Plums
Introduction
Plums can be gorgeous and rich with a soft, juicy, and sweet flesh. There are also more tart varieties of plums, and sometimes plums taste sharp simply because they have not ripened fully before being eaten.
Plums belong to the rose family, that also contains cherries, peaches, and apricots. From this family, plums and cherries standout as being easier to grow in the relatively cool UK climate. With the right plum tree, a gardener can be rewarded with a prolific plum harvest for many years.
Planting
- Planting depth: cover root ball
- Planting spacing: depends on root stock
Harvesting
- Enjoy fresh
- Make delicious jam
- Fresh plums do not store well
(inside)
(outside)
(fresh)
(stored)
= jar, = freeze, 
= store
Varieties
There are numerous types of plums including mirabelle (cherry), Japanese, and bullaces, but this section concentrates on the most common types of plum grown in the UK, namely: commons plums, gages, and damsons. In addition, there is a further bias towards dessert plums for eating fresh from the tree, rather that tart plums used for cooking.
Commonly grown plums can be divided as follows:
Common Plums
These are the largest type of plums and are most commonly purple, but can be yellow, or variegated shades of the two colours. Plums can be culinary (acidic like cooking apples) or dessert types, and the dessert types (when fully ripe) can be deliciously sweet. Typically, plums do not store or freeze well.
Gages
Like plums, the majority of gage varieties grown at home are sweet, but they differ in shape, being smaller and rounder than plums. Most often, gages are yellow or green.
Damsons
The hardiest variety of all, damsons are able to fruit reliably even when there are late frosts. Damsons are round or oval, small, blue or black, and have a tart flavour. Their acidic nature means damsons are most often cooked to make jams, compotes, and other sugary desserts.
There are many types of self fertile plum trees, which avoids the complication of finding a compatible pollinating partner. However, having another variety in the same pollinating group nearby can increase harvest size. There are partly self fertile plum varieties that are less reliable or give smaller harvests than self fertile varieties, and some varieties that need a pollinating partner. For these trees, it is recommended to check with a tree stockist to confirm a compatible partner based on flowering time.
The easy way for a gardener to organise their growing and discover gardening ideas.
Growing
Plums are hardy trees and grow very well in the UK, but they can be affected by late frosts. In more northern or exposed areas, it is better to look for varieties that blossom late.
Plums can be big trees, commonly over two metres, and can be much higher depending on the root stock. In small spaces, it is possible to train plums by pruning and tying to supports, with the fan or pyramid shape working particularly well.
The key to success for growing plums is finding a good match for your local climate. A late heavy frost can destroy the blossom on a plum tree and the resulting harvest. If late frosts are particularly common, choose a late flowering variety, or consider growing damsons instead.
Like most types of tree, plums are best planted when they are dormant (without leaves) in late autumn or winter. Dig a hole of sufficient depth and width to easily accommodate the root ball, and fill it with well rotted manure and compost. Consider using a stake to help support a tree until it becomes established, as a young tree in leaf can be blown over in strong winds.
Plum trees like a moist but well drained soil. Do not allow the soil to dry out during the growing season, as this may risk the tree shedding its plums. A tree may need watering in dry periods for the first few years whilst it develops a strong root network.
Depending on the plum variety and local climate, plums should be ready between July and the end of August. Plums should be allowed to ripen on the tree for as long as possible as this will allow their flesh to soften and sweeten.
There are actually good reasons for not pruning plumb trees. Plum trees benefit from being left alone to develop a habit of fruiting, and pruning plums trees in their first few years can disrupt this. There is a risk of introducing disease into the plum tree through pruning. It is recommended only to prune plum trees in hot weather, as pruning in late autumn and winter increases the risk of the tree developing silver leaf disease or canker.
My personal experience is the biggest problem affecting my plum (and cherry) tree is aphid attack. Black fly can easily be washed off the leaves with water – but on a large tree this is not practical.
The real problem is the ‘farming’ of aphids by ants that climb up and down the trunk. There is a simple solution by applying a 10 cm or 3" layer of grease around the trunk about 30 cm or 1 ft up from the ground. The grease stops ants from climbing the tree, provided that the grease is pushed into the bark leaving no gaps.