
by Kathy
Roth
Colorado State University Cooperative Extension
Master Gardener
Larimer County
An article last month described wind tolerant shrub and
tree choices that are excellent for use in windbreaks. Resources from Colorado
State University Extension include information on native trees and shrubs, tree
selection, planting and placement. Fact
Sheet #7.225, “Landscaping for Energy Conservation,” details
some principals of landscape wind deflection, discusses evergreen row placement
and use of fence sections as additional shelter. Other excellent resources are
Colorado State Forest Service’s booklet series “Trees for Conservation.”
The “Buyer’s Guide” details each trees’ growth
form, mature size, and other attributes. Using this in conjunction with the
“Planning – Planting – Care” booklet (CSFS#114-0394)
gives information needed to design and plant windbreaks.
In general, when designing a windbreak, the denser the shrubs and trees are,
the better windbreak they make. Dense shrub choices include peashrub, cotoneaster,
lilac, sumac, buffaloberry, mountain mahogany, privet and willow. Dense tree
choices for the foothills include Colorado blue spruce, Eastern redcedar, Pinyon
pine and Rocky Mountain juniper.
Design your windbreak as part of the landscape with rows perpendicular to prevailing
winds—the rows do not need to be necessarily placed on a straight directional
axis. The wind-protected area extends to a distance of approximately ten times
the height of the tallest trees. Wind eddies can form around the ends of a windbreak,
so plantings should extend 100 feet beyond the protected area. Gaps within the
row will funnel and
accelerate
wind, reducing the windbreak’s effectiveness, so it’s better to
plant the same type tree within the same row. Ideally, windbreaks
consist of at least three rows.
Diversity of tree or shrub choice will yield not only a more visually pleasing
outcome, but will increase the disease and insect resistance and enhance the
windbreak as a wildlife habitat. The row closest to the wind should be shrubs
and the row closest to what you are screening should be trees. To determine
spacing between the rows, refer to the plant’s mature size. At maturity,
the sides of each plant should slightly overlap or “touch.”
In general, shrubs need spacing of four to six feet; junipers and cedars need
six to eight feet; pines and spruce need ten to 14 feet. The distance between
rows should be a minimum of eight feet, with a maximum of 15 feet, dependent
upon available space. If windbreaks are planted too close to driveways or roads,
the windbreak can actually cause snow to pile up and drift. It’s best
not to plant trees any closer than 60 to 70 feet from the desired protected
area—snow can drift a distance of three times the height of the windbreak.
NOTE: The attached picture was drawn by the author, Kathy Roth. This is the
windbreak she designed for her property, where the prevailing winds are from
the north and west.
The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.
Gardening and Insect Fact Sheets are available on-line by clicking HERE.
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