In the middle of a Big Bend summer, when the lawn is fighting heat and the sprinkler is losing, spurge shows up. Flat mats of it, spreading out from a single root, along driveway edges, in the thin spots under the mailbox, and across any bare ground. Break a stem and it bleeds white. That sap is the surest identification you will get.
Identifying spurge
Spotted spurge and prostrate spurge are the two common ones in Jefferson County lawns and they behave the same. The plant grows flat against the ground in a mat that can reach a couple of feet across from one central taproot. Stems are thin, often reddish, with small oval leaves in opposite pairs. Spotted spurge has a dark red blotch in the middle of each leaf. All of them ooze milky white latex when broken, which can irritate skin; wear gloves.
It is sometimes confused with knotweed, which does not have the sap, and with purslane, which has thick, succulent leaves. Neither of those bleeds white.
Why it appears in July
Spurge is a summer annual that germinates when the soil is hot, above 75°F or so, which puts its start in late May and June here and keeps it germinating through August. It needs light on the soil, so it only establishes where the turf is thin: the strip along the driveway that gets scalped, the dry spot the sprinkler misses, the bare ground where a dog runs, the compacted path to the shed. Each plant sets seed within a few weeks and can produce thousands, and the seed germinates the same season. That is why a couple of plants in June is a carpet in August.
Pre-emergent
The spring pre-emergent applied in late February for crabgrass does not usually last into spurge season. A second application in late May does. Prodiamine, dithiopyr and pendimethalin are all labeled for spurge and safe on established centipede, St. Augustine, Bermuda and Zoysia at label rates. Concentrate on edges and thin areas, because that is the only place spurge is going to come up anyway.
Post-emergent
Young spurge is easy to kill with most broadleaf lawn herbicides. Mature mats with a woody stem are harder and often need a second application.
- Bermuda and Zoysia: three-way products with 2,4-D, dicamba and mecoprop work at full label rates.
- Centipede and St. Augustine: the same products at the reduced rate on the label, and not above the label's temperature limit, which many spurge days exceed. Spray early in the morning on a cooler day. Atrazine-based products labeled for these grasses are effective but have timing and site restrictions.
- Driveway cracks and gravel: a non-selective herbicide, or pull it. Spurge in pavement is where much of the seed for the lawn comes from.
Read the label every time; our post on reading a herbicide label for centipede covers what to look for.
Pulling it
Because spurge grows from one taproot, a whole mat comes up in one pull if you get under the center. Do it before the seed matures, bag it, and wear gloves for the sap. On a small lawn a half hour of pulling in early July prevents most of the August carpet. Mowing does not control it; it grows below the blade.
The real fix: no bare ground
Everything above manages the symptom. Spurge is telling you where the lawn is thin. Fix that and it stops coming:
- Raise the mowing height and stop scalping edges. The driveway strip should be cut at the same height as the rest of the lawn. Our scalping post explains why edges get hurt.
- Check irrigation coverage. Spurge maps the dry spots for you.
- Relieve compaction on paths with core aeration in late spring.
- Plug or sod bare spots in May so there is turf, not soil, when spurge season arrives. See bare spot repair.
In beds
Spurge in landscape beds means the mulch is thin. Top it up to two or three inches, apply a pre-emergent labeled for ornamentals in spring, and pull what gets through. Do not let it seed in the bed; that seed ends up in the lawn.
FAQ
Is spurge sap dangerous?
It can irritate skin and eyes and is toxic if eaten in quantity. Keep it off your hands and keep pets from chewing it.
Why does it come back in the same spots every year?
Because the spots are still bare. The seed is there and the ground is open. Fix the density in those spots and it stops.
Does it die in winter?
Yes, at the first frost. The seed does not.
Can you fix the thin spots as part of service?
Yes. Height, edging and bare-spot work are all part of a maintenance plan.
If your lawn edges turn into a spurge mat every August, reach out and we'll fix the reasons rather than just the weed. We mow and maintain lawns around Monticello, Capps and across Jefferson County.