
• Cut a branch back to a side branch or the trunk, without leaving a stub, and avoid large wounds.
• Remove branches with silver leaf or canker back to healthy wood.

Caution: Don’t prune in autumn or winter: hard pruning in winter risks silver leaf and bacterial canker. Disinfect your saw and secateurs.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Grafting

A variety is propagated by budding onto a rootstock in summer, or by grafting a scion in spring.

Sowing

A plum stone gives a new, unpredictable plum, not the same variety; sow it outdoors in autumn.

Plum: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Fully hardy; the early blossom in April can be frosted, though.
• In winter, remove shrivelled plums (mummies) from the tree, without pruning: brown rot overwinters in them.

Diseases and pests

• Silver leaf: Leaves with a silvery sheen, then branches die back; the wood is brown inside. Cut out affected branches in summer back to healthy wood.
• Bacterial canker: Sunken patches on the bark with oozing gum, and small holes in the leaves. Cut out affected branches in summer, in dry weather.
• Brown rot: Rotting plums with grey fungal pustules, and withered blossom. Remove rotten plums and mummies.
• Plum moth: A caterpillar in the plum; affected fruit colours too early and drops. Pick them up, and hang a pheromone trap in May.
• Aphids: Curled leaves at the shoot tips in spring. Ladybirds and earwigs usually clear them up.

Through the year

• January: Remove mummified plums; don’t prune.
• March: Compost under the crown; last month for planting.
• April: Blossom: watch out for night frost.
• May: Hang a pheromone trap against plum moth.
• June: Formative pruning of young trees in dry weather; thin the plums.
• July: Prune after harvesting early varieties; pick the first plums.
• August: Main harvest; summer pruning in dry weather.
• September: Pick late varieties; gather fallen plums.
• November: Planting.

What can you use it for?

Food and drink

Plums fresh, as jam, in tarts or dried.

For wildlife

Blossom for bees.

Edible and useful

Fruit (July–September)

Pick plums when they have their full colour, a light bloom and give a little when gently pressed; they will not get any sweeter after that. Damsons, mirabelles and greengages also belong to this species. Fresh, in tarts, as jam or purée, dried, or steeped in brandy.

Storing

Ripe plums keep for a few days in the fridge. Halved and stoned, they freeze well. Quetsche plums are also very good for drying (see recipe).

Caution: Do not crack or eat the stones: they contain substances that can release cyanide. Wasps love ripe plums: check each fruit before biting into it and take care when picking half-eaten fruit.

Eating and using is at your own risk: see the terms of use.

Recipes

• Plum jam (Jam · ± 4 jars · 45 min + 1 hour standing)
• Home-dried prunes (Dried · ± 300 g · 15 min + 12–24 hours drying)
• Plum and almond tart (Dish · makes 1 tart of 24 cm (8 portions) · 45 min + 30 min resting + 45 min baking)
• Plum liqueur (Liqueur · makes ± 1 litre · 20 min + 6–8 weeks infusing)

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Caterpillars

Host plant: caterpillars of butterflies or moths eat the leaves.

Did you know?

• Many plum varieties, such as Victoria, are self-fertile.
• Mirabelles and greengages are plums too: forms of the same species.
• The white bloom on a plum is a natural wax that protects the fruit from drying out.
• ‘Belle de Louvain’ is an old Belgian variety from Leuven: a large, purplish-red cooking plum.
• The plum probably arose as a cross between blackthorn and cherry plum (Prunus cerasifera).
• The greengage, called reine-claude in French and Dutch, is named after Queen Claude of France, wife of King Francis I.