Grass Cover Between Tree Rows Fact SheetSeptember 2005
Warm-SeasonGrass Cover Between
Tree Rows FactSheet DRAFT
USDA Natural Resources Conservation Service – North Dakota September 2005
Dwight Tober, Plant Materials Specialist
Introduction: Permanent grass cover may be desirable between tree rows for erosion control and other environmental benefits. Tree plantings should maintain weed free conditions with-in row (cultivation, chemical, or fabric)whenever possible, but large areas between rows may be seeded to less competitive, shallow rooting warm-season grasses such as blue grama and sideoats grama. These native warm-season species have their highest water use in mid-summer after the trees and shrubs have already leafed out and started active growth. An additional benefit of warm-season species is the opportunity to apply glyphosate herbicide to cool-season weeds (bromegrass, quackgrass, dandelions, etc.) when the blue grama and sideoats grama are dormant in early spring and late fall.
Seeding: A garden-like, clodfree seedbed should be prepared prior to seeding. Tillage should be shallow and the final seedbed must be relatively firm. An adult footprint should be barely visible. If the area is broadcast seeded rather than drilled, then enough loose soil must be available to cover most of the seed. Some seed on top the ground is desirable and is an indication that the seed has not been planted too deep. After raking or harrowing the seed into the soil the new seeding should be roller packed. If a roller is not available this can be accomplished by driving over the area with a wide-tired vehicle such as a garden tractor or four-wheeler. Blue grama seed is small (750,000 seeds/lb) and sideoats grama seed is large (180,000 seeds/lb). Seeding the two species separately may simplify seeding rate calibration. Drop spreaders or whirly-bird type spreaders are usually used to broadcast the seed. Adjustment is accomplishedby increasing or decreasing the size of the opening. An agitator mechanism is beneficial to keep the seed flowing. Seeding rates can be decreased when using a drill because of the more precise seed placement. Seed is calculated on a pure live seed (PLS) basis which is purity x germination x bulk seed. Either species may be seeded alone at double the seeding rate. Blue grama would be the best species to seed alone because it is less deeply rooted and also more tolerant to mowing.
Warm-Season Native PLS lbs/ac
Percent ofBroadcast
Species Varieties/SourceTotal MixSeeding Rate
blue gramaBadRiver50%2.5 to 5.0
sideoats gramaKilldeer, Pierre50%7.5 to 15.0
Weed Control: Mowing is the best procedure for weed control because of the extreme sensitivity of the young tree and shrub seedlings to most broadleaf herbicides. Both grass species have vigorous seedling growth and should establish quickly. However, mowing 2 to 4 times for weed control during the year of establishment may be desirable, especially if weed density is thick enough to canopy over and shade out the new grass seedlings. A mowing height of not less than 3 to 4 inches is desirable.
Mowing or Not: Blue grama and sideoatsgrama are tolerant of mowing andare relatively short (10 to 18 inches) in stature when left unmowed Leaving the area unmowed is desirable for wildlife use andother environmental benefits. Frequent mowing reduces rooting depth of the grasses and provides less water competition for the tree and shrub species. Mowing the grass prior to winter will also reduce the cover for mice and voles and lessen the opportunity for rodent damage.
Fabric Mulch Plantings: Seeding grass between the fabric strips as soon as possible is desirable to prevent weed competition, especially from invasive species such as Canada thistle and wormwood. Tillage is also an option, but care must be taken not to pull up the edges of the fabric.
Frequent tillage may cause soil degradationTree roots can be damaged.
If cool-season grass cover is maintained betweenWhen fabric is not used with-in row weed control can
tree rows frequent mowing will help reduce grassbe accomplished by tillage (hand hoeing or rotary
rooting depth and water competition.tree cultivation) or herbicides. Glyphosate works
well when trees are larger and not as sensitive to drift.
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