St. Augustine is the dominant lawn grass across Florida, the Gulf Coast, and southern Texas — and it comes with a specific set of challenges that other warm-season grasses don't. Chinch bugs, brown patch fungus, and iron deficiency are near-universal issues in St. Augustine lawns. This guide covers the full care schedule with the pest and disease management this grass requires.
Apply pre-emergent before soil temps hit 55°F to block summer annual weeds. St. Augustine greens up earlier than most warm-season grasses in warm climates — fertilize once the lawn is at least 50% green with a balanced fertilizer. Avoid fertilizers with high levels of phosphorus; St. Augustine rarely needs phosphorus supplementation.
Chinch bugs are the #1 pest threat to St. Augustine lawns. They feed on grass stems and inject a toxin that causes yellowing and death — damage spreads outward from sidewalks, driveways, and the sunniest parts of the lawn. Inspect monthly from April through August. If you see yellowing patches expanding from heat-exposed edges, treat immediately with a pyrethroid insecticide. Early detection makes all the difference.
Fertilize every 6–8 weeks through summer with a slow-release balanced fertilizer. St. Augustine in hot, humid climates is prone to brown patch (large patch) fungal disease — look for circular tan or brown patches with a darker water-soaked border. Prevent it by watering only in the early morning, never in the evening. Apply a preventive systemic fungicide in early summer if you've had brown patch in previous years.
St. Augustine lawns frequently show iron deficiency, especially in alkaline soils or after heavy rains — symptoms are yellowing between leaf veins while veins stay green (interveinal chlorosis). Liquid iron corrects this quickly; results are visible in 3–5 days. Apply it in summer when you can't add more nitrogen without disease risk.
St. Augustine should be mowed at 3–4 inches — significantly higher than Bermuda or Zoysia. Mowing too short exposes the stolons (runners) to sun damage and severely stresses the plant. Remove no more than 1/3 of the blade in a single mow. In summer, mow more frequently rather than cutting lower.
Apply a potassium-heavy fertilizer (no nitrogen) in early fall to harden the grass for winter. Follow with post-emergent herbicide for any active broadleaf weeds. St. Augustine is sensitive to some herbicides — always read labels to confirm compatibility before applying anything to this grass.
St. Augustine care timing varies across Florida, Texas, and the Gulf Coast. Get a 12-month schedule built for your specific zip code, lawn conditions, and issues — including chinch bug and disease alerts.
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