WINDBREAK PLANNING
After more than 25 years the SWCD tree program has helped local landowners establish hundreds of windbreaks.
Most are for energy conservation, but windbreaks also provide effective screening
and reduce noise and dust. The green
color of the evergreen trees looks great in the winter when most of the
landscape tends toward brown, black and white.
Some tips for planting windbreak trees are included below, and the following pictures help to illustrate some of the points.
The single row 18 year old American Arborvitae windbreak
pictured below was planted with trees that were sold by Jo Daviess County SWCD
in 1987. Spacing in the row is
a little close at about 4 feet, but the trees are currently maintaining a solid
screen with limited loss of the lower branches due to shading. Arborvitaes are tough and useful. Mulching with sawdust brought these trees
through the late 1980’s drought years with very limited supplemental
watering. More real world pictures and
explanations will be added to this web page as time allows. If you have pictures and know the history of
your windbreak planting send us an email and we will post it too.
PLANNING
These are the things you should consider when planning your
windbreak:
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The location where the windbreak will be most effective. |
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Do you have enough space for a windbreak? How many rows will you plant? The most effective windbreak has at least 3
rows evergreen trees, but a single row will still be useful. |
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What species are best adapted to the area and your
situation? |
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Is there irrigation available to provide them with the
needed water for establishment if there is a drought? |
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Will the trees create a problem when they reach their
mature size? |
PLACEMENT
Our local prevailing winds tend to come from the Northwest,
but this may vary slightly depending on your situation and topography. A windbreak
should be located so that it’s at a right angle to the prevailing winds, or as
nearly as possible to a right angle. The closer to a right angle, the more
effective it will be.
Ideally the windbreak should be located about 100 feet from the house. At this distance trees 35 feet or more tall shouldl break and lift the wind currents over the top of your home. You can place the windbreak closer but make sure the trees don’t shade the house. Drifting snow on the lee side of a windbreak may also be problem if the windbreak is planted too close to the driveway or the structure that it is intended to protect.
If possible the windbreak should extend fifty feet beyond
the length of the house or the area you want to protect. If you must have gaps in your windbreak to
accommodate paths, driveways, etc., try to make the crossings at oblique angles
so you don’t create your own sort of “wind tunnel.”
NUMBER OF ROWS
Many people plant only one-row windbreaks. The Natural Resource Conservation Service windbreak practice standard requires a three row windbreak, typically using two rows of evergreens and one row of shrubs. In general the more rows you plant, the more effective the windbreak will be, but be sure not to crowd the rows.
After a few years crowding slows growth and weakens the plants. The lower limbs of crowded trees tend to die out due to heavy shade. Trees should be staggered between the rows. Measuring and flagging before digging the tree planting holes helps to visualize how the windbreak will appear and helps to insure a nice even tree spacing.
If there is room for four rows, the best protection is achieved with a row of dense shrubs, a row of medium evergreens, a row of tall evergreens, and a row of medium evergreens. With three rows you’ll get the maximum protection with a single row of dense shrubs, a tall evergreen, and a medium evergreen. With two rows, you’ll want to use a medium evergreen and a tall evergreen. If you only have room for one row ... consider an evergreen with a narrower form, such as American Arborvitae.
SPACING
The
recommended spacing between rows should
be sixteen feet, except the spacing from the last row of evergreens to a row of
shrubs may be reduced to 8 feet.
The spacing between the plants in the rows should be:
|
Tree/Shrub Type |
Multiple-row
Windbreaks |
Single-row
Windbreaks |
|
Dense Shrubs |
3
feet |
2
feet |
|
Medium Deciduous Trees |
9 |
6 |
|
Tall Deciduous Trees |
12 |
8 |
|
Medium Evergreen Trees-(American Arborvitae) |
9 |
4-8 |
|
Tall Evergreen Trees |
16 |
8 |
These spacings give the trees and shrubs room to develop
full dense crowns before they start growing together.
PLANTING AND CARE
If sod is present it is desirable to strip the sod away in
the area around the planting hole to create an area of bare soil 3 feet in
diameter or more. Dig a hole wide
enough and deep enough to accommodate the roots of the trees. A subtle color change can usually be
observed on the stem of the tree at the depth where it was growing at the
nursery. The color change on the stem should
be set at the soil level or slightly above to allow for soil settling.
