Proper spacing for landscape plants often seems to create confusion. We can not uniformly recommend exactly how far apart plants should be placed. The actual spacing depends on what effect is to be achieved, the ultimate mature size of a plant and how it is to be pruned and maintained.
In addition to the way plants are used for landscape effect, plant spacing may vary with the gardening budget. We want to get the maximum effect from the minimum number of plants. On the other hand we want to place trees and specimen shrubs so they may develop fully without crowding each other, the house or other structures.
Before selecting the exact spot for a tree or shrub, determine what the ultimate size of each plant may be. Nursery personnel, catalogs, garden books and extension publications are all sources of such information. Specific varieties may indicate altered plant form from spreading to upright, weeping or dwarf. Do not confuse spread of such varieties with normal plants. Very new varieties may not be found in books, so get information on the specific plant size at the point of purchase.
Many plants, such as shrubs and round-headed trees, grow about as wide as they grow tall. If figures for width can not be found, estimate from the ultimate height. A plant that may grow somewhere between 5 and 10 feet tall might be planted about 7 to 8 feet apart. A shrub that may be known to grow between 2 to 5 feet tall may require a spacing of about 3 feet. Not all plants fit such a generalization. Very low plants often spread considerably more than their height, and upright plants do not have a spread anywhere near the height.
Placement from the house, or from other shrubs is about one-half the ultimate spread, or for two different plants, one-half of the total spread for both plants. Small shrubs should be planted at least 2 feet from a house foundation, medium shrubs about 3 feet and tall shrubs 4 to 5 feet away. An 8-foot shrub next to a six foot shrub should be spaced about 7 feet apart.
Spacing plants in hedges is another matter. Plants must be spaced closer together to form a full, dense screen. Low hedge plants (3 to 4 feet high) should be spaced about 18 inches apart. Tall hedge plants will need to be spaced 3 to 4 feet apart.
Low ground cover plants may be spaced in regard to how fast a complete cover is wanted. Cost may also be a determining factor. Remember that 100 plants at a 6-inch spacing will cover about 25 square feet of bed area. At a 12 inch spacing they will cover 100 square feet, and at a 24-inch spacing they will cover about 400 square feet.
Trees, especially large shade trees, should be placed well away from the home to avoid later maintenance problems. Strong-wooded shade trees such as oaks should be planted no closer than 20 feet from the house, but soft wooded trees such as soft maple should be planted at an even greater distance. Large shade trees should be planted about 50 feet from each other.
Trees of medium size such as red maple or river birch should be spaced about 35 feet apart. Small trees such as dogwood, redbud, hawthorn or crab may be planted 15 to 20 feet apart and no closer than 8 feet from the house when used as an accent or corner planting.
- © 1988, International Society of Arboriculture. All rights reserved.
