When to Fertilize St. Augustine in Spring: Don't Feed a Sleeping Lawn
The four signs your St. Augustine is ready for its first real spring feeding, why fertilizing too early backfires, and what to use.
The short version
- You can't feed a lawn into growing. You can only feed a lawn that is growing.
- Wait for all four signs below before the main spring feeding. On the Gulf Coast that's usually late March to early April.
- An optional gentle wake-up feeding can come earlier, but keep it light.
- Pre-emergent comes before any of this, by February 1.
Why early fertilizer backfires
A warm week in February makes everyone want to green up the lawn. But a dormant St. Augustine lawn can't use much fertilizer yet. The nitrogen mostly feeds winter weeds, washes away, or pushes soft top growth before the roots are ready to support it. A late cold snap or a wet spring then turns that tender growth into a fungus problem.
The four signs it's time
- Soil temperature stays around 55°F or warmer for several days in a row. I check it with a long-stem soil thermometer. See how to read soil temperature.
- The lawn is greening on its own, not just a few spots by the house.
- New growth is visible: fresh blades and runners.
- It needs mowing. If you've mowed once or twice for real, it's ready.
Get reminded when it's time
A short email before each key St. Augustine task, plus the printable lawn calendar.
A short email when it's time for the next lawn task. Unsubscribe anytime.
The optional wake-up feeding
The Turf Method program uses a gentle, lower-nitrogen fertilizer (Nitro-Phos Imperial 15-5-10) in late February once soil temps reach about 55°F and the grass starts to show color. Think of it as a nudge, not a full meal. Plenty of people skip it and go straight to the main feeding, and that's fine.
The main spring feeding
Once all four signs line up, apply a slow-release, nitrogen-forward fertilizer that's low in phosphorus, like Nitro-Phos Super Turf 19-4-10, at the label rate. Water it in. Never fertilize a dry, stressed lawn: water first, feed second. Not sure what the numbers mean? See how to read a fertilizer bag.
After that
- One more feeding in early summer if the lawn is healthy and well watered.
- Ease off nitrogen in peak summer heat. It feeds disease and chinch bugs.
- Finish with a low-nitrogen fall fertilizer in early November. See the full calendar.
Everything in my St. Augustine program
The fertilizers, weed killers, fungicides, and tools I actually use on my own lawn, with links to buy.