St. Augustine Grass Spring Care (The Complete Guide)

If you live anywhere from Florida to Texas, there’s a good chance you’re looking at St. Augustine grass right now. About 70 percent of Florida lawns are St. Augustine. It handles shade better than Bermuda, tolerates salt spray near the coast, and when it’s healthy, it forms a thick, blue-green carpet that looks like a million bucks.

But St. Augustine is also the neediest warm-season grass out there. It drinks more water than Bermuda or Zoysia. It’s pickier about mowing height. And when something goes wrong in spring, it lets you know fast.

Spring is make-or-break season for your St. Augustine lawn. Get the timing right on mowing, watering, and fertilizing, and you’ll have the best-looking yard on the block by June. Here’s exactly what to do and when to do it.

When Does St. Augustine Wake Up in Spring?

St. Augustine wakes up gradually as soil temperatures climb above 55 to 60 degrees. In South Florida, that’s as early as late February. Central Florida and the Gulf Coast, mid-March. North Florida, the Carolinas, and Texas usually see green-up between mid-April and early May.

Signs your St. Augustine is waking up:

• New green runners spreading from the stolons
• Green blades pushing up through dormant thatch
• Growth speeding up enough to notice between mowings

Don’t rush things. Wait until you’ve had to mow at least twice before starting your spring care routine. That tells you the grass is awake and ready to take up nutrients.

Spring Mowing Guide for St. Augustine

Mowing height matters more for St. Augustine than almost any other grass type. This is a tall grass. It wants to be tall. Cutting it too short is one of the fastest ways to kill it.

Set your mower to 3.5 to 4 inches. If your lawn gets partial shade, go with 4 inches. The taller blades give the grass more surface area to capture sunlight, which is critical in shady spots.

Here’s what happens when you cut St. Augustine too short:

• The root system weakens
• Weeds move in because the thin canopy lets sunlight hit the soil
• The grass stresses out and turns yellow or brown
• You end up with bare spots that cost money to fix

Never remove more than one-third of the blade height in a single mowing. Mow every 5 to 7 days once spring growth kicks in. Keep your blades sharp — dull blades tear the grass and invite disease.

One more thing. Mower damage is one of the top reasons sprinkler heads break. When you’re mowing at 3.5 to 4 inches, those sprinkler heads at ground level are easy to miss. A mower wheel or deck can crack a head and you won’t notice until that zone stops watering properly.

Watering Your St. Augustine in Spring

St. Augustine is the thirstiest warm-season grass. Bermuda needs about 1 inch per week. Zoysia can get by on three-quarters. St. Augustine needs 1 to 1.5 inches per week, and during hot, dry stretches, even more. That means your irrigation system has to be working perfectly. Every head. Every zone.

When to start watering: Don’t irrigate the moment you see green. Watch for drought stress signs: dull blue-gray color, footprints that stay visible, leaf blades that curl inward. When you see those, turn the system on.

How often: Two to three times per week. Deep, infrequent watering beats shallow daily watering. You want water to soak 6 to 8 inches so roots grow deep.

Best time of day: Between 4 AM and 6 AM. Early morning minimizes evaporation and lets blades dry before nightfall. Afternoon watering wastes 30 to 50 percent to evaporation. Night watering invites fungal disease.

Check your coverage: Place empty tuna cans around a zone, run it for 15 minutes, and measure the water depth. If one can has half an inch and another has nothing, you’ve got a problem — usually a head that’s broken, misaligned, or sinking below grade.

Spring Fertilizer Schedule

When to apply: Wait until your lawn has needed mowing at least twice. In Central Florida, that’s mid to late April. North Florida and Gulf Coast states, late April to mid-May.

What to use: A 16-4-8 fertilizer works well. Apply 1 pound of actual nitrogen per 1,000 square feet (about 6.25 pounds of 16-4-8 product). If your lawn looks yellow but you don’t want heavy nitrogen yet, try an iron-only supplement to green things up.

What NOT to do:

• Don’t fertilize before the grass is actively growing — nutrients wash away
• Don’t use weed-and-feed without checking the label. Some herbicides damage St. Augustine.
• Don’t over-fertilize. Too much nitrogen means more mowing, more water demand, and more disease risk.

Common Spring Problems and How to Fix Them

Brown Patch (Large Patch Fungus)

Brown patch shows up as circular patches where blades turn brown at the base. Pull on a blade — if it slides out with no resistance, that’s brown patch. It thrives when nights drop below 70 and days hit 80 (November through April in Florida).

Fix it: Reduce watering frequency, stop evening watering, and hold off on fertilizer until it clears. Nitrogen fuels fungal growth.

Chinch Bugs

Chinch bugs suck sap from grass blades, creating irregular yellow patches that turn brown and die — usually near sidewalks and driveways where it’s hot and dry. They start feeding in April and May, peaking June through September.

Test: Push a bottomless coffee can 3 inches into the soil at the damage edge, fill with water, wait 10 minutes. Tiny black insects with white markings floating up means chinch bugs. Treat with bifenthrin or imidacloprid at the first sign of damage.

Dry Spots and Dead Patches

Not every brown spot is disease or pests. Sometimes it’s a section that isn’t getting enough water.

• A sprinkler head that’s broken and not popping up
• A head knocked out of alignment by a mower or trimmer
• A head that’s sunk below the grass line
• Grass growing over a head, blocking the spray pattern

A broken sprinkler head creates a dry zone that slowly turns yellow. With St. Augustine, dead patches don’t fill in from seed like Bermuda does. A dead patch either grows back slowly from the edges or gets resodded.

The cost: A single resod repair runs $200 or more. That’s a lot of money for something a $6.50 sprinkler head protector could have prevented.

The One Thing Most Homeowners Overlook

You can nail the mowing height, get the fertilizer timing perfect, and water at exactly the right time. But if your sprinkler heads aren’t working properly, none of it matters.

Because St. Augustine needs more water than Bermuda or Zoysia, every single sprinkler head has to perform. One broken head means one dry zone. One dry zone means one dead patch. And one dead patch means $200 or more to resod.

The math is simple. A 10-pack of Sprinkler-Guard protectors costs $64.99. A single resod repair costs $200 or more. Protecting your heads costs less than fixing one dead patch.

Sprinkler-Guard protectors keep your heads visible, protected from mower and trimmer strikes, and prevent grass from growing over them. They install in 30 seconds per head. No tools needed. Made from flexible ABS plastic that won’t crack like concrete donuts.

Made in the USA by a veteran-owned company in Sarasota, Florida. The same state where St. Augustine is king. Check them out at Sprinkler-Guard.com.

Frequently Asked Questions

When should I start spring care for my St. Augustine lawn?

Wait until soil temperatures are consistently above 55 to 60 degrees and you see visible green growth. In most of Florida, that’s mid-March. Gulf Coast and Texas, mid-April to early May. Don’t fertilize until you’ve mowed at least twice.

How high should I mow St. Augustine grass?

Set your mower to 3.5 to 4 inches. Go with 4 inches in partial shade. Never remove more than one-third of the blade height in a single mowing.

How much water does St. Augustine need per week?

St. Augustine needs 1 to 1.5 inches per week. Water two to three times per week, early morning between 4 AM and 6 AM. Deep, infrequent watering is better than shallow daily watering.

Written by Ken Kwiatkowski, founder of Sprinkler-Guard. 20+ years protecting lawns and irrigation systems across Florida. Veteran-owned, Made in the USA.

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Sprinkler-Guard. Made in the USA. Veteran-owned. Patented.