Of all fruit trees, plums are probably the least fussy when it comes to pruning, certainly they're less demanding than apples or pears. This makes them an ideal choice for gardeners who want to add fruit to their garden but don't have a lot of experience of pruning fruit trees. The pruning techniques that will help a young tree grow into a healthy, heavily-fruiting addition to the garden are slightly different from those required to keep a mature specimen in order and different again to those required to restore a neglected tree back to health. So the hows and whens of pruning plum trees will be dealt with in three sections, young, mature and neglected.
One thing that all ages of plum tree have in common is that they are vulnerable to a disease called silver leaf. This is a fungal infection spread by spores and pruning cuts makes an ideal entry point for the disease. Since silver leaf fungus is more likely to be wind-borne in colder months, plum trees are best pruned in spring or summer on dry, still, warm days. Keep your pruning tools sharp and always use a big enough blade to make your cuts cleanly, this will ensure that you make neat, clean cuts which will heal better and provide less risk of disease. Always clean and disinfect tools after use.
When To Prune A First Year Plum TreeA first year tree is called a maiden and can be bought 'feathered', with side shoots attached or 'unfeathered' without the side shoots. A feathered maiden will be easier for first time fruit growers as it is these side shoots that form the initial branches. You'll make your first cut when you plant your tree preferably in early spring, just before the buds break out. Cut the main leader back to about 60 cm from the ground, just above a bud with at least 4 buds visible on the trunk below your cut for an unfeathered tree, or with 2 or 3 strong looking side shoots for a feathered one.
After this initial cutting you won't need to do much until the summer. If you see any suckers growing from the base of the tree, below the graft point do remove them. These will reduce the vigour of your tree as they're feeding more directly from the roots than the shoots on the grafted on trunk. If you do have blossom during the first year remove it when the flowers die over, it seems a shame but at this stage you want your tree to put its energy into growing good roots.
Your next pruning should be done in late July, when the young shoots have finished growing. Shorten new branches to 20 cm, cutting above an outward facing bud.
Second and Third Year Plum TreesPrune in late July, shorten branches to around 30 cm and side shoots to about 20 cm, remove stems that are crossing and any weak shoots. Always make your cut just above an outward facing bud, this will encourage an open centred tree with good air flow, which will reduce the chance of fungal disease setting in. Keep an eye out for suckers growing from the rood stock or on the main trunk. If you catch buds on the main trunk early you can simply rub them off with your finger with no risk to the tree. If you're struggling with your tree pruning London do find a more experienced gardening friend, or call in an expert tree pruner, to give you a helping hand. Getting the early pruning right and developing a correctly shaped tree in the early stages will pay you dividends in the long run.
Pruning Established Plum TreesCheck for suckers or unwanted shoots on the main trunk in spring and remove them promptly, thinning of the main canopy should be done in July. Focus on removing dead and diseased looking branches first , followed by crossing stems, then branches that don't bear fruit, If, after all of this the tree still looks crowed, remove stems as needed to maintain that open shape which will encourage air flow. You can also shorten top stems and branches that are getting too tall at this time.
Pruning to Restore Neglected TreesThis will need to be done over two or three years, removing too much living tree at one time will send the tree into shock. As always old or diseased branches go first, followed by crossing branches and then with a focus on keeping the centre of the tree open. Always cut so that the final remaining bud or stem faces outward. Your neglected tree is likely to respond to pruning by sending up lots of young shoots which will need to be thinned.
Sometimes You Need to Prune the Fruit Too!In the course of pruning branches you may well be removing fruit. The average plum will give you more than you need anyway and it's better to choose quality fruit that comes from good pruning than to concentrate on quantity. Some plum trees are such heavy croppers that the weight of the fruit can lead to branches breaking. You can generally avoid this problem by thinning fruit, but if a branch does break, remove it or get it removed by a professional tree pruner or surgeon as quickly as possible. A broken branch will act as a magnet for disease that will then spread to the rest of the tree.
Pruning fruit trees can seem challenging initially but you'll soon grasp the principals and can expect to be rewarded with healthy, delicious, home-grown fruit.