WOODY ORNAMENTALS AS WINDBREAKS
WOODY ORNAMENTALS AS WINDBREAKS
In flat places where there is no barrier to deter it, the wind often blows over the land with a good deal of force. The force of the wind is often broken by a windbreak of some type. While usually a clump or row of trees and shrubs serve to break the force of wind, a windbreak can also be a fence, other plants, or anything that will serve as a barrier to the winds force. Although an effective woody ornamental windbreak may take 20 years to grow, the benefits it will produce are often worth the wait. While serving as a protectant against the wind, a windbreak will also: reduce fuel costs, protect property from high winds, reduce soil blowing, keep snow from drifting against buildings, attract wildlife, protect livestock, and increase land value and beauty.
The distance that wind protection extends from the windbreak's leeward side is directly proportional to its height. The most effective zone of protection extends to a distance of six to eight times its height, although some protection does extend to a distance of 20 times the height. A good windbreak should reduce the wind velocity by half for distances up to 10 times the height. The general distance allowance between the windbreaks and the area to be protected should be 100 to 150 feet (no more than 300 feet).
A moderately dense windbreak will reduce wind velocity over a greater leeward distance than will a very dense windbreak. Windbreaks should be at least three rows wide (5 rows is better) to be the most effective. The tallest growing trees (preferably evergreens) should be in the center rows, while the shorter trees and shrubs are best placed in the outer rows.
The windbreak should extend about 100 feet beyond the area to be protected in order to provide the best protection as winds shift. Rows of trees should be spaced about 10 to 20 feet apart, while each tree should be spaced between 8 and 18 feet apart within the row, depending on the size of the tree.
Woody ornamentals planted as windbreaks should include a mixture of deciduous and evergreen trees and shrubs. The following table documents the height and spacing required of a variety of species:
SPECIES & APPROX. HEIGHT* SPACING BETWEEN SPACING WITHIN ROWS (feet) ROWS (feet)
Austrian pine Tall 16-20 14-18 White pine Tall 16-20 14-18 Scots pine Medium 16-20 14-18 Red pine Tall 16-20 14-18 White spruce Medium 14-18 12-16 Douglas fir Medium 14-18 12-16 American arborvitae Medium 10-12 8-12 White cedar Medium 10-12 8-12 Russian olive Short 10-12 8-12 Lilac Shrub 4-12 2-5 Viburnum Shrub 3-12 2-4 Honeysuckle Shrub 3-12 2-4
* Tall: 50-60' Medium: 30-50' Short: 15-25' Shrubs: 6-10'
Most of these species should be planted as early in the spring as possible. Windbreaks should be planted at right angles to the prevailing winds (usually westerly in Michigan, therefore the wind-break should run north and south). Most of these varieties are available in garden centers, nurseries, mail order nurseries, and soil conservation districts.
Agriculture Information Bulletin 339 : "Windbreaks for Conservation".