Identifying the Weeds Actually Growing in Central Florida Lawns

Weed control products are category-specific, and putting a broadleaf product on a grassy weed does nothing at all. Before buying anything, work out which of three categories you are looking at.

The three categories

Broadleaf

Wide leaves with a branching vein pattern, growing distinctly differently from the grass around them. Dollarweed, clover, chickweed, spurge, Florida betony.

These are the easiest to control selectively in turf, because they are botanically distant from grass.

Grassy

Look like grass, because they are grass. Crabgrass, goosegrass, torpedograss, Bermuda invading St. Augustine.

Much harder, because anything that kills a grass tends to kill your grass. Control is largely about prevention with pre-emergent, and about the fact that a dense, correctly mown lawn crowds them out.

Sedges

Look like grass at a glance and are not. The tell is the stem: sedge stems are triangular in cross-section. Roll one between your fingers and you can feel the edges. Grass stems are round.

Sedges also tend to grow faster than the surrounding lawn, so they stand proud a couple of days after mowing. They need sedge-specific products — broadleaf and grassy herbicides do not touch them.

The ones we see most here

• Dollarweed. Round, coin-like leaves with the stem attached in the centre. Almost always indicates too much water — it is a wetness indicator as much as a weed.
• Doveweed. Looks deceptively like St. Augustine, which is why it spreads unnoticed. Emerges late, loves wet ground.
• Nutsedge. Triangular stem, faster-growing, yellow-green. Reproduces from tubers, so pulling it spreads it.
• Torpedograss. Aggressive rhizomatous grass, genuinely difficult, and honestly the hardest thing on this list to control in St. Augustine.
• Crabgrass. Prostrate, light green, spreads from a central point. A summer annual, so pre-emergent timing is the control.
• Florida betony. Also called rattlesnake weed, with distinctive white tubers underground.

What weeds tell you

Weeds are opportunists. A thick, correctly mown, correctly watered lawn has very few, because there is nowhere for them to establish. A lawn full of weeds has a growing-conditions problem, and the weed species usually tells you what it is:

• Dollarweed and sedges — too much water, or a drainage problem.
• Spurge and crabgrass — thin turf and exposed soil.
• Moss and algae — shade and permanently wet.

Killing them without changing the conditions means they come back.

Be careful what you spray

St. Augustine is sensitive to several common herbicides, particularly in summer heat. Reading the label for the specific grass type and the temperature limits is not optional — the wrong product on St. Augustine kills the lawn, not the weed.