For trees with spreading roots, such as most evergreens,
it’s desirable to firm up a small mound of pulverized topsoil at the bottom of
the hole and spread the roots around it.
The roots will normally out in the direction they were set in the
hole. Avoid placing the tree so that
most of the roots are directed straight down or worse yet curled and twisted. Trees that have a single main taproot such
as oaks or walnut do not require as wide of a planting hole but the hole needs
to be deep enough so that the entire taproot is covered after the area is
backfilled.
At many locations the soil removed from the planting hole
is darker and more fertile near the surface. If possible break up and remove
excessive root structure from the sod and use topsoil from the upper part of
the hole to help cover the roots. This
is the most fertile and friable soil and it is the most valuable when placed
around the roots. Pieces of stripped
away sod will mostly die when placed upside down with the roots exposed. Since most tree plantings in this area are on
a hillside you can build a little water catchment using the upside down pieces
of sod by placing them slightly beyond the lower edge of the planting
hole. If you need more soil for
backfilling around the tree, strip away more sod and extend and flatten out the
planting site in the area upslope and to the sides of the tree. The slightly depressional area will
help catch additional rainfall and can be raised back up to grade using
mulch if it is available.
If you have water on site you can irrigate to control most of the potential soil settling problems right away, but try not to use so much water that the soil puddles and most of the pore space is removed, especially if the soil conditions are tight. It’s a good practice to check for settling of the backfill soil after the trees have been planted for a while. especially after a drenching rain or irrigation. If there has been some settling it may be necessary to straighten up the tree and add a little more soil to keep it properly aligned.
In many cases
early spring plantings have adequate soil moisture and receive enough rainfall
to get the trees started. If soil
conditions are excessively dry at planting time you really should water right
away. If it refuses to rain a good soaking irrigation is
needed every week for at least the first month . Evergreen trees need to break open their buds
and put on some new growth each spring to survive and get their roots established. In the middle of the summer they can
survive with less moisture if they are well mulched. If there is not much rainfall in late summer and
fall, irrigation is helpful to improve overwinter survival especially in
the first year. All trees continue to
transpire over the winter and help from nature or irrigation is needed to provide adequate
moisture in the root zone before the soil freezes up for the winter.
Probably the most effective method to increase the survival
and growth rate of newly planted trees is to mulch. A two to four inch thick layer of wood chips
or shredded bark mulch will be beneficial in keeping down weed growth and maintaining
soil moisture. Mulch the entire root
zone if possible, but keep the mulch layer very thin in the area next to the
tree trunk. This avoids stem diseases
and tends to discourage burrowing rodents from making a nest and girdling the
tree stem. Weeds and grass growing
around trees impede growth by robbing them of needed nutrients and
moisture. The mulch will control the competing
vegetation and mostly eliminate moisture loss thorough cracks that often form
at the soil surface during dry weather.
In addition the mulch will encourage more infiltration from rain or
irrigation. If there has been some settlingarpund the tree, rake back the
mulch in the settled area and bring the soil back up to grade. If significant cracks have developed at the
edge of the backfill for the planting hole close them up and rake the mulch back over the area.
The only successful windbreaks have live and growing trees. Provide the care to help your trees establish and thrive. Be sure to provide protection from animal and equipment damage. Deer browsing or the rubbing of antlers in the late fall can be a serious problem. Spray-on deer repellants will work if applied regularly, especially after rainy periods, and the browsing pressure is not too heavy. Sometimes temporary fencing is the only practical way to keep the wildlife away from your small trees, especially during the winter
TIME TO GROW
If planned
and planted properly, it will take only a few years before you start
noticing the protection and screeening provided by your windbreak Within 10-15 years the
windbreak should be providing increasingly effective protection for you and your home.
Windbreak tree nursery for transplanting. The trees in the foreground Windbreak grouping from SWCD transplants after 12 years growth.
are Concolor Fir after two years of growth. they are slower growing compared The smaller trees in the foreground are Concolor Fir. The trees in
to the Norway Spruce in the next row. The Norways have been in the nursery the background are Norway and White Spruce. The growth rate
four years. An offset fencing system with a four foot tall wire fence and then at this site is slow because the soils are shallow- less than 2 feet
another single wire electrified
ribbon fence offset by 5 feet keeps the deer out.
over dolomite bedrock.