Neon Green St. Augustine in South Texas: Soil Test Is the Only Answer

South Texas homeowner: ¼ acre St. Augustine turning neon green/yellow for 3–4 years. Tried iron, fungicides, nothing works. Thick, healthy otherwise. Trees present. Asks for diagnosis.

The Cake Analogy

Growing grass without soil test = baking cake without checking ingredients or oven temp. You wouldn't add flour if you have it; don't add iron if soil has it. You MUST know pH (oven temp) and nutrients (ingredients).

Why Guessing Fails

• Iron deficiency rare; high pH makes iron unavailable—adding iron doesn't help.
• Overwatering, insects, pH all cause yellowing.
• "Light green" ≠ "neon yellow"—distinguish Bahiagrass trait from deficiency.

Mandatory: Soil Test

Texas A&M Extension: tce.tamu.edu → click your county. Modest fee. Worth its weight in gold.

Critical Data Needed

Sun exposure: Dawn to dusk, how many hours full sun, light shade, full shade? Watch today and report.

Next Steps

Soil test reveals exact deficiencies/excesses. Then targeted correction. No more shotgun remedies.