Plant spacing in landscape design

When planning your landscape design, critical attention must be given to plant spacing. Too little space will crowd your plants, creating additional maintenance work and more susceptibility to disease. Too much space may result in areas that are hard to fill in later with suitable plants. In either case, your planting may look haphazard and unplanned, not reflecting the time and resources that you have put into the landscape.

In addition, by using the proper plant spacing, you will be getting the maximum effect from the minimum number of plants, leading to less cost. You will also be less likely to have problems with plant interference with the house or other structures in later years.

To arrive at proper spacing, you need to know not only the ultimate height that the plant will eventually attain, but how wide the plant grows. Often, a plant may grow as wide as it is tall, but there are exceptions. For these types of plants, space them approximately as far apart as the height that they will ultimately attain. For example, if a plant normally reaches between five and 10 feet, space them at least seven to eight feet apart. You may want them farther apart than that, depending on your ultimate landscape goals.

Cultural control on your part may influence your spacing decision. Fruit trees, for example, can attain great heights (and widths), but you normally don’t want them to reach their genetic limits. For many reasons, you will want to control their size, keeping them in bounds. Thus, your spacing is influenced by the knowledge that you will be actively pruning them each year, for size control.

When planting close to your house or other structures, you will need to keep the plant far enough away so that it does not create problems in later years. Trees provide a common example. While some shading of your house may be desirable for relief from the summer heat, you don’t want branches growing into the structure, causing damage. This can be controlled to some degree by pruning. On the other hand, the same tree will be sending roots out in all directions, including under your house, if it is too close. This can lead to foundation problems, and roots in sewer pipes.

Also keep in mind that trees can damage your home in wind and ice storms. Some trees are particularly susceptible to breaking, and should be kept far from your house.

Remember that trees also shade other plants and trees. Very large shade trees should be planted at least 50 feet from each other, if they are to develop their best form. Closer spacing will result in a "wooded" effect, which may be desirable in some situations.

Medium-sized trees should be spaced about 35 feet apart. Smaller trees, such as dogwood and redbud, can be spaced from 15 to 20 feet apart. Even small trees should be kept at least seven to eight feet from your house, to develop an attractive form.

A special situation arises in spacing hedge plants. In this case, you want the plants growing together to form a full, dense screen. For lower hedges (three to four feet high), place the plants approximately 18 inches apart. Plants that grow up to eight feet high will be spaced approximately four feet apart, to create a hedge.