Revised December 1997
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Your need for a windbreak is measured by the benefits you can receive from one. Windbreak research has indicated that heat energy savings of up to 40 percent are possible when you use windbreaks. Most of these savings result from reduced wind velocity and, therefore, reduced air infiltration in homes downwind from the windbreak (Table 1). The properly placed windbreak also serves as an effective snow barrier and can improve the working conditions in farmstead areas where you perform winter chores.
Table 1
Wind velocity
| Wind velocity (mph) = | ||||||
|---|---|---|---|---|---|---|
| 5 | 10 | 15 | 20 | 25 | 30 | |
| Wind chill index at 10 degrees F | 7 | -9 | -18 | -24 | -29 | -33 |
| Velocities mph 75 feet in lee of windbreak | 0.5 | 2 | 3 | 5 | 8 | 15 |
| Percent decrease in wind velocity | 90 | 80 | 80 | 75 | 68 | 50 |
Crops protected from wind use moisture and nutrients more efficiently. Windbreaks reduce burning and wilting of crops, often resulting from strong winds, high air temperatures and deficient moisture. However, because of tree root competition, crop yields will be less than normal in a strip about equal to the height of the trees. You can plant grass or legumes in these areas as roadways or turning areas. Crop yields generally decrease at distances about two to 10 times the tree height. In seasons of abundant moisture, cool temperatures and little wind, the windbreak is not likely to increase crop yields.
Windbreaks improve feed efficiency and reduce death losses of cattle fed in open lots. This protection has reduced weight losses in cattle by as much as 50 percent. Studies over a five-year period in Iowa showed that sheltered cattle gained 80 pounds more per year and consumed 129 pounds less feed per hundredweight of gain than those not sheltered.
A windbreak can contribute food and a secure habitat for a diverse wildlife community, including game and other birds and animals. Choices of trees and shrubs can influence the types of birds and animals living there. Where wildlife values are important, two or more rows of evergreens with dense foliage and live limbs close to the ground are recommended for winter cover. You can then add rows of trees and shrubs that will produce wildlife food, such as autumn olive, or wild plum, to the protective rows of evergreens.
Plantings for beautification should contain flowering trees or trees with other colorful characteristics to complement the basic windbreak species.
Studies show windbreaks to be effective as noise barriers where busy highways or noisy industrial plants are nearby. They also provide visual screening. Tree and shrub belts 65 to 100 feet wide are effective in reducing noise from high-speed car traffic. Tree belts 20 to 25 feet wide are effective in reducing noise from moderate-speed car traffic. For maximum effectiveness, tree and shrub belts should be tall, dense and located close to the noise source rather than close to the area protected. Evergreen trees and shrubs are most effective where you desire year-round screening from noise.
Planning your windbreak well in advance is necessary. Make decisions about the types of plant materials that will grow well in your location and soil type. Also consider the windbreak design needed for the purpose and the available area. The design must take into consideration the equipment available for preparing the planting area, planting and maintenance. Order trees in the fall before planting to ensure the availability of desired species of trees. Many of the plant species mentioned in this publication are discussed in publications available at your local MU Extension center, the Natural Resources Conservation Service and the Missouri Department of Conservation District Forestry Offices. On-the-ground technical assistance in soils, plant selection, and windbreak design is also available at those same offices.
As you plan your windbreak, bear the following considerations in mind:
The prevailing winds in winter are north and northwest in Missouri, so protective windbreaks should be located along the north and west sides of your farmstead. The most effective zone of influence includes the distance from the windbreak out to six times the height of the trees. Drifting snow varies with the direction and velocity of the wind, the type of snow and the composition of the windbreak but often piles up behind the windbreak at distances of one to three times the height of trees.
Windbreaks placed too close to houses and other buildings result in snow drifting in the very areas that should be free of snow. Therefore, you should plant windbreaks for winter protection at least 100 feet from farm buildings and feed lots on level land.
If the land slopes steeply to the north or west, you will have to plant the trees closer to the farmstead but never closer than 60 feet from main buildings or drives, if snow drifting is a concern. If your farmstead is close to the south or east side of a public road, where the plantings may necessarily be located across the road from buildings, recognize the possibility of the road being blocked by a drifting snow.
