What Prostrate Knotweed looks like
A tough wiry mat spreading flat from one central point, with small dull blue-green oval leaves and a papery white sheath wrapping the stem at every leaf joint, almost always in hard-packed ground along driveways, sidewalks and worn footpaths.
Photo: Wikimedia Commons
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Best approach: Spray or dig
Small plants pull easily from moist soil before the mat toughens. Knotweed grows where soil is compacted — along walks and driveways — so core aerate and thicken the turf or it returns every year.
Best products for Prostrate Knotweed
Formulated to kill prostrate knotweed without wiping out your grass — see the timing and chemistry below.
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Scotts Turf Builder Triple Action1
✓ Kills prostrate knotweedBeginner friendlyPrevents crabgrass for up to 4 months, kills dandelion, clover and other listed broadleaf weeds, and feeds. Apply to wet grass, no more than twice a year. Not for St. Augustine. Its label allows centipede, but centipede does better with a stand-alone weed killer and a lighter feeding.
BioAdvanced All-In-One Weed & Feed (22-0-4)
✓ Kills prostrate knotweedBeginner friendly
Scotts Turf Builder Weed & Feed5
✓ Kills prostrate knotweedBeginner friendlyWeed killer plus 26-0-2 lawn food for dandelion, clover and other listed broadleaf weeds. Apply to wet grass. On bahia, wait until mid-April and the third mowing, and make fall applications before Nov 1. Not for St. Augustine. Its label allows centipede, but centipede does better with a stand-alone weed killer and a lighter feeding.
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Herbicide is dosed by lawn size. Pick your yard size for a quick estimate:
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When to treat Prostrate Knotweed
Spray in spring or fall when temperatures are 60–80°F and the weed is actively growing. Avoid summer heat — stressed grass takes collateral damage.
Chemical treatment
A three-way 2,4-D + MCPP + dicamba is the reliable pick — dicamba does the real work here — sprayed spring to early summer while plants are still small, because mature mats shrug it off. On St. Augustine and centipede use only a three-way labeled for them at the reduced rate, never above 90°F. Triclopyr is a cool-season-only alternative (tall fescue, Kentucky bluegrass, ryegrass, fine fescue) — its label warns against St. Augustine, centipede, bahia, bermuda and zoysia. Knotweed germinates near 40°F soil temperature, six to eight weeks before crabgrass, so a pre-emergent (prodiamine, dithiopyr or pendimethalin) must go down in late winter — well before normal crabgrass timing — or in late fall. Skip the pre-emergent anywhere you plan to seed.
Non-chemical management
Core aerate — knotweed is a living compaction indicator and grows exactly where turf roots cannot. Reroute the traffic that caused it (stepping stones, a path) and reseed, or it returns every single year.
How to stop Prostrate Knotweed coming back
Relieve compaction with annual core aeration and stop foot and mower traffic wearing the same line.
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Measure my lawn — it's free →FAQ
What does Prostrate Knotweed look like?
A tough wiry mat spreading flat from one central point, with small dull blue-green oval leaves and a papery white sheath wrapping the stem at every leaf joint, almost always in hard-packed ground along driveways, sidewalks and worn footpaths.
What's the best way to kill Prostrate Knotweed?
Spray or dig. Small plants pull easily from moist soil before the mat toughens. Knotweed grows where soil is compacted — along walks and driveways — so core aerate and thicken the turf or it returns every year.
Is Prostrate Knotweed hard to get rid of?
Prostrate Knotweed is rated moderate to control. Consistent treatment over a season usually does the job.
How do I stop Prostrate Knotweed coming back?
Relieve compaction with annual core aeration and stop foot and mower traffic wearing the same line.
Other broadleaf weeds
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