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.
Brown rot: Brown rot is a fungal disease causing a brown, spreading rot in fruit, sometimes with white pustules of fungi on the surface. It is usually worse in wet summers.
Remedy: Remove all rotten fruit as soon as you see it and destroy, this will prevent the spread of the rot. There is no chemical control.
More info on Brown rot
Silver leaf: Leaves develop a silvery sheen, cut branches reveal red staining.
Remedy: Prune from the end of June until the end of August or in early spring. Keep pruning cuts to a minimum, pruning regularly so cut surfaces are small.
More info 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 info on Plum maggots
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 info 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.
More info on Wasps
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.
‘Marjorie’s Seedling’ AGM: Heavy cropping, culinary plum.
‘Czar’ AGM: Blue plums for cooking.
‘Victoria’ AGM: Dual-purpose plum with orange-red fruit from late summer to early autumn.
‘Blue Tit’ AGM: Compact dessert plum with blue, juicy fruit in late summer.