In Pinellas County, fertilize St. Augustine in early April, again in mid-to-late May, then a final feeding in early October. If you live anywhere else in the state, the calendar is different. The fertilizer blackout from June 1 through September 30 cuts the typical Florida feeding season nearly in half here, and the generic advice you find online will get your timing wrong.
This schedule follows University of Florida IFAS turfgrass guidance and the Pinellas County fertilizer ordinance, both cited below. For month-by-month mowing, watering, and pest tasks, pair this with our St. Augustine maintenance calendar.
The Pinellas fertilizer blackout changes everything
From June 1 to September 30, Pinellas County prohibits the sale and use of lawn or landscape fertilizer containing nitrogen or phosphorus. That’s county law, not a suggestion, and St. Petersburg enforces it along with every other city in the county. The county adopted the rule to keep nutrients out of storm drains and waterways during the rainy season, when runoff feeds algae blooms and red tide.
That leaves you roughly seven legal feeding months, October through May, while the grass does most of its growing during the four months you cannot feed it. Your fertilizer plan has to work around that gap.
For the full legal picture, including fines, retailer rules, and exemptions, read our guide to the Pinellas County fertilizer ban. The points that shape your schedule, straight from the county:
- No nitrogen or phosphorus fertilizer applied or sold June 1 through September 30 (Pinellas County Fertilizer & Landscape Information)
- Maximum 4 pounds of nitrogen per 1,000 square feet per year, year-round
- Granular nitrogen fertilizer must be at least 50 percent slow-release
- Phosphorus requires a soil test showing deficiency before you can apply it at all
- A 10-foot fertilizer-free zone applies around any seawall or body of water
- Never fertilize when heavy rain is in the forecast
The Pinellas St. Augustine fertilizer schedule
UF/IFAS recommends the first fertilizer application of the year in early April for central Florida, which includes Pinellas County (St. Augustinegrass for Florida Lawns, ENH5/LH010). Central Florida St. Augustine needs 2 to 5 pounds of nitrogen per 1,000 square feet per year, but the county caps you at 4, so split it across the legal windows like this.
Early April: the wake-up feeding
Apply once the grass is fully greened up and actively growing, usually the first half of April in St. Pete. This is your biggest application of the year. Use up to 1 pound of nitrogen per 1,000 square feet, and make sure the granular product is at least 50 percent slow-release nitrogen so it feeds for 6 to 8 weeks instead of burning off in a week.
Do not rush this in March. IFAS warns against fertilizing too early, before the root system is fully active, because the grass cannot take up the nutrients and the excess washes away.
Mid-to-late May: the pre-blackout feeding
Your second application goes down two to three weeks before the June 1 blackout starts. Target mid-May, and do not push it to the last weekend of the month. If a tropical system or heavy rain is forecast, the county’s weather restrictions can shut you down early.
Use 0.5 to 1 pound of slow-release nitrogen per 1,000 square feet. Because this feeding has to carry the lawn through four months of no fertilizer, the slow-release content matters more here than anywhere. A quality coated product keeps trickling nitrogen into the root zone well into June.
June through September: no nitrogen, but not no care
During the blackout you cannot apply nitrogen or phosphorus, but iron and micronutrient products are still allowed. A chelated iron application in July or August keeps the lawn dark green without pushing growth, and it does not violate the ordinance. Potassium-only products (0-0-x formulas) are also legal and help the grass handle summer stress, chinch bug pressure, and disease.
This is also when mowing height does most of the work. Keep St. Augustine at 3.5 to 4 inches all summer. Scalping a hungry lawn in July is how bare patches start.
Early October: the recovery feeding
October 1 is the first legal day, and your lawn needs it. Four months of heat, rain, chinch bugs, and zero nitrogen leave St. Augustine thin and pale by fall. Apply 0.5 to 1 pound of slow-release nitrogen per 1,000 square feet in the first two weeks of October.
Do not fertilize past mid-November. IFAS guidance is to avoid feeding after growth slows, because late nitrogen pushes tender growth that winter cold snaps can damage.
