When to Fertilize Your Lawn by Zone

First, which grass you have

NC State Extension’s rule covers both kinds in one sentence: avoid high nitrogen on cool-season grasses in late spring or summer, and on warm-season grasses in fall or winter. Cool-season grasses — Kentucky bluegrass, fine fescue, perennial ryegrass and tall fescue — grow in spring and fall. Warm-season grasses — Bermudagrass, zoysiagrass, centipedegrass, St. Augustinegrass and bahiagrass — grow in summer. Not sure which you have? See which lawn grasses suit your zone.

Cool-season lawns: mostly fall

Iowa State says a lawn fed only once a year should get it in late October or early November, and a moderately kept lawn in mid-September and late October or early November. Penn State suggests a fertilizer with some slow-release nitrogen at the label rate. University of Illinois Extension links heavy use of fast-release nitrogen in early to mid-fall to snow mold, and recommends slow-release or controlled-release nitrogen instead.

Warm-season lawns: green-up to late summer

1. Wait for full green-up. Clemson’s Bermudagrass calendar puts no nitrogen down while frost is still possible, since new growth followed by a late frost can badly damage the lawn, and feeds in early May once the lawn has fully greened up. It says green-up comes in April on the South Carolina coast and as late as mid-May inland.
2. Feed through summer. Clemson feeds Bermudagrass again in June or July with a fertilizer high in potassium. UGA Extension in Glynn County lists May to August as the best months for Bermuda, St. Augustine and zoysia, and May and July for centipede.
3. Stop two months before frost. Clemson’s last Bermudagrass feeding is before August 15; its centipede calendar gives August 15 for the Upstate and September 1 for the coast. UGA Extension in Dougherty County says not after September. In Florida, UF/IFAS gives September as the last recommended time in North Florida and October in Central Florida, and says grass in parts of South Florida may grow and need fertilizer year-round.
4. Potash only if a soil test says so. Clemson says potassium, not nitrogen, is what helps a lawn through cold, and applies it 4 to 6 weeks before the first expected frost where a soil test shows the soil is low.

Clemson says warm-season grasses such as centipede, St. Augustine, Bermuda and zoysia begin to enter dormancy in late fall and can be injured by fertilizer containing nitrogen applied then; late nitrogen also feeds cool-season weeds and can increase large patch disease.

Spreading it

• Test the soil first. Clemson bases every fertilizer, lime or sulfur application on a soil test, and Penn State says only a soil test tells you how much phosphate and potash a lawn needs.
• Use a spreader. NC State says to apply fertilizer and lime uniformly with a centrifugal (rotary) or drop-type spreader.
• Onto dry grass. Clemson applies granular fertilizer onto dry foliage, to reduce the chance of burn.
• Work out the amount from the bag. Clemson’s rule: to put down 1 pound of nitrogen on 1,000 square feet, divide 100 by the first number on the bag; for half a pound, divide 50.
• Weed-and-feed products. Clemson says many carry a high level of nitrogen that should not go on in fall, and suggests fertilizing to the soil test and managing weeds separately. For any weed or pest product, follow the label and your state’s rules.

Feeding the vegetable garden rather than the lawn? The same bag numbers and the same soil test apply; see tomato fertilizer: what to feed tomatoes and when.

Common mistakes

• A high-nitrogen winterizer on a warm-season lawn. Clemson says it can injure grass entering dormancy.
• Feeding a cool-season lawn in summer. Iowa State says not in June, July or August.
• Feeding a warm-season lawn before green-up. Clemson says a late frost can then badly damage it.
• Feeding tall fescue in spring in the South. Clemson says not after March 15.
• Fast-release nitrogen in early fall. Illinois links it to snow mold.
• Phosphorus and potash by habit. Penn State and Clemson go by a soil test.

Every lawn job by zone

• Cool-Season vs Warm-Season Grass: Which Lawn Grass by Zone
• When to Fertilize Your Lawn by Zone — this page
• When to Overseed Your Lawn by Zone
• When to Aerate Your Lawn by Zone
• When to Stop Mowing: The Last Mow of the Year by Zone
• Winter Lawn Care and Dormant Lawns, by Zone
• Fall Lawn Care by Region: Fertilize, Aerate, Overseed
• Your USDA hardiness zone by ZIP code

Where there is no source here

We found no Texas source on lawn fertilizer timing that we could read: the Texas A&M AgriLife pages we tried did not load. The warm-season dates follow Clemson, written for South Carolina, and UGA and UF/IFAS for Georgia and Florida.