Plums are one of the easiest fruits to grow as they require little pruning and often crop heavily. Self-pollinating varieties mean only one tree is needed, and there is a range of cooking and eating types to suit all tastes.
How to Grow
To give a good crop, plum trees need plenty of moisture and require a
moist soil that drains freely. They also prefer a sheltered site to
protect their early spring flowers from damaging frost. Bare root trees
should be planted in the winter; those grown in containers can be
planted at any time if kept well watered. Plum trees are too vigorous to
train as cordons or espaliers but can be grown freestanding, as fans,
or in containers if you choose trees grafted onto dwarfing rootstocks.
Plums are prone to a number of diseases that can kill trees if infected
growth isn’t pruned out quickly. Check trees regularly.
Plum trees are supplied grafted on rootstocks that restrict their size
and encourage regular harvests. Two rootstocks are commonly used:
- Pixy: Semi-dwarfing, suitable for trees in containers. Trees grow up to
7 feet (2.2 m).
- St Julien A: Semi-vigorous. Trees grow up to 9 feet (2.7 m).
Self-fertile plums pollinate their own flowers, so you only need to grow one tree. Others need separate pollinators that flower at the same time. When buying plums, choose those from the same pollination group, labeled A to C (early to late) according to flowering time.
Plums flower in early spring and are at risk of frost damage. Cover young and container-grown trees with garden fleece when frosts are predicted. Remove during the day to allow insects to pollinate. Young fruitlets are also vulnerable to frost.
Most plums are self-pollinating (SP), but some will need separate pollinators. Consider these varieties when choosing your plum tree:
- Plums: Try 'Avalon’ (dessert; pollination group A), ‘Blue Tit’ (cooking/dessert; SP), ‘Early Laxton’ (cooking/dessert; B), ‘Marjorie’s Seedling’ (cooking/dessert; SP), ‘Opal’ (cooking; SP) and ‘Victoria’ (cooking/dessert; SP) varieties.
- Gages have possibly the most delicious fruit within this group. They are usually sweeter and have a rounder shape than plums. Try Cambridge Gage’ (partly SP), ‘Denniston’s Superb’ (SP), ‘Golden
Transparent’ (SP) and ‘Old Green Gage’ (C) varieties.
- Damsons are smaller than plums and gages and tend to have a darker skin and sharper flavor, making them excellent for cooking. Try ’Farleigh Damson’ (C), ’Merryweather Damson’ (SP) and ‘Prune Damson’ (SP) varieties.
- Bullaces bear the smallest, most abundant fruit of all and are very hardy. They are only suitable for cooking due to their tart flavor. Try ‘Black Bullace’ (SP), ‘Langley Bullace’ (SP) and ‘White Bullace’ (SP) varieties.
Plums are ready to pick when slightly soft. They often at different times on the same tree, so several pickings may be required. Plums and gages are ready mid- to late summer, damsons and bullaces towards autumn. Pick fruit with the stalk still intact. Ripe plums don’t keep long, so eat them soon after picking. Firm and slightly underripe plums will ripen in the fruit bowl over a couple of weeks.
Pruning and Training
Plum trees should be pruned as little as possible to avoid silver leaf infecting the wounds. Only prune plums when in active growth in spring and summer. Keep these tips in mind when maintaining your plum trees:
- Prune new freestanding trees by removing the main stem above the uppermost sideshoots, and shorten three to four healthy branches by half or two-thirds to promote bushiness.
- To prune established trees, thin congested stems to improve airflow between branches, take out weak or damaged growth, and remove overly vigorous upright new shoots.
- Prune new fan-trained trees by removing the main stem and leave only two branches 16 inches (40 cm) long either side of the main stem, 10 inches (25 cm) above the soil. Train the two fan arms using canes fixed to wires.
- The first summer, select new sideshoots to train against the wires and tie in new growth. Cut back surplus shoots to one leaf, and any growing the wrong way or from below the fan arms. Repeat in following years.
Watch Out for These Pests and Diseases
Plum leaf-curling aphid suck sap from the leaves, causing them to curl and become misshapen. Treat with pesticides in midwinter and again at bud burst.
Silver leaf can also be a problem entering wounds and causing a grey sheen on the leaves that may turn brown and fall. As the disease spreads, branches die back, until the whole tree dies. Prune infected material but sterilize tools between plants; silver leaf is easily spread.