Pssst, hey, buddy — yes, you with the weeds. There are rules around here about growing stuff like that, so you’d better get rid of them before your HOA’s ticket masters pay a visit to your door.
Here’s how to stay one step ahead of the lawn invaders.
“You can turn a pretty pitiful lawn around with a bit of fertilization, weed control and proper watering,” says Tony Koski, Colorado State University extension turf specialist. “If your yard is in bad shape but has a good distribution of grass, fertilize it to get the turf growing, put down Weed B Gone or other broadleaf weed control, then fertilize again five or six weeks later.”
Check your irrigation system to make sure it’s covering all areas, he says. “Most thin spots are the result of a lack of water, where the sprinklers just don’t give good coverage. The turf can’t compete or block out weeds.”
Certain parts of the lawn will usually have weeds, such as edges near sidewalks and driveways, or in high-traffic areas where people walk. Spot treat those with herbicide to keep invaders under control.
If using organic herbicides such as acetic acid, soaps or clove oil, be sure they don’t splash onto nearby grass; they’re broad-spectrum plant killers. Boiling water is ideal for getting weeds (and grass) out of sidewalk cracks or flagstone patios.
Stressed lawns have groups of weeds that flourish under certain conditions. Growing together in the yard, they’re known as indicator weeds.
Hot, dry soils sport black medic, bindweed, dandelions, kochia, stink grass and yarrow. If the grass is thin and choked with these, increase water to the area or check the sprinklers for coverage.
Overwatered yards host annual bluegrass, common chickweed, crabgrass, violets and ground ivy. Sprinklers may be running too often or too long.
Compacted soil is a favorite of mouse-ear and common chickweeds, goose grass, knotweed, annual bluegrass and prostrate spurge. Core aerate twice per season over two or three years to break up compaction.
Lawns mowed too low are perfect for crabgrass, yellow wood sorrel and white clover. Increase the mower height, keeping grass at 2 to 3 inches tall.
Not fertilizing enough, but over watering? You’ll see black medic, plantains and white clover. Cut back on the water and feed the lawn.
Overfertilizing? Curled dock, henbit, yellow wood sorrel and annual bluegrass will pop up. Calibrate your spreader to drop only what the grass needs, and fertilize in September, early November, May and June.
Five common invaders
Recognizing turf weeds takes practice. Spot the common ones:
Black medic (Medicago lupulina) resembles three-leaf clover but has yellow flowers instead of white. One leaf is held on a separate petiole from the other two.
Kochia (Kochia scoparia), the classic “tumbleweed,” is fuzzy when young with dull green tops and magenta undersides.
Ground ivy (Glechoma hederacea) grows along the ground, having circular leaves edged by large, rounded teeth. Square stems help identify this plant, along with a faint minty odor when crushed.
Prostrate spurge (Chamaesyce maculata) forms a mat of hairy leaves that, when broken, oozes a milky sap that irritates skin.
Knotweed (Polygonum arenastrum) zigzags across the ground on long, tough stems. This weed thrives in dry, infertile soil.
For photographs of weeds, check out the University of California’s weed photo gallery at PMG/menu.homegarden.html.
