A cold, blustery winter wind can make a chilly day very miserable. In heavily wooded areas the effects of wind are minimized by the trees, and in cities buildings affect the wind. But larger suburban and rural properties often have wide open spaces where the wind can race unfettered to infiltrate homes with cold air. A well-designed windbreak can reduce the chilling effects of winter winds.
A windbreak, or a hedgerow of shrubs and trees, can also be used to buffer unwanted noises and screen unsightly views.
A windbreak consists of any type of barrier designed to slow down wind velocity and redirect the flow of wind. A good windbreak will not create excessive turbulence or wind eddies. Effective windbreaks do not stop the wind, but break its forward movement to slow it down. Solid barriers such as walls and buildings create unexpected wind currents and wind tunnels, often with increased velocity and unpredictable direction. Windbreaks composed of living plants allow some of the wind to slowly penetrate, making them a more effective buffer.
Examples of windbreak materials include picket and board fences designed with gaps between pickets, earthen berms, and rows or hedges of shrubs and trees. Temporary windbreaks can be made out of picket fencing, 60% shade cloth or other materials until a permanent screen is established.
The lee (the sheltered area away from the wind) produced by a windbreak is proportional to the height of the barrier. Areas closest to the windbreak will be the calmest, with wind velocity gradually increasing with distance from the windbreak.
The effective zone of protection created by a windbreak is approximately 25 times its height, although maximum wind reduction occurs in a range of 5 to 8 times the height of the screen. Therefore, if planning a windbreak 25 feet tall, it should be located 125 to 200 feet (5 to 8 times 25 feet height) from the house or area to be protected for maximum utility. A 10 foot windbreak provides maximum protection to 75 feet and some reduction of wind (about 10%) up to 250 feet.
The following criteria are helpful in planning an effective windbreak:
- The optimum solid space or foliage density for a windbreak is about60%. Fences with 1 inch pickets and 1 inch gaps would meet this condition.
- Windbreaks are most effective when they extend to the ground. Do not remove lower branches of trees and shrubs.
- The depth of the planting is important as it relates to the ability of wind to penetrate. For most evergreen plants, two or three rows are sufficient, but for deciduous plants four or five rows may be necessary. Rows should be staggered. A mix of deciduous and evergreen plants is also effective and will provide diversity and interest
- For small properties, a well-maintained hedge, wider at the base, serves as an effective windbreak.
- Where space allows, wide windbreaks can be designed to lift wind up and away.
You can mimic nature by starting with low growing plants on the windward side and increase height within the rows. For example, the first row might be pampas grass or holly, the second row elaeagnus, larger hollies, Eastern red cedar or other junipers, and the third row pine, cypress, oaks or other tree species.
When selecting plants for a windbreak, choose only the hardiest. Species occurring naturally in east Texas are some of the best candidates since they are adapted to our environment. Plant lists are available, and you can observe local landscapes for good examples of hardy plants.
Reducing highway noise or other unwanted sources of sound can be achieved in a very similar manner as constructing windbreaks. Evergreen shrubs and trees do the best job of screening constant noise and unwanted views.
Mixed tree and hedge rows used for wind, visual and sound breaks also make a great wildlife habitat. By choosing plants with berries or other food sources, you can have the added benefit of drawing and maintaining a diversity of birds and animals on your property.
Use of good horticultural techniques will make your investment in a living screen successful. Supplemental water, easily applied through a temporary drip or trickle system, will help assure plant establishment during the first two critical years, especially during droughty summers. By planting in the fall, your plants will have the maximum amount of time to become established before summer arrives.
Keeping the area free of weeds and grass around the base of the plants will speed establishment. Find a cheap source of mulching material such as spoiled (and weed seed-free) hay, pine straw, or wood chips, and apply over the area to reduce weed competition and help maintain soil moisture. Use labeled pre and/or post-emergent herbicides, if needed, to further reduce weed competition until the hedgerow grows sufficiently to suppress weed growth.
I co-authored with Dr. Bill Welch a publication on windbreaks for the Texas coastal areas when I was an Extension horticulture agent in Corpus Christi. It has more details and is the source of the illustrations.