What is yellow foxtail?

Yellow foxtail is a summer annual grass that sprouts after the soil warms in late spring and dies at the first frost. Yellow foxtail identification is helpful because it’s often lumped in with crabgrass, and while the control approach is similar, it’s not exactly the same.

It’s a common weed in farm fields and gardens, and it shows up in lawns where turf is thin, newly seeded or recently disturbed. It doesn’t spread by roots, only by seed, so a few years of good prevention can make a big difference. Seeds dropped in late summer mostly sprout the following spring, so stopping seed this year pays off next year.

The bristly seedheads are what most people notice. They pop up in midsummer and turn yellow-orange as they mature.

Yellow foxtail identification: what to look for

Check these features:

• Leaves: flat, pale to medium green blades about a quarter to half an inch wide, often with a slight twist. Look for long, sparse hairs near the base of the upper leaf surface; this is the main way to tell it from green foxtail.
• Sheath and ligule: the leaf sheath is smooth, and the ligule, where the blade meets the stem, is a fringe of short hairs.
• Stems: often reddish-purple at the base, growing in clumps.
• Seedheads: dense, upright, cylinder-shaped and bristly, 2 to 4 inches long, turning yellow to orange-tan as they mature in late summer.
• Seeds: small, rounded and ridged, dropping from the heads in late summer and fall.

Where it grows in Pennsylvania

Yellow foxtail grows statewide in thin or newly seeded lawns, garden beds, field edges, roadsides and any disturbed soil. It loves full sun and bare ground, and it handles a range of soil types.

In lawns, it’s most common where turf has thinned out from drought, grubs or wear, along hot sidewalk and driveway edges and in spots that were reseeded in spring. Seeds can hide in topsoil from farm fields, so it often appears after new soil is brought in.

Seeds keep sprouting from late spring into early or mid summer, starting once the soil warms to about 65°F. That’s why a lawn can look clean in May and still fill with foxtail by August if the turf is thin.

Yellow foxtail look-alikes

Several summer annual grasses look similar:

• Green foxtail is the closest look-alike. Its upper leaf blade is smooth without the long hairs near the base, its sheath has fine hairs on the edges and its seedhead stays greener and softer.
• Giant foxtail is taller with short hairs all over the upper leaf surface and a longer, nodding seedhead.
• Large crabgrass has hairy leaves and sheaths, a papery ligule and finger-like seedheads.
• Barnyardgrass has no ligule at all and a coarser, branched seedhead.

All are summer annuals, so prevention works the same way.

How to get rid of yellow foxtail

Hand and mechanical. For a few plants in a lawn or bed, pulling or digging them out works well. Do it before the seedheads mature in late summer. In gardens, shallow hoeing on a dry day kills young seedlings. Bag plants that already have seedheads rather than leaving them on the ground. Mowing won’t kill it, but regular mowing at 3 to 3.5 inches keeps seedheads from forming and helps the lawn compete.

Cultural. Thick turf is the best defense. Fertilize mainly in fall based on a soil test, water deeply during dry spells and overseed thin areas in late summer or early fall, when foxtail isn’t germinating. In beds, mulch 2 to 3 inches deep. If you bring in topsoil, ask where it came from.

Chemical. Penn State Extension lists preemergence herbicides such as prodiamine, pendimethalin and dithiopyr, applied in spring before soil temperatures reach about 65°F. In central PA, that’s usually April to early May. Preemergence products also stop grass seed from sprouting, so don’t use them where you plan to overseed. For plants already up, extension recommends postemergence products containing fenoxaprop, quinclorac or topramezone, applied to young plants in early summer.

Read and follow the product label, because the label is the law, and make sure it’s labeled for your type of grass and site. Applying herbicide for hire in Pennsylvania requires a PA Department of Agriculture pesticide applicator certification, so whole-lawn programs should go to a licensed lawn-care company.

Keeping it from coming back

Because yellow foxtail spreads only by seed, the long-term fix is never letting it go to seed and keeping your lawn too thick for seeds to sprout. Mow high, fertilize in fall and overseed thin spots.

In beds, keep a good layer of mulch. If foxtail keeps coming up in patio joints or along walkways, sweep out the joints and refill with polymeric sand.

A couple of seasons of good prevention can dramatically reduce how much you see.

Questions we get about yellow foxtail

Similar weeds

Green FoxtailSetaria viridisGiant FoxtailSetaria faberiLarge CrabgrassDigitaria sanguinalis