How to Care for St. Augustine Grass | Lawn Care That Works

St. Augustine grass thrives with mowing at 2.5–4 inches, about 1 inch of weekly water, and fertilizer only during active growth.

For the full breakdown, see our best 16-4-8 Fertilizer For St. Augustine Grass guide.

St. Augustine grass rewards a simple, consistent routine built around three habits: mowing high, watering deeply but rarely, and feeding it only when it’s actively growing. Get those three right and this warm-season grass shrugs off heat, shade, and most pests. Get them wrong—scalping it, sprinkling it daily, or feeding it in winter—and you’ll fight disease and bare patches all season. The steps below follow the guidance of university turf programs, so they’re proven for Southern lawns.

The Right Mowing Height for St. Augustine

Set your mower high. For sunny areas, keep St. Augustine at 2.5–3 inches; in shade, raise it to 3–3.5 inches. Many turf programs, including Texas A&M’s, support 3–4 inches for general care, since taller grass shades its own roots and crowds out weeds.

Two mowing rules keep the lawn healthy:

• Never remove more than one-third of the leaf blade in a single cut. If the grass has grown tall, mow twice a few days apart rather than scalping it down.
• Sharpen the blade regularly. Dull blades shred the leaf tips, leaving a brown, ragged look that invites disease.

Keep the clippings on the lawn. University of Florida extension material notes that clippings return nutrients and organic matter to the soil—no bagging needed.

Watering: Deep, Early, and Not Too Often

Established St. Augustine needs about 1 inch of water per week total, counting rainfall. Delivered as 1–2 deep soakings rather than daily sprinkling, that schedule pushes roots down and keeps the turf resilient. Sandy soil may need slightly more frequent watering, while heavier clay holds moisture longer.

Time your irrigation for the early morning. Florida extension sources call 4–7 a.m. the most efficient window, since the water soaks in before the sun evaporates it and leaves the grass dry before evening—a key defense against fungal disease.

New sod is the exception. Freshly planted St. Augustine needs light, frequent irrigation: multiple short waterings daily for 7–10 days, then about ¼–½ inch once a day for the next week or two. After that, taper to 2–3 times weekly at ¼–½ inch. The lawn is considered fully established around 3–4 weeks after sodding. New lawns should not be fertilized until 30–60 days after planting.

Fertilizing Only During Active Growth

Feed St. Augustine only while it’s actively growing—roughly late spring through summer. LSU AgCenter recommends 1 pound of actual nitrogen per 1,000 square feet in April and June, with an optional additional August application if you want more growth. Stop fertilizing well before fall; feeding late in the season wastes nutrients and can stress the turf going into winter dormancy.

If your soil tests outside the 6.0–7.5 pH range that LSU recommends for St. Augustine, adjust it before adding much fertilizer—off-balance pH locks up nutrients no matter what you spread. And if you’re shopping for the right product, our roundup of the best 16-4-8 fertilizer for St. Augustine grass compares the top options tested for this turf type.

Pests, Disease, and Common Mistakes

St. Augustine’s most frequent troublemakers are chinch bugs, gray leaf spot, take-all root rot, and grub worms. Most of these follow stress: overwatering fuels gray leaf spot; drought-stressed, scalped turf invites chinch bugs. A healthy mowing and watering routine is the first line of defense.

Watch for these three missteps that extension services see most often:

• Scalping. Cutting below 2.5 inches strips the canopy, stresses the stolons, and lets weeds in.
• Frequent shallow watering. Daily light sprinkles train roots to the surface, making the lawn fragile and disease-prone.
• Fertilizing in fall or winter. When growth slows, the plant can’t use the nitrogen, and it leaches away or feeds weeds.

One more thing to know: St. Augustine spreads by above-ground runners and does not overseed well. Bare patches are repaired with sod or plugs, not seed. Dwarf cultivars tolerate a slightly lower cut than standard types, but every variety still does best when mowed high.