Settle on planting distance, hence the number of trees you have room for, before deciding on varieties. This is a difficult decision if you want your trees (when mature) to touch within the row, as you would to maximize fruit production.

Mature size

The mature size of fruit trees depends on (a) how good the site is, (b) rootstock, (c) variety, (d) your training/pruning regime and (e) other management practices.

(a) Site

Site factors include soil, climate, topography, exposure and aspect. If your site is poor, don’t despair. You can ameliorate the soil, control competing vegetation (see ‘How to plant a tree’), provide shelter and/or choose a relatively invigorating rootstock.

Fruit trees grow best in soils which are well aerated and not subject to periodic waterlogging or summer drought. Soils that are thin, compacted or poorly drained are poor. Good signs include the presence of roots to depth 50cm (assuming that there are woody plants close by), a dark upper layer (suggesting the presence of organic matter), the presence of earthworms, a crumbly structure that allows easy root penetration, a texture that is neither too coarse (very sandy) nor too fine (heavy clay), and no evidence (like bluish colours) of poor drainage in the subsoil.

On a regional scale the climate is wet in the west and the growing season is short in the north, and certain varieties are well adapted to these regions, but local factors are just as important. For example, altitude and topography affect damage to blossom from spring frosts, the biggest weather hazard in the southern and eastern parts of the country. Wind frosts are worst on exposed sites. Radiation frosts, which occur on still, clear nights, are worst in hollows or where some barrier (like a fence or building on the lower side of the site) impedes the drainage of cold air.

Exposed sites are primarily windy. Wind causes physical damage, slows growth, is bad for pollinating insects and may cause the crop to fall prematurely. Aspect is important if the slope is steep or exposed. For example, a south-facing slope is relatively hot and dry while a west-facing slope is likely to be exposed to westerly winds. Fences, shelterbelts, other vegetation, walls and buildings can all provide shelter and may re-radiate the heat of the sun.

 (b) Rootstock

Fruit trees are grafted onto a rootstock, which influences vigour and mature size. The biggest range is in apple:

M27 needs very good soil and does not tolerate weed or grass competition. Growth can easily be poor in gardens and yields low. Permanent staking is required because the roots are brittle.

M9 needs good soil and freedom from weed and grass competition, and is the commonest rootstock in commercial orchards. Permanent staking is required. Apple

M26 tolerates average soil conditions and can be grown in grass. Good for many gardens where relatively compact growth is desired. Advisable to stake, at least for the first few years.

MM106 is suitable for poorer soils and wetter climates, and for the half-standard form in the average garden. Advisable to stake in exposed situations.

M25 tolerates a wide variety of soils. Suitable for the full standard form on good sites and the half-standard form on poor sites. Staking not required.

For more information on rootstocks, go to www.keepers-nursery.co.uk

 (c) Variety

Varieties noted for their vigour are often triploids, like ‘Bramley’ and ‘Jonagold’, while others like ‘Discovery’ have a reputation for being compact. This may affect your choice of rootstock but shouldn’t (on its own) determine your choice of variety.

(d) Pruning/training

Pruning/training usually aims to increase crown width (while reducing crown height). However, it can also strongly restrict growth, as in containment pruning and in trained forms such as the cordon and espalier.

(e) Management practices

Competing vegetation, particularly nearby trees and grass, reduce vigour, as do root pruning or partial girdling. Mowing, mulching, watering and fertilizing generally increase vigour.

Planting distance

For apple, published sources suggest average areas per tree of around 2m² for M27, 6m² for M9, 9m² for M26, 15m² for MM106 and 40m² for M25, excluding free space in the inter-row. If in doubt choose a more rather than less invigorating rootstock and plant closely, at least within the row. It’s easier to thin trees or restrict growth than to invigorate weakly ones.

 Layout

The usual planting pattern is rectangular, with rows going up and down the slope on sloping sites. It is also usual to have a greater distance between rows than between trees within the row to keep the inter-row clear, and area per tree is more important than the shape of the rectangle (provided the trees are pruned accordingly). If several rows are planted, a right-angle can be found from a triangle with dimensions in the ratio 3:4:5. Measuring and sighting sticks are helpful to make lines straight. If you’re staking your trees, the stakes should be measured out, lined up and driven in before planting. If you’re anxious about exposure consider planting the more vigorous varieties on the windward side.

Choice of varieties

To choose apple varieties, consult the Rootle search facility at www.orangepippin.com. For other fruit varieties go to www.keepers-nursery.co.uk