Lawn Weed Control for Southwest Florida Lawns

The Weeds That Take Over Lawns Here

Six account for most of what we treat. Several of them are telling you something about the lawn beyond the weed itself.

Dollarweed

Round, glossy, coin-sized leaves with the stem attached at the middle of the leaf rather than the edge. It spreads by underground runners, so pulling it usually leaves most of the plant behind.

Dollarweed is a moisture indicator. If you have it, the area is staying wetter than the turf wants, and the cause is usually overwatering, a low spot that does not drain, or an irrigation head throwing more water on one zone than another. Treating it without fixing the water means treating it again.

The fix is both: post-emergent treatment for what is there, and a look at the irrigation and drainage so it does not come straight back.

Sedge and Nutsedge

The bright yellow-green one that seems to grow twice as fast as everything around it, so the lawn looks uneven a day after mowing. Sedge stems are triangular. Roll one between your fingers and you can feel the three edges, which is the quickest way to tell it from a grass.

Sedge is not a grass and it does not respond to normal broadleaf weed products. It needs a specific sedge treatment, which is one of the more common reasons a homeowner tells us they have sprayed repeatedly with no effect.

It also reproduces from underground tubers, so a single treatment rarely finishes it. Expect a program rather than a one-off. Like dollarweed, heavy sedge usually means the area is staying too wet.

Crabgrass

Coarse, pale green, growing in a low spreading star from a central point, thriving in exactly the spots where the lawn is thin and the sun is hardest. Driveway edges, sidewalk strips and any area that has been scalped by mowing.

Crabgrass is an annual. It comes back from seed every year rather than surviving in the lawn, which is what makes pre-emergent so effective on it. A pre-emergent applied before the soil warms enough for germination stops the seed before it starts, and that is far easier than fighting mature crabgrass in a St. Augustine lawn, where the products that kill it are limited and the margin for error is small.

If you are fighting crabgrass every summer, the answer is almost always to move the timing earlier, not to spray harder.

Florida Betony

Also called rattlesnake weed. Square stems, opposite leaves, small white to pink flowers, and a distinctive white segmented tuber underground that looks like a rattlesnake rattle, which is where the name comes from.

Betony is a cool-season weed here. It shows up as the temperatures drop and the St. Augustine slows down, which is why it seems to appear from nowhere in late fall and winter. The tubers are the reason it is persistent: kill the top growth and the tuber sends up another plant.

It needs repeated treatment across a season, and fall is when to start rather than when you notice it in January.

Spurge and Doveweed

Spurge grows flat and spreading, with small paired leaves and a milky sap if you break the stem. It loves heat and bare soil, so it moves into thin areas fast in summer.

Doveweed is the one that fools people. It looks enough like young St. Augustine to go unnoticed until it has taken over a section, with thick fleshy stems and narrow blade-like leaves. It germinates late in the season, well after most pre-emergent applications have worn off, which is exactly why it gets established.

Both are strong signals that the lawn is thin. Neither establishes in dense healthy turf.

Why Timing Decides the Whole Year

There are two kinds of weed treatment and the difference matters more than the products do.

Pre-emergent goes down before the weed seed germinates and stops it from establishing. It does nothing to a weed that is already up. Its entire value depends on going down at the right moment, which is set by soil temperature rather than by the calendar, and the window is a matter of weeks.

Post-emergent treats what is already growing. It works, but it is always the more expensive and less complete option, because by then the weed has already taken space the grass wanted and left a gap when it dies.

In this part of Florida there are two pre-emergent windows that matter. One in late winter and early spring ahead of the summer weeds, and one in fall ahead of the cool-season weeds like betony and annual bluegrass. Miss the fall window and you spend the winter treating weeds that a single well-timed application would have prevented.

That is the practical case for a program over calling someone when the lawn looks bad. By the time it looks bad, the cheap option has passed.