You can buy the best fertilizer on the shelf and still waste it if you spread it at the wrong time. Grass only uses what it can take up while it is growing, and Central Texas grasses spend a good chunk of the year either ramping up or shutting down. Get the timing right and the same bag of fertilizer does a lot more work. Here is how the year breaks down for a San Antonio lawn.
Quick answer
Feed warm-season grasses like St. Augustine and Bermuda only when they are actively growing. In Central Texas that means the first application about three weeks after the grass fully greens up in spring (usually April), again in early summer, and a final feeding in early fall. Skip fertilizer in winter while the grass is dormant. Soil temperature, not the calendar, is the real trigger.
Want it handled for you?
Tired of guessing at fertilizer timing? Schedule a prescription fertilization program with Prescription Lawn Services and we'll feed your San Antonio lawn the right blend at the right intervals all season.
See how our fertilization program fits into your prescription plan.
Wait Until the Grass Is Actually Growing
Most lawns in San Antonio are warm-season grasses: St. Augustine, Bermuda, or Zoysia. These go dormant and brown in winter, then green back up as the soil warms in spring. Fertilizing while the grass is still dormant or just waking up feeds weeds more than turf, because the grass roots aren't ready to absorb the nutrients.
Texas A&M AgriLife advises holding the first application until about three weeks after the lawn has completely greened up, which in Central Texas usually lands in April. A late frost can set growth back, so watch the grass rather than the calendar. If it is still patchy and pale, it isn't ready to eat.
A Realistic Central Texas Schedule
A simple, effective program for most home lawns is three feedings spread across the growing season. That gives the grass steady nutrition without pushing it so hard that it outgrows what the roots and water can support.
Bermuda is hungrier and can take a fourth feeding if it is in full sun and mowed often. St. Augustine generally does well on three. The point is to match the feeding to how fast the grass is growing, not to dump everything in one heavy spring application.
- Early spring (about April): first feeding, three weeks after full green-up
- Early summer (June): second feeding to carry the lawn through the heat
- Early fall (September to early October): last feeding before dormancy
- Winter: no fertilizer while the grass is dormant
What Nitrogen, Phosphorus, and Potassium Do
The three numbers on a fertilizer bag are nitrogen, phosphorus, and potassium, in that order. Nitrogen drives the green, leafy growth you see, and it is the nutrient lawns use up fastest. Phosphorus supports root development and is most useful when establishing new grass. Potassium helps the plant handle stress: heat, drought, and disease.
Many established Central Texas lawns already have plenty of phosphorus in the soil, so a high-middle-number fertilizer is often unnecessary and, in some cases, restricted to protect waterways. A soil test tells you what your yard actually needs instead of guessing. Without one, a fertilizer that is mostly nitrogen with some potassium is a safe bet for an established lawn.
The Fall Feeding Is the One People Skip
It is tempting to stop thinking about the lawn once summer ends, but the early-fall feeding is one of the most valuable of the year. It helps the grass store energy before dormancy, which means a stronger, faster green-up next spring and better resistance to winter weeds.
Don't push it too late, though. Feeding nitrogen-heavy fertilizer once the grass is sliding into dormancy can encourage tender growth that gets nipped by the first cold snap, and it can feed cool-season weeds and large patch fungus. Early fall is the window: roughly September into the first part of October in our area.
Watering and Mowing Make the Fertilizer Work
Fertilizer needs water to reach the roots, so plan to apply it before a rain or water it in afterward with about a quarter inch. Don't fertilize a drought-stressed, crispy lawn and expect results, because the grass can't use it.
Mowing height matters too. Cutting St. Augustine too short stresses it and undoes the benefit of feeding it. Keep the blade high, leave the clippings on the lawn (they recycle nitrogen back into the soil), and the fertilizer you do apply stretches further.