(Perma)Culture and Sanity
Windbreaks are dense, tall plantings of trees and/or shrubs that are used to offer protection from excessive winds. Constant winds slow or prohibit plant growth, raise heating and cooling costs and cause stress or harm from exposure to livestock.
In areas where winds are consistently strong for most of the year, providing homes, livestock and gardens with protection from the wind can be one of our most critical design considerations.
To most effectively block winds, windbreaks should run as close to perpendicular to prevailing winds as possible, should be as tall as possible and reasonably dense and—in order to provide year-round protection—should be built on a framework of evergreen trees and shrubs. A practical-yet-minimal windbreak might include one zig-zagged row of tall evergreen trees such as Austrian or Ponderosa Pine and another zig-zagged row of shorter evergreen shrubs such as Juniper planted 15'- 20' to windward.
All species chosen should be wind-tolerant as well as wind-resistant, of course, but ironically it is also important to choose trees that do not block too much wind or turbulence may defeat the windbreak's purpose (a little air movement also discourages frosts). Choose trees that offer their own yields independent of blocking winds (N-fixation, timber, fruits, etc.) to further increase the value of your windbreak. In general, choose trees that will add value to your property, and avoid water-hungry or aggressive trees (eg, poplar, willow, elm) that will compete with nearby crops or trees for greatest benefits.
Windward rows of windbreaks should be especially tough plants such as the junipers or—if even junipers are difficult to establish—extra-tough pioneer plants such as chamisa, apache plume or others adapted to degraded soils and windy conditions.
Water-collecting 'boomerangs' or swales (depending on orientation of slope) should be used wherever possible to divert runoff to the trees. Also plan on irrigating the trees for the first couple years until they are established—drip irrigation is most effective, time-efficient and water-conserving, but may be difficult to implement on the scale of a windbreak.
Wind protection may be necessary to help establish a front line of short shrubs in especially windy and degraded areas. Initial wind protection can come from hay bales, rock piles, open-topped plastic sheets tied to stakes surrounding individual trees (also holds heat and moisture), mounded earth, brush fences, strong trellis or permeable fencing—even large bunch grasses can be used to shield tiny trees until they can take hold. It is also advisable to offer trees more than a foot or two tall when planted some form of bracing, such as loosely-tied ropes to stakes on the windward side.
Plant windbreaks at a distance from homes and outbuildings sufficient to provide protection from fire (at least 125 feet), but closer than 10 times the full, mature height of the windbreak (ie, you have 600 feet of full protection if the tallest trees are Ponderosa pines at 60 feet). For full protection of larger areas, space additional windbreaks at a distance of 10 to 15 times the mature height of the nearest upwind windbreak.
You can create a good, basic windbreak framework with as little as two rows of evergreen trees. Start with a single or double staggered (zig-zagged) row of medium-height evergreen shrubs (such as juniper—ideal in difficult areas because it is dense, tough, wind- and drought-resistant and will establish in areas with very poor soil).
On the protected or leeward side of this first, shorter row, about 15-20 feet away, plant tall evergreen trees about 8 feet apart on center in a single or double staggered row (increase spacing to 10-12 feet if using double staggered rows; can plant closer if water is plentiful, farther in drier areas).
If space and resources allow, continue extending the windbreak on the leeward side with useful plants for humans, livestock and/or wildlife. For diversity and resiliency, include a wide variety of fruit trees and berries, shrubs, wildflowers, bulbs, grasses, legumes and vines.
Windbreaks should be kept from at least 75 feet (if uphill from house) to 125 feet (if downhill) from buildings for fire safety where fires are an issue. Deciduous plantings, less flammable than evergreens, can be placed between the house and the windbreak if well-spaced (1 - 2 times crown width between driplines of individual trees or shrubs).
Keep even deciduous trees and shrubs at least 20 feet from any buildings (if trees are closer, consider them part of the building and give them an additional 20+ feet from the nearest other shrubs or trees). A row of deciduous trees planted on the house side of an evergreen windbreak offers fire protection by deflecting radiation, and by burning more slowly than evergreens would.
Windbreak trees and/or shrubs can be planted twice as closely as their recommended mature spacing, and then thinned to every-other one after 8-10 years. This will give a denser windbreak sooner than planting the trees at their mature spacing, and will also yeild some useful product (poles, firewood, etc) from the thinned trees.
Useful trees and plants can be added to the basic windbreak to provide wildlife/bird habitat and viewing areas or fruits for human consumption, to enhance beauty, etc. Ideally these will include fruit trees and/or useful trees, shrubs, vines, flowers, etc. The greater the diversity (assuming mutually-harmful plants are kept apart), the greater the health and self-maintenance of the resulting winbreak will be.
Trees for poles, fenceposts or tool handles can be included in windbreaks. Plant trees for fenceposts and poles at several times their recommended density so that they grow tall and straight, then thin them as they become crowded (each thinning provides progressively larger posts or poles). Some trees, such as ash or locust, can be 'coppiced' (cut off near the base and allowed to resprout, then harvested again every few years) to provide regular crops of handles, firewood, fenceposts or even small poles.
Hedges are basically small, dense windbreaks and can be used to advantage in confined spaces. Hedges can be formed from a variety of plants, but should be based on evergreen plants if year-round protection is desired (if the hedge is protecting an annual garden, then a deciduous hedge might be perfectly suitable). Hedges can either block or direct winds, and can be used to create protected planting areas if open toward the sun while blocking prevailing winds.
Shape the earth around your windbreak plantings to catch water and divert it to the root zones of the windbreak trees. These water collection areas can be 'swales' (long, shallow, level ditches dug on-contour to intercept water flowing downslope during rains or snowmelt), 'boomerangs' (shallow depressions with channels extending out across slope to collect rainwater and funnel it to the base of individual trees) or broad depressions with water-collecting canals leading in from overland flow sources or rooftops, impermeable pavements, etc. Ideally, all water flowing across your property during rains or snowmelts will be directed either into ponds or into some form of planting depression.
Water newly-planted trees deeply and regularly for the first couple of years and thereafter as needed. Timed drip watering systems are excellent during the first couple seasons as the trees are assured of regular, deep waterings with little water waste. Make sure trees are planted in or near swales or other water collection areas, and make small (10 gallon) watering dishes around the base of each new tree to facilitate efficient supplemental watering.
Maintain mulch around trees at least 2 or more inches deep. Replace mulch as needed, including a high proportion of tree leaves or needles in the mix as trees like a lot of organic matter but don't need—or like—highly-rich soil (in mature forests most nutrients are tied up in existing tree tissues). Plant spike-rooted plants (see list in Useful and Ornamental Plants) around trees to loosen deep soil and shade the topsoil's surface.
Reprinted from (Perma) Culture and Sanity Website