- Choosing tree shape
- Apple Varieties
- Site and soil
- Feeding Apple Trees
- Weeds, pests and diseases
- Winter pruning
- Summer pruning
- Unfruitful and neglected trees
- Re-grafting old trees
- Fruit thinning
Choosing tree shape
Tree shape should be chosen to suit the garden. If space is very limited, the restricted tree shapes – cordon, fan and espalier – are ideal. Cordons are grown on wires between posts. Use four wires, each 30 centimetres apart, the first at 45 centimetres above ground level. Support the wires on strong wooden or steel posts, about 5 metres apart.
Fans and espaliers can also be grown on wires, or on walls or fences. The restricted tree shapes take up little space – trees will be only about 45 centimetres deep and about 180 centimetres high. These shapes are suitable only for dessert varieties.
Where there is a little more space, free-standing spindle-bush trees can be grown. These are supported only by a strong 180 centimetres stake. Spindle bush trees are kept to about 200 centimetres high and about 150-200 centimetres wide. Both spindle-bush trees and restricted trees must have dwarfing rootstocks to keep them small.
If there is plenty of space, open-centre bush trees can be grown. Kept to about 3 metres high and about 3 metres in spread, these trees should have semi-dwarfing rootstocks. Some old orchards have large trees, up to 8 metres high, grown on vigorous rootstocks, which are no longer used, but these old trees are very difficult to prune, spray and pick fruit from.
Apple fruits will not form unless the flowers are fertilised by pollen from a tree of another variety. This means that two or more apples varieties must be planted, unless there is an apple tree, even a flowering crab apple, already growing within about 100 metres. The varieties ‘Bramley’s Seedling’, ‘Jonagold’ and ‘Crispin’ produce sterile pollen and are useless for pollination purposes. Three or more varieties must, therefore, be grown if these varieties are chosen.
Site and soil
Apples will not crop well on exposed sites; near the coast, or over 200 metres above sea level. Do not plant on a north-facing slope, or at the bottom of any slope where frost might gather.
Choose a warm, sheltered spot, not shaded in any way – especially by large trees that would rob the apple trees of food, water and light. Too much shelter, on the other hand, increases the risk of disease attack, because the foliage stays damp longer.
The ideal soil is deep, fertile, well-drained but moisture-retentive, and slightly acidic. But apple trees grow well on most soils, as long as they are well-drained. They can suffer potash deficiency on dry limy soils and, by contrast, tend to be over vigorous and prone to disease on heavy, limy soils.
Peaty soils are too generally too wet and infertile for apples. Replace poor soil, if necessary, to a depth of about 30 centimetres.
November is the best month for planting but apple trees can be planted until the end of March. Decide on the planting site, tree shape and varieties. Remove, or spray off, the existing grass or weeds and dig the soil over a square meter or so. Incorporate a couple of bucketfuls of well-rotted manure or compost at the site for each tree.
Buy the trees and soak the roots before planting. Dig holes 45 centimetres wide and 30 centimetres deep. Drive a stake in each hole to support the young trees. Trim any damaged roots. Test the tree in the hole for depth, and plant at the same depth as the soil mark on the stem. Fill in and firm gently. Tie each tree to its stake.
Space cordon trees about 150 centimetres apart; fan, espaliers and spindle bushes about 240 centimetres apart; and open-centre bushes about 4 meters apart. The quickest to bear fruit are cordons and spindle bushes – often in the season after planting. The more vigorous cooking varieties, trained as open-centre bushes, may take up to ten years to crop well – especially on heavy soils.
The training procedure used will depend on which tree shape has been chosen. Restricted trees – cordons, espaliers and fans – are often bought with the initial training done. Simply tie the shoots into position to hold the existing shape. Surplus shoots, and those that are badly placed and cannot be tied into position, should be removed.
To train trees from scratch, they should be no more than two years old. The wood is still pliable and the young shoots can be tied into position as they grow. Bare-root trees are usually only two years old, but container-grown trees can be several years old and may already have bad shape that is difficult to correct.
For spindle bush trees, tie-in the main leader to the stake. Allow both the leader and the side shoots to develop. In July, tie the side-shoots down into a horizontal position to induce early cropping.
In the winter after planting, release the ties and shorten the first year’s growth by about one-third – both leader and side-shoots. Repeat this procedure in subsequent years until the spindle bush shape develops. Maintain the central stem from which the horizontal side branches arise. Do not allow rival leaders to develop.
For open centre bush trees, shorten the main shoot to about 75 centimetres above ground level. Select four or five of the side shoots that develop, if these are not already present. Shorten these to half their length each year, allowing them to become the main framework branches. Do not allow a central main leader to develop. Remove branches that tend to grow toward the centre of the tree. This is kept open to let in light and air.
Feeding Apple Trees
Apple trees should get 70 grams of general fertiliser, or Fruit Fertiliser, per square metre in February or March each year. The area of the spread of the branches should be used to calculate the quantity. Even quite small trees will need at least 300 grams each on this basis. Fertiliser is essential for good growth and cropping.
If the trees have tended to be vigorous and not produce much fruit, apply 35 grams of sulphate of potash per square metre each year for three years instead, especially on heavy, limy soils.
Apples ripen on the tree and should not be allowed to fall. Pick the fruit when the stalk parts easily. Some varieties must be used quickly – ‘James Grieve’, ‘Worcester Pearmain’, for instance. Others keep for a few weeks – ‘Laxton’s Superb’ and ‘Jonathan’. Some varieties keep well up to March/April – ‘Golden Delicious’, ‘Bramley’s Seedling’. ‘Crispin’, ‘Idared’ and ‘Queen Cox’.