Optional: late winter touch-up
If your lawn stays green and growing through winter, a light application of 0.5 pound per 1,000 square feet in February or March is legal and safe. Skip it if the lawn went tan and dormant. Feeding dormant grass feeds weeds instead.
Why generic advice fails in Pinellas
National lawn care sites say “fertilize in spring and fall” or “feed every 6 to 8 weeks during the growing season.” Follow that here and you will either break the law or starve the lawn. Three things make Pinellas different.
First, the growing season and the legal feeding season barely overlap. St. Augustine grows hardest June through September, exactly when fertilizer is banned. Your May application has to carry the lawn through the ban, which is why slow-release content and timing matter more than the brand on the bag.
Second, the annual cap bites. Generic schedules call for 4 to 6 pounds of nitrogen per year on St. Augustine. Pinellas caps you at 4, so you have to get more out of fewer pounds. Mulching clippings back into the lawn returns a meaningful share of the nitrogen the grass needs, and it is free.
Third, phosphorus is off the table by default. Balanced fertilizers like 10-10-10 are effectively illegal without a soil test proving deficiency. Shop for lawn fertilizers with a zero middle number, something like 15-0-15, which is what most Florida-specific products are anyway.
Choosing the right fertilizer
The county rules and IFAS guidance point to the same product profile:
- Zero phosphorus unless a soil test says otherwise
- At least 50 percent slow-release nitrogen (look for “polymer coated,” “sulfur coated,” or “controlled release” on the label)
- No more than 1 pound of nitrogen per 1,000 square feet per application
- Iron or micronutrients included if you can find them
Apply no more than four pounds of nitrogen per 1,000 square feet across the whole year. Sweep granules off driveways and sidewalks back onto the lawn, stay 10 feet away from seawalls and water, and check the forecast before you spread.
If you’d rather have a crew handle the timing and product selection, our fertilization service is built around Pinellas County’s legal windows.
FAQ: when to fertilize St. Augustine grass
What month do you fertilize St. Augustine grass in Florida?
In Pinellas County, fertilize in early April, mid-to-late May, and early October. UF/IFAS sets the first application at early April for central Florida. The county fertilizer ban then closes the window from June 1 through September 30, so the last feeding waits until October.
Can I fertilize my lawn in the summer in Florida?
Statewide, yes, but not in Pinellas County. The county prohibits applying or selling fertilizer with nitrogen or phosphorus from June 1 to September 30. Iron and micronutrient products without nitrogen or phosphorus remain legal all summer.
How often should you fertilize St. Augustine grass?
UF/IFAS recommends 2 to 6 applications per year depending on region, totaling 2 to 5 pounds of nitrogen per 1,000 square feet in central Florida. In Pinellas, the blackout and the 4-pound annual cap compress that to two or three well-timed applications.
What happens if you fertilize during the Pinellas blackout?
You are violating the county fertilizer ordinance, which applies countywide including St. Petersburg. Enforcement can mean fines, and the environmental cost is real: summer rains wash nitrogen straight into storm drains, feeding the algae blooms the ordinance exists to prevent.
Should I fertilize St. Augustine before or after rain?
Neither, if heavy rain is coming. Pinellas County warns against fertilizing before heavy rain because the product washes off the lawn and into the storm system. Apply to a dry lawn when no storms are forecast, then water it in lightly yourself.
What is the best fertilizer for St. Augustine grass in Florida?
A slow-release, zero-phosphorus lawn fertilizer such as a 15-0-15, with at least 50 percent of the nitrogen in coated or controlled-release form. That profile matches both the Pinellas ordinance and UF/IFAS recommendations.
Get the timing right without the homework
Fertilizing St. Augustine grass in Florida is a timing game, and Pinellas County’s rules make the calendar tighter than anywhere else in the state. Miss the May window and the lawn goes four months without food. Feed too late in fall and a cold snap punishes that new growth.
If you would rather hand the schedule to a crew that already knows the ordinance, we time every application to the legal windows and use county-compliant slow-release products. See the cost of professional lawn care in St. Pete, or get a free estimate from St. Pete Lawn Care and call (727) 218-4044. We will put your lawn on the right feeding schedule this week.