Weeds in lawns offer clues to control

Aaahhh, summer.  The lazy days spent clipping the lawn, neatly trimming the edges and grass so that the carpet rolls along in one, smooth swath of green.  Nothing more satisfying than gathering up the tools and locking them away, turning to view the glory that is….

 …a dandelion, popping up like a summer festival tent smack in the center of the turf.  Soon it has friends and family surrounding it, while bindweed and black medic nestle in the turf, and kochia accents the edge. 

 If you’re struggling with weeds invading your lawn, before you reach for the super-nuclear chemistry, stop and consider: those weeds tell you what the grass can’t about conditions in the yard. 

Stressed lawns have groups of weeds that flourish together under similar conditions.  Some like hot, lean soil; others prefer cool shady spots.   Growing together in the yard, they’re known as indicator weeds, and they help homeowners sort out problem lawn spots.

Before yanking them out, make a list of them to see what type of care your lawn needs.  Here’s a primer on indicator weeds and what they can tell you:

 – Hot, dry soils sport black medic, bindweed, dandelions, kochia, stink grass and yarrow.  If the grass seems thin in spots with these weeds, increase the water to this area, or check the sprinkler heads for coverage.

 – Over watered yards have plenty of weeds.  Annual bluegrass, common chickweed, crabgrass, violets and ground ivy plague chronically wet lawns.  Sprinklers may be running too often or for long periods.

 –  Compacted soil is a favorite of mouse-ear and common chickweeds, goose grass, knotweed, annual bluegrass and prostrate spurge.  Core aeration several times per season over two or three years helps break up compaction. 

– Lawns mowed too low have crabgrass, yellow wood sorrel, and white clover.  Increase the height on the mower to keep grass at two to three inches tall.

 – Not fertilizing enough, but over watering?  You’ll see black medic with plantains and white clover.  Cut back on the water, and feed the lawn.

– Over fertilizing?  Curled dock, henbit, yellow wood sorrel and annual bluegrass will pop up.  Fertilize lawns in May, September and November, and calibrate your spreader to drop only what the grass needs.

Recognizing turf weeds takes practice. Two websites can help you discover what’s invading your lawn, the North Carolina State University’s turf files or Michigan State University’s turf weeds.net.  They’ll take you step by step through a key to identifying what weed you have.  Then jump back onto the Colorado State University turf website to check for control tips that work in our area.