The keeping varieties can be stored in polythene bags with the top left untied and with a few small holes in the bag to allow air exchange. Store only clean, unbruised fruit of varieties known for their keeping qualities. If a refrigerator is available, the fruit can be stored at a low setting.
Weeds, pests and diseases
For the first few years after planting, keep the ground around the trees free of weeds. Simazine can be used for this purpose, applied to clean ground, in March. As the trees get bigger, grass can be grown underneath, but it should be kept short.
- Codling moth grubs hatch from eggs laid on the young fruit and bore in through the ‘eye’. Feeding and growing inside, they eventually eat their way out. Affected apples ripen prematurely and fall off. The pest is very common in town gardens and precautions are often necessary.
- Greenflies cause stunting of shoots and fruit. A kind of greenflies – woolly aphid – produces woolly masses on the branches, and severely weakens the tree. Control is usually necessary.
- Caterpillars may attack the leaves, but damage is usually slight. Red spider mites may attack in warm summers, causing the leaves to go bronze. If damage is severe, control might be necessary. Bullfinches may attack buds. Netting might be necessary in rural areas.
- Apple scab disease attacks leaves, young shoots and fruit – causing black or brown scabs on the latter which sometimes crack. Spraying will be necessary, especially in wet years and wet localities.
- Apple canker is a serious disease causing sunken cankers on branches and trunk. Branches may die. Avoid injury and control apple scab which creates an entry for canker on young shots. Prune out affected branches.
- Powdery mildew causes whitish discoloration of young leaves and shoots. A bad attack weakens the tree. Prune out affected shoots when noticed in May and June.
When all the young apple trees have been given their initial training for four or five years to form their shape, annual pruning will be necessary to maintain the desired shape and to promote the production of good quality fruit.
Apple trees carry the largest, sweetest fruit on branches between two and five years old. To maintain a fair proportion of branches of this age, some of the oldest branches in the tree are pruned out each year and younger ones allowed to take their place. The idea of replacement is the key to pruning apple trees.
There are two periods for pruning – December/January and July/August. Winter pruning encourages growth of new shoots. Summer pruning discourages growth.
This is the main pruning period for the free-standing, open centre bush and spindle-bush trees.
- Start by removing all dead, damaged or diseased branches. Next, select two or three fairly sizeable branches from among the oldest on the tree.
- Make the choice by reference to their position, bearing in mind the correct shape of the tree and the existence of a younger replacement branch. Usually the choice is easy, because an old branch may be crowding a younger one.
- Having removed some old wood, then remove, or shorten, all weak and spindly shoots. The remaining strong, young shoots will eventually make good fruiting wood. Shorten these by about one-third of their length. These general guidelines suit all types of bush trees.
- For the restricted trees, such as cordons, espaliers or fans, less winter pruning is practised. Heavy pruning in winter would encourage them to grow away from their restricted shapes. In winter, just prune out a few old branches, exhausted old fruit spurs and weak, spindly shoots.
Restricted trees produce young shoots each summer. About mid-July, begin shortening back the stronger shoots to four or five leaves, at the rate of a few each week or so, until September. Do not bother shortening weak shoots – these can be removed in winter.
Bush trees that are very vigorous, but unfruitful, should get summer pruning, and no winter pruning for a few years – until cropping starts.
Unfruitful and neglected trees
Old, over-grown trees can be brought back into production by pruning, feeding and spraying. Prune out some of the old wood and thin out the branches. Feed and spray as normal. Old trees that have deteriorated too much, or are of a bad variety, can be grafted with a new variety.
Apple trees can be unfruitful for a variety of reasons, usually the site is wrong, the soil is poor, or there is no cross-pollination. If these reasons are eliminated and the trees have grown very strongly, producing wood and leaves but few flowers or fruit, the problem is over-vigorous growth. This may have been caused by too-severe winter pruning, or by wrong feeding, and it is a tendency of vigorous varieties planted in heavy, fertile soils.
Bark-ringing can be used as a remedy. This involves removing a 1 centimetre strip of bark from around the stem at blossom time. Seal the cut surface with tape or pruning paint. The restriction in the flow of sap encourages the production of flower buds, and fruit eventually.
Root pruning is another remedy for over-vigorous growth and poor cropping. This involves finding three or four major roots, removing the soil and cutting through the roots.
Re-grafting old trees
In December or January, collect young shoots of the new variety. These should be about 30 centimetres long. Tie them into a bundle and place it in a cool corner of the garden with the bottom 7.5 centimetres in the soil. In mid-April, cut down the main branches of the old trees, leaving them about 90 centimetres long. Remove any small branches.
Make a sloping cut on one of the young shoots above the soil mark where the bunch was in the ground. Trim the top end to leave the piece about 15 centimetres long. Make a slit in the bark of a branch stump of the old tree. Insert the prepared shoot, making sure the cut surface is in good contact with the wood beneath the bark of the old branch.
Tie the grafted shoot tightly in place and seal all the cut surfaces with grafting wax, such as Tenax, or wrap thin strips of polythene around to make a seal. Cut the ties as soon as the buds break. Train the new shoots to replace those removed. The first fruit will be produced two years later.
Established apple trees often produce too many small fruits of poor flavour because the tree has not the vigour to swell them all. A certain amount of natural thinning takes place. Only those apples with several seeds actually develop to maturity. Many just drop off after initial development. This usually happens in early July, although it is called the ‘June drop’.
Wait until mid-July when the ‘June drop’ is past. If surplus fruit remains, thin it out to leave one apple for every 10 centimetres of branch length. The apples may not be spaced evenly along the branch, but this ratio can be used as a guide to numbers.