How to Get Rid of Spurge in Your Lawn

Clemson describes prostrate spurge as a low, mat-forming summer annual. It grows from a taproot that can reach 18 inches deep, and a single plant can spread as much as three feet across. The sap is milky white. Leaves have toothed edges, and some have a reddish spot in the middle, which is why people also call it spotted spurge. Stems may be smooth or hairy. Penn State describes the same plant lying flat and spreading out from the center, easy to notice along sidewalks and bed edges in summer.

It is not nutsedge. Nutsedge stands up, has a triangular stem, and no milky sap. It is not crabgrass either. Crabgrass is a grass. Spurge is a broadleaf weed, even though the mat can look grassy from across the yard.

A single plant can produce over 1,000 seeds, according to Clemson. LSU notes that spotted spurge spreads by seed and that one plant can produce several thousand. Either way, a mat you ignore in July is next year's infestation.

Clemson says spurge likes full sun, open ground, and disturbed soil, and that a yard full of it often means the soil is compacted. Compaction keeps turf roots shallow, the lawn thins, and the weed gets the light its seed needs. Clemson says the seed germinates once soil warms above 75°F, and that the seed needs light, which is why a tight, taller canopy is the real defense. In beds, Clemson wants about 3 inches of medium to coarse mulch. In a lawn, the stand-in for mulch is mowing at the high end of the recommended height for your grass so soil stays shaded.

Penn State sees it in thin turf and in lawns seeded in late spring or summer, when the new grass cannot close before the weed does. LSU puts germination in mid-spring and a full stand by summer. On a warm-season lawn that lines up with the months Bermuda, zoysia, and St. Augustine are supposed to be thick. If they are not, spurge takes the gap.

Clemson also flags a Sandhills and Coastal Plain problem: a lawn that stays thin and yellow under a carpet of spurge may be dealing with nematodes, not just weeds. That is a soil sample for your local extension office, not a guess you treat with another herbicide.

Pull plants while they are small. Clemson says hand pulling works then and mostly fails once the taproot is deep. Do it before the plant sets a heavy seed crop. Bag the plants if they are already flowering. Dropping them on the lawn just replants the seed.

If the spurge is not up yet, a crabgrass pre-emergent is useful here too. LSU says pre-emergent herbicides that control crabgrass also manage spotted spurge, and lists pendimethalin, dithiopyr, prodiamine, and isoxaben as options labeled for St. Augustine, centipede, zoysia, and Bermuda. Those products have to be down before the seed germinates, then watered in if the label says so. Spurge seed waits for warmer soil than crabgrass, above 75°F in Clemson's account, so the barrier has to still be active when that warmer window arrives. Time the first application off the crabgrass soil-temperature window, not off the day you first see a mat. The crabgrass pre-emergent guide and the soil temperature tracker are how you hit that earlier date. Penn State is clear that a pre-emergent does nothing to plants already up.

If the mat is already growing, you need a post-emergent labeled for spurge and for your grass. LSU lists metsulfuron for young, actively growing spotted spurge on those four warm-season grasses, and says a follow-up may be needed. Plants that sit until late summer get much harder to kill. Penn State lists many broadleaf mixes built around 2,4-D, dicamba, MCPP, or fluroxypyr. Those mixes are a common cool-season answer. They are not an automatic yes on St. Augustine. This site's St. Augustine calendar follows NC State in treating 2,4-D as a product that can injure that grass. Spray only a product whose label names both spurge and the grass you are standing on. Clemson says herbicides on turf that is already stressed, from drought or anything else, injure the lawn. Spray when the grass is growing and not wilted, inside the temperature range printed on the label.

Then fix the opening the weed used. Aerate compacted spots, mow higher, and do not seed a cool-season lawn in the heat of early summer if spurge is the reason the stand is thin. Penn State's point is that a late-spring seeding loses that race.

• Waiting until the mat is wide, then discovering the taproot and the seed crop are ahead of you.
• Spraying a nutsedge killer. NC State lists spurge among the weeds halosulfuron does not control.
• Putting down crabgrass pre-emergent after the spurge is already green. Pre-emergent does not kill emerged plants.
• Using a 2,4-D weed-and-feed on St. Augustine because a Northern article listed that mix.
• Mowing short, which puts light on the soil. Spurge seed needs that light.
• Seeding in late spring and expecting the new grass to outrun a summer annual.