Most winter windbreaks are U, L or E shaped. Because wind and snow whip around the ends of a wind barrier, the ends of the windbreak should be extended approximately 50 feet beyond each corner of the area to be protected. Reinforce corners with extra shrubs and conifers if you desire. Windbreaks do not have to be laid out in hard, straight lines. A curved windbreak on the contour line around the north and west sides of your farmstead is a little more difficult to fence, but it will look more pleasing and be easier to cultivate.
Don't plant across old feedlots, near manure piles or across barnyard drainage ways. Trees, particularly evergreens, survive and grow poorly in such locations. When soils or drainage conditions change drastically, it may be necessary to correct the drainage or change the species of trees and shrubs in the windbreak to match the conditions. If it is necessary to cross field roads, driveways or large ditches with a windbreak, try to make the crossings at an angle to avoid creating direct wind tunnels through the planting.
Note
Don't plant windbreaks where they might create visibility hazards at road intersections
Windbreaks usually require several kinds of trees with different growth characteristics to provide foliage density at various heights over a period of years (Figure 1). As trees grow older, their form and crown characteristics change. The ability of a tree planting to furnish protection depends on the sum total of all tree and shrub foliage making up windbreak height, density and longevity.
Figure 1
Windbreak design.
Example species of trees and shrubs for windbreaks.
Windbreaks with fewer rows
Note
Most species have site limitations (example, pin oak is not suited
to soils with a high pH). To be sure species chosen are suitable to your
specific location, contact your local Natural Resources Conservation Service,
Missouri Department of Conservation or MU Extension center for assistance.
Height influences the extent of the protected area. The taller the windbreak, the greater the area protected and the less land required by the trees. For a quick effect, fast-growing trees that reach maximum height in a short time are the first choice. Because fast growers are usually short-lived, also plant slower-growing tall trees that mature later but remain effective for a long time.
Density influences the extent of downwind protection. Most evergreens have fairly dense, compact tops that retain foliage throughout the year. In contrast, the broadleaf trees and shrubs lose foliage in the fall and cause windbreaks to have different densities in summer and winter. Density depends on the width of the windbreak, arrangement and spacing of species, and the crown height of the different species at various ages.
Foliage density of the middle level of shelterbelts will be provided by the fast-growing broadleaf trees for the first 15 years. After that, evergreens will provide it.
Young trees provide a lower level of density, but after 20 to 30 years you will have to rely on thickly growing shrub species for foliage density near the ground.
For winter protection, the main evergreen planting should always be north and west of the taller broadleaf trees for best control of drifting snow. Evergreens provide maximum winter protection and help trap snow. Shrubs also trap snow and reduce wind near the ground.
Mixtures of species offer more insurance against a plantation being damaged by disease, insects or climatic factors.
Plantations with both deciduous and evergreen species at least 20 feet of space between rows of evergreen and deciduous species.
A five-row plantation makes an efficient windbreak. If limited space prevents planting five rows, it is better to use fewer rows than to crowd the trees. Three rows, with room to grow, will give better long-range results than five crowded rows. Where there is not sufficient area for even three rows, a narrow windbreak of two rows of dense evergreens gives the most practical protection under the circumstances. Staggering the trees in an alternate pattern so they are not directly behind the tree in the next row will allow you to space them a little more closely.
Windbreaks can also modify the summer environment. A well-designed summer windbreak reduces wind velocity but will still allow a breeze for ventilation. Summer windbreaks usually consist of one or two rows of plants located to the south and west of the area to be protected. A one-row windbreak may be either evergreen or deciduous trees. The south row of a two-row summer windbreak usually consists of deciduous shrubs or small deciduous trees, and the row to the north, of moderate to tall deciduous trees.
