Plum Tree

Latin Name: Prunus Domestica
Light: full sun
Soil: very tolerant of soil conditions
Plant to Harvest Time: A 2 year tree will produce fruit 3 years after planting.

Description
Plum trees should not be the first choice of fruit tree for the totally inexperienced gardener, but with a little knowledge they are not too hard to grow. They can be grown to suit almost all garden sizes, and may well outlast you with a life of 50 years.

Choosing Your Plum Tree
Give careful consideration to what type of plum tree is best for you. Buying a plum tree which might grow to 9m (30ft) tall producing masses of cooking plums is not a good idea if you have a small garden and want eating plums!

Size

Pyramid trained plum trees (B) are free-standing and will grow to an eventual height of 2.5 m (8 ft). These are a good form for a smallish garden - their spread will be about 1.6 m (5 ft). This form of tree has branches radiating out in random directions from a straight central trunk.

Bush trained plum trees (C) are free-standing and are taller than the pyramid form - around 4m when mature. They do have one advantage over the pyramid form however, the branches and foliage is held around 1 m (3 ft) high from the ground - this makes mowing around the tree  much easier. The downside is that some of the fruit will be too high to pick without the use of a ladder.

Half Standard trained plum trees (D) are again free- standing and will grow to a height of around 6 m (20 ft). This is a largish tree and only suitable for medium to large gardens. It will produce a mass of plums each year, most of them needing a ladder to harvest.

Standard plum trees (E) reach a height of around 8 m (28 ft) at maturity - on your own head be it if you plant one of these in anything but a large garden. They will produce enough fruit to feed your entire neighbourhood and you will definitely need a decent sized ladder to pick most of the fruit.

Where To Grow Your Plum Tree
Firstly, plan the position of the plum tree according to it's eventual size at maturity. Allow enough room so that it is not crowded.

Plums have three main needs, warmth (especially important at pollination time, light and moisture. Plums flower earlier in the season than most other fruit trees, so they should not be planted in a frost-pocket. If your garden is in a cool area, avoid early flowering varieties - good varieties to choose are Czar, Victoria or Marjorie's Seedling.

Plum trees prefer to be positioned in full sun, although some shade in the morning or afternoon will not affect them much.

As far as moisture is concerned, do not plant in a water-logged area, but make sure the soil is unlikely to dry out. Don't plant them near other trees which will simply deprive them of the moisture they need. 

Planting Your Plum Tree
Soil preparation is best done a month or more before planting so that the soil has time to settle. Dig a 60cm (2ft) deep by 1.2m (4ft) square hole, incorporating as much organic material as possible - aim to get the soil crumbly.

If the tree is being planted in soil which has previously been fertilised for other crops, do not add more fertiliser - too fertile a soil will result in too much tree growth at the expense of too little fruit growth. If the plum tree is being planted in a lawn, prepare as above, working in three handfuls of bonemeal or other long-lasting fertiliser.

Planting is simple - in basic terms, dig a hole large enough to easily take the roots, place the tree in the hole and cover the roots with soil up to the surrounding ground level. Simple enough, but bear in mind a few points.

Don't add any fertiliser to the soil at this time - it may burn the roots and it will only encourage tree growth at the expense of fruit growth.

The tree should be planted to the same depth as it was in the pot (or the soil mark on the trunk in the case of bare-rooted trees). If in doubt, make sure that the joining point between the rootstock and scion is at least 5cms (2in) above ground level (see left). Having planted the tree, firm  down the soil using your boots to ensure the soil is in good contact with the roots - water well if the conditions are dry.

Plum trees should be supported with a stake for the first couple of years of their life. The stake should be 15cm (6in) or so from the main stem. Tie the trunk to the stake at 30cm (1ft) intervals using plastic ties available from garden centres - do not use wire or anything which could cut into the tree trunk. The ties will need to be checked for the first couple of years to ensure that growth of the tree trunk has not caused them to become too tight.

Care of Plum Trees
With newly planted trees, check in their first winter that they are not lifted by frost, and provide them with water during dry spells. Plum trees grown against a wall or fence will need more regular watering throughout their life.

With more mature trees, very little care other than pruning and thinning (see later in this article) is required. Your plum tree will definitely thank you for a layer of well-rotted compost spread around, but not touching, the trunk. Early spring is the best time for this, to help preserve water and keep weeds at bay. An autumn application of a long lasting fertiliser such as bonemeal will keep them well fed and ready for growth next year.

Because plum trees have lots of roots near the surface, they will often produce lots of suckers (mini-trees) for 3 metres (9 foot) around the trunk. Regular cutting of these suckers will keep them under control. A more permanent way is to gently dig away the soil to the point where the sucker joins the main root system. Simply pull the sucker away from the root. This will slow down the production of suckers considerably.

Thinning Plums
Plum trees can be a bit erratic in producing fruit - one year they produce too little and the next year they produce too much. In years when they produce too much, it's best to remove some fruit before it matures to ensure a good crop next year and also better quality fruits this year. The other danger of producing too much fruit is that the branches may not be able to support their weight and they may break.

Thin the fruits at two stages in the year. First in late May when the fruits are beginning to form, the again in mid-July when the plums are about half their full size. First, remove any damaged or diseased fruit. Then, aim to thin the fruit so that there is enough room for the plums to develop without touching each other - about 7cm (3in) between each plum.

Supporting Branches
If the weight on some of the branches looks like it may cause them to break, it will be necessary to support the branch with a stake from below. Where this is done, pad the branch with some sort of material at the point it is supported by the stake. This will prevent the branch rubbing on the stake and maybe letting disease in.

Pruning Plum Trees
There are two considerations when pruning plum trees. Firstly to establish a good shape, secondly to avoid any infection with silver leaf disease. Click on pests and disease in the left hand menu for a detailed description of silver leaf disease.

To avoid silver leaf disease, prune young trees in when they are growing strongly, late spring to early summer is the best time, do not prune in the winter. For older trees, also  avoid pruning in May and September to October. Try to make the pruning cuts as cleanly as possible, and avoid crushing the wood. If any larger sections of branch are to be pruned, seal the cut with a protective sealer available from garden centres. Burn any diseased or dead wood.

Pruning of plum trees depends on the form wanted - pyramid, bush, standard or half standard. Pyramid trees are pruned in a different way from the other forms.

Harvesting and Storing Plums
Plum trees will begin to produce fruit at four or five years old. Leave the plums on the tree until they are ripe and ready to eat. Ripe plums will be produced over a month or so and it is best to pick a few but often over this time. Any diseased fruit should be removed immediately because they will only attract diseases and wasps.

Ripe plums keep for only a few days and are best stored in the fridge. If you want to keep plums for longer, pick them when they are slightly under-ripe, placing them in a paper-lined box in a cool dark place.