Spacing fruit trees is different for a backyard orchard than for a commercial orchard. The spacing of the trees are affected by the type of tree, the dwarfing characteristics of the rootstock, the soil quality, and the tree height and canopy size expected of the mature tree. Planting the fruit trees too close together can cause them to crowd out and shade each other, while planting them too far apart will prevent adequate pollination.
Controlling Tree Size
It is important to begin pruning early to control and maintain the size of the fruit tree. The height and the width of the canopy of the fruit tree must be limited where there is a limitation of space. If the fruit trees are allowed to grow out of control, they will shade and crowd each other with too much foliage, which will hurt the fruit production of the trees, as well as hurt the trees themselves.
Placement of Trees
The fruit trees must be planted so that they receive plenty of sunlight. There must be plenty of air circulation between them to prevent mildew and mold. It is preferred to plant the fruit trees on a slope rather than at the foot of a slope to avoid "frost pockets" where cold air collects. Plant the trees far enough away from any house or building to protect the house from wind damage so that the tree does not fall on the house. Do not plant the fruit trees too close to a house or other building in such a way that the house would shade the trees and not allow the tree enough sunlight to grow well. For the same reason, the fruit trees should be planted away from hedges and fences that would keep sunlight off the tree. Good soil quality requires wider spacing because the canopy will grow out wider.
Dwarfing Rootstock Size
The dwarfing characteristics of the rootstock which determine the mature size of the tree affects the amount of spacing required as well as the type of fruit. Standard trees grown from seed require more space than those made by grafting onto a dwarf or semi-dwarf rootstock. Full size fruit trees generally should have 20 to 24 foot spacing. In the case of apple trees, the standard full-sized trees should be planted in a 35' by 35' area, at least 25 to 30 feet apart. Semi-dwarf apple rootstocks only need to be planted in a 12' by 12' area, or about 10 to 20 feet apart. Dwarf apple trees only require a 10' by 10' area, or 8 to 12 feet apart.
Type of Fruit Tree
The type of fruit tree as well as the size of the fruit tree when it has matured determines the amount of space that should be allowed for each tree when planting. Fig trees should be planted in an area 20' to 30' square in a sunny location. Citrus trees need to be planted 8 feet apart. Dwarf apple, sweet cherry, peach and plum trees can be planted in a 10' by 10' area. Dwarfed pear trees, however, need a space of 12 feet by 12 feet.
Space is required for tractors to pass between the fruit trees in a commercial orchard, whereas the backyard orchard does not require as much space. Standard full size trees or rootstocks are generally planted in commercial orchards. Most standard sized fruit trees that are expected to grow to a height of 20 feet are generally planted one per 20 by 20 foot area. Full size sweet cherry trees grow 30 feet high and require more space to grow, needing an area of 20 by 25 feet. Apple trees grow to a height of 20 to 25 feet and require an area 35 by 35 feet.
Because the average backyard is 90 feet by 100 feet, smaller rootstock trees, either dwarf or semi-dwarf trees are preferred for these, as more than one full size tree will not fit well into the space. For pollinating purposes, two or more fruit trees of the same type should be planted next to each other, unless multiple varieties are grafted onto the same tree. Also, the fruit trees can be planted closer together. High density planting of fruit trees can be done in one of three of the following ways or any combination of them to make the best use of limited space.
Planting Several Trees in the Same Hole.
Two, three, or four trees can be planted in the same hole, so that their trunks are spaced 18 inches from each other. This grouping of trees can be planted in the center of the recommended area measuring 10 by 10 feet for four trees, down to 8 by 9 feet for a two-tree grouping. These must be pruned regularly to prevent one of the trees from shading the other trees in the group.
This is a method of training a tree to grow in a narrow, two-dimensional manner by pruning, so that it will grow flat against a wall or a trellis. Fruit trees to be espaliered should be planted against walls that face toward the sun most of the day.
Planting a Hedge
A hedge of fruit trees can be planted in a row to grow together into a privacy curtain. The trees are spaced about 3 to 6 feet apart by driving stakes into the ground where the trees will be planted and a string looped around the stakes. The trees are then planted next to the stakes.