Locate the summer windbreak about five times the mature height of the trees from the area to be protected. Dense windbreaks, located more closely, reduce wind speed more but may cause an increase in midday air temperature and reduce or eliminate ventilation.
| 15 to 20 feet | 20 to 30 feet | 20 to 30 feet | 25 feet minimum | 15 to 20 feet |
| Row 1 | Row 2 | Row 3 | Row 4 | Row 5 | Row 6 |
|---|---|---|---|---|---|
| Dense shrub | Medium evergreen | Medium evergreen | Medium decidious or tall evergreen | Tall deciduous | Flowering shrubs |
For two-row windbreak, use rows 2-3.
For three-row windbreak, use species listed for rows 1-2-3 or 2-3-4.
For four-row windbreak, use species listed for 1-2-3-4 or 2-3-4-5 or 1-2-3-5.
For five-row windbreak, use tall deciduous and any other four rows shown here.
Note
Most species have site limitations (example, pin oak is not suited
to soils with a high pH). To be sure species chosen are suitable to your specific
location, contact your local Natural Resources Conservation Service, Missouri
Department of Conservation or MU Extension center for assistance.
Plan spacing according to the probable size of the crowns after the trees reach 20 to 30 years of age. It takes longer for trees to form an effective wind barrier at wider spacing, but you can overcome this by staggering the trees in adjacent rows. The delay in effectiveness will be more than offset by the increased growth and vigor of the trees that have adequate growing space. Such trees live longer, retain their lower limbs better and produce more foliage.
Spacing between rows ranges from 15 to 30 feet, depending on the types of trees or shrubs in the adjacent row.
Spacing must always allow for proper use of suitable maintenance equipment.
Between trees in a row:
You can get planting stock from commercial nurseries or from the Department of Conservation's State Nursery at Licking, Missouri. Application blanks for trees from the state nursery are available from MU Extension centers in every county, Natural Resources Conservation Service offices or Missouri Department of Conservation District Forestry Offices.
A partial list of private nurseries carrying seedling trees is available by writing:
Seedling trees will be relatively small and will require good care from their arrival to planting time but are the most commonly used size because of their low cost. Medium- and larger-sized, bare-rooted stock, balled and burlapped stock, and container-grown trees and shrubs will usually produce an effective windbreak two to three years sooner than seedling trees. However, they greatly increase the cost of planting.
Proper preparation of the planting site is important for good tree survival and growth. Except on light, sandy soils where weeds and sod are not a problem, begin control of competing vegetation during the fall before spring planting. Control all competing vegetation, including sod, weeds and brush.
Where the ground is level and erosion is not a problem, plow the entire area in the fall, then disk and harrow it in the spring just before planting.
When erosion may be a problem, prepare a 4- to 6-foot strip in the fall by plowing or using chemicals. Leave a strip of sod between rows to cut down on erosion. Rows should also be aligned on the contour.
If the slope is steep, a circle of sod or other vegetation 2 to 6 feet in diameter may be removed or chemically treated where each tree or shrub is to be planted. Apply the chemical treatment the fall before planting. Plant the tree in the dead patch during the following spring. Be sure the chemicals are appropriate. Follow the label instructions. Pesticides used improperly can be injurious to humans, domestic animals, plants, crops, beneficial insects, and fish and wildlife.
Control of competing vegetation will be necessary for a minimum of three years after planting. If you use mechanical cultivation, it should be shallow to prevent injury to tree roots.
When the trees arrive from the nursery, open the bundles and inspect the trees for damage, mold, overheating and settlement of packing material away from the tree roots. Repack the roots and moisten the packing if needed. If the trees will be planted within a few days, they may be kept in the bundles in a cool, shaded place, protected from freezing.
If planting must be delayed for a longer period, the trees should be heeled in. Dig a trench in the ground in a shady location protected from the wind and spread the tree roots along the trench with the trees upright. Cover the roots with moist soil, refill the trench and pack firmly to eliminate air pockets.
When you are ready to plant the windbreak, remove the trees from the bundle or the heel-in trench as needed and place them in a bucket of water or wet packing material for transporting. Keep the roots wet until the tree is planted. Do not plant in dry soil.
Plant with a planting machine, shovel or tree planting bar. Technical assistance in planning or establishing your windbreak is available as well. Your MU Extension center can also assist you in locating free technical assistance in all aspects of tree care, including planting windbreaks.
