Cover fan-trained trees temporarily in a tent of horticultural fleece on frosty nights when plants are in flower, holding the fleece away from the flowers with canes. Fruit set is generally finished by early summer, after which the fruits start to swell significantly.
Once fruit has set, they may need thinning to ease congestion and weight in the canopy, as well as to boost fruit size. It is often essential to prop up branches in mid- and late summer, as fruit weight can otherwise snap them.
Yields can be greatly increased by appropriate and timely feeding and watering. Because they can set such heavy crops, plums and gages, and to a lesser extent damsons, respond well to fertilisers, especially nitrogen.
On established trees apply a mulch of well-rotted farmyard manure in mid-spring to help retain soil moisture, keep down weeds, and provide nitrogen. This can be supplemented with a top-dressing of dried poultry pellets or non-organic nitrogen fertiliser such as sulphate of ammonia. Add a top-dressing of sulphate of potash in late winter.
Pruning should be carried out in spring or summer. Avoid pruning in the dormant season or in mid to late autumn, as there is risk of infection from silver leaf disease and bacterial canker.
There are three commonly used methods of plum pruning and training: bush, pyramid and fan.
Plums have quite high moisture demands, so they are best planted on good clay or loamy soils. But sites also need to be well drained as plums, and gages in particular, hate waterlogged soils. Add bulky organic matter to sandy or shallow chalky soils prior to planting. When growing in a container, make sure pots are large enough to prevent the potting compost drying out in summer.
These stone fruits are some of the earliest crops to flower in the fruit garden. While the plants themselves are often extremely hardy, the flowers can easily be killed by frosts, so it’s essential to position trees out of frost pockets or windy sites; a sheltered, sunny spot will produce the best results.
Gages in particular are best sited against a south- or west-facing wall to ensure the fruits are exposed to sufficient sunshine and warmth to develop their sweet, rich flavour and to ripen wood.
Thanks to modern rootstocks and restrictive training techniques any garden can accommodate at least one of these trees - if not more. Standard, pyramid, fan, and festooned tree forms are all possibilities.
There are hundreds of cultivars to choose from for both cooking and dessert use - those with limited outdoor space can opt for a dual-purpose cultivar to get maximum use from the crop.
Many are self-fertile so a single tree can be planted, while some are self-infertile, so check with the supplier before buying. When buying look for a system of well-balanced branches with a strong central leader. You can then train and prune the plant to any of the popular tree forms.
Plant plum trees during the dormant season, before growth starts in late winter or early spring. Bare-root plants usually establish better than container-grown trees. Stakes or training wires may be needed depending on the type of tree form you decide to grow.
Silver leaf: This fungal disease causes a silvering of the leaves followed by the death of the branch.
Remedy: The fungus produces most of its infectious spores in autumn and winter, so pruning in summer avoids problems. Not only are there fewer spores in this season, but pruning wounds, the main point of entry for the spores, heal more quickly.
More information on silver leaf
Plum maggots: The larvae of plum moth and plum sawfly tunnel through fruits making them unappetising. In the case of plum moth, misshapen fruits form and there are droppings within the fruits. Damaged fruitlets often fall in summer.
Remedy: For plum moth deltamethrin or lambda cyhalothrin can be used in mid June with a second application three weeks later. Pheromone traps, specifically for plum moth, are available and these can help get the timing of sprays right. These traps capture male moths and might actually help protect isolated trees. Plum sawfly is prevented by spraying at petal fall with the same materials. On small trees it is worthwhile looking for damaged fruitlets in May. These should be removed before the larvae complete their feeding and go into the soil.
More information on plum moth
Brown rot: A fungal disease that causes a brown, spreading rot in fruit.
Remedy: Prevent the disease overwintering by removing all brown rotted fruit promptly and composting. Do not allow rotted fruit to remain on the tree. Brown rot infects through wounds, especially those caused by birds, so if possible, net to reduce bird damage. Prune out and burn infected spurs and blossoms to reduce the amount of fungus available to infect fruit. The cultivars ‘Czar’, ‘Jefferson’, ‘Ontario’ and ‘President’ have some resistance.
More information on brown rot
Blossom wilt: This common disease, caused by the same fungus that causes brown rot, causes blossom to wither and rot soon after emerging.
Remedy: Minimise the carry-over of the fungus by removing all brown, rotted fruit promptly and composting. Do not allow rotted fruit to remain on the tree. Prune out and burn infected spurs and blossoms to reduce the amount of fungus available to infect fruit.
More information on blosssom wilt
Bacterial canker: This serious disease of stone fruit causes sunken, dead areas of bark often accompanied by a gummy ooze. It can kill off entire branches.
Remedy: Where possible, carry out all pruning in July or August when tissues are most resistant. This is also the best time to prune in order to minimise the risk of silver leaf disease. Cut out all cankered areas, pruning back to healthy wood and paint promptly with a wound paint to protect the wound from re-infection. Burn or landfill the prunings.
More information on bacterial canker
Wasps: All tree fruits are prone to wasp damage. As their fruits ripen, the high sugar content attracts wasps, which not only damages the fruit but also poses a threat to gardeners.
Remedy: Hang wasp traps in trees and harvest crops as soon as they ripen. Avoid leaving windfalls or over-ripe fruit on the ground.
Birds: Bullfinches in particular will eat fruit buds in late winter when their normal diet of seeds becomes scarce.
Remedy: Netting is the most reliable method of control, although not often practical for large trees. Try humming tape or reflective scarers as an alternative.
Aphids: Mealy plum aphid (white insects on the growing points and undersides of leaves) and plum leaf-curling aphid (curling young leaves) can appear in early spring.
Remedy: Either tolerate or spray with thiacloprid (not when trees are in flower).
More information on aphids
Plums develop their best flavour if left to ripen on the tree. If they feel soft when gently squeezed, they are ripe. Trees will generally need picking over several times.
Harvest fruits carefully so as not to bruise them, then eat fresh, destone and freeze, or make the fruits into preserves.
Nigel Slater says damsons are the best type for this ice cream recipe, but any rich-flavoured plums can be used.
Mary Berry offers this delicious chutney recipe for when plums are in season.
‘Early Laxton’ AGM - A dessert plum with red flushed, yellow fruit in mid to late summer.
‘Blue Tit’ AGM - Compact dessert plum with blue, juicy fruit in late summer.
‘Victoria’ AGM - Dual purpose plum with orange-red fruit from late summer to early autumn.
‘Czar’ AGM - Blue plums for cooking.
‘Marjorie’s Seedling’ AGM - Heavy cropping, culinary plum.
‘Farleigh Damson’ - Cooking damson produces regular, heavy crops with an excellent flavour. Partly self-fertile.
‘Prune Damson’, syn. ‘Shropshire Damson’ - A self-fertile culinary cultivar, with deep purple fruit with an excellent flavour.
‘Cambridge Gage’ - A compact, partly self-fertile gage with excellent flavour. Use both as a dessert and cooking variety.
‘Golden Transparent’ - The flavour of this dessert gage is sweet and excellent, and the yellow fruit is produced regularly and heavily. Self-fertile.