Table 2
Trees and shrubs used in Missouri windbreaks
| Species | Soil tolerances | Estimated height after 20 years | Planting zones |
|---|---|---|---|
| American holly |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
<26 feet | Southern Missouri |
| American plum | All | 8-15 feet | All |
| American sycamore | All | 26-35 feet | All |
| Amur honeysuckle | All | 8-15 feet | All |
| Amur maple |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
<16 | All |
| Amur privet | All | 10 feet | All |
| Autumn olive |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
<16 | All |
| Bald cypress |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
16-25 feet | All |
| Basswood | Deep or moderately deep, well-drained or moderately well-drained soils | 26 feet | All |
| Black cherry | Deep or moderately deep, well-drained or moderately well-drained soils | 16-25 feet | All |
| Blackhaw |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
<16 | All |
| Black locust |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
26-35 feet | All |
| Black walnut | Deep or moderately deep, well-drained or moderately well-drained soils | 26-35 feet | All |
| Black willow |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
25 feet | All |
| Bur oak | All | 16-25 feet | All |
| Catalpa | Deep or moderately deep, well-drained or moderately well-drained soils | 26-35 feet | All |
| Chinkapin oak |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
16-25 feet | All |
| Common lilac | All | <16 feet | All |
| Cutleaf staghorn sumac |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
<8 feet | All |
| Eastern cottonwood | All | 35 feet | All |
| Eastern red cedar | All | 16-25 feet | All |
| Eastern white pine | Deep or moderately deep, well-drained or moderately well-drained soils | 26-35 feet | All |
| European alder |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
26 feet | All |
| Flowering dogwood |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
<26 feet | Central and southern Missouri |
| Forsythia | All | <16 feet | All |
| Green ash | All | 26-35 feet | All |
| Hackberry | All | 16-25 feet | All |
| Highbush cranberry |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
<10 feet | All |
| Jack pine |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
16-25 feet | All |
| Kentucky coffee tree | All | 16-25 feet | All |
| Loblolly pine |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
26-35 feet | Central and southern Missouri |
| Medium purple willow |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
8-15 feet | All |
| Northern red oak | Deep or moderately deep, well-drained or moderately well-drained soils | 26-35 feet | All |
| Northern white cedar |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
16-25 feet | Northern and central Missouri |
| Norway spruce | All | 26-35 feet | All |
| Osage orange | All | 16-26 feet | All |
| Pecan |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
26-35 feet | All |
| Persimmon | All | <26 feet | All |
| Pin oak |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
26-35 feet | All |
| Pyracantha (hardy variety) |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
<12 feet | All |
| Redbud |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
<16 feet | All |
| Red maple | All | 35 feet | All |
| Red mulberry | All | <26 feet | All |
| Red pine | Deep or moderately deep, well-drained or moderately well-drained soils | 26-35 feet | Northern and central Missouri |
| River birch |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
26-35 feet | All |
| Russian olive | All | 16-25 feet | All |
| Sassafras | Deep or moderately deep, well-drained or moderately well-drained soils | 26 feet | Central and southern Missouri |
| Shagbark hickory |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
16 feet | All |
| Shingle oak | All | 26-35 feet | All |
| Shortleaf pine |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
26-35 feet | Central and southern Missouri |
| Siberian elm |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
26-35 feet | All |
| Silky dogwood | All | <8 feet | All |
| Silver maple |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
35 feet | All |
| Smooth sumac | All | <8 feet | All |
| Spirea | All | 8 feet | All |
| Sweetgum |
Deep or moderately deep, well-drained or moderately well-drained soils Poorly to very-poorly drained wet sites |
26-35 feet | All |
| Tartarian honeysuckle | All | 8-15 feet | All |
| Thornless honeylocust | All | 26-35 feet | All |
| White oak |
Deep or moderately deep, well-drained or moderately well-drained soils Shallow, dry soils |
16-25 feet | All |
| Yellow poplar | Deep or moderately deep, well-drained or moderately well-drained soils | 35 feet | All |
G5900, revised December 1997