Lawn care calendar for Alabama: when to fertilize and seed

Fertilizer amounts are pounds of nitrogen per 1,000 square feet from the extension tables; the south column follows its South Alabama maintenance calendar. Centipedegrass needs less and is covered in the text.

Which grasses grow where in Alabama

Extension says warm-season grasses make up most Alabama lawns and go dormant in fall and winter. Its mowing table gives bermudagrass 1 to 2 inches, zoysiagrass 1 to 2 inches, St. Augustinegrass 2.5 to 4 inches and tall fescue 2 to 3.5 inches, with the one-third rule for every grass. Centipedegrass is the low-maintenance option at 1 to 1.5 inches, tolerates acidic soil of pH 5.0 to 6.0 and can start from seed.

Tall fescue is a cool-season bunch grass for the north, where the state is at the southern edge of its range. Alabama Extension calls that area the transition zone: tall fescue lawns thin and turn patchy in hot, dry summers and need periodic overseeding, so it is a different lawn from the warm-season grass further south. TifBlair is the one improved centipede variety the extension names for the cold north.

Frost dates from NOAA

Dates are the NOAA 1991-2020 normals for the last spring and first fall 32 F freeze at 50% probability. At Huntsville International Airport the last spring frost averages March 24 and the first fall frost November 8. At Birmingham they are March 21 and November 11, at Montgomery March 13 and November 13, and at Mobile March 3 and November 25.

Counting the days between them gives about 229 frost-free days at Huntsville and 267 at Mobile (our arithmetic). The gap is a little over five weeks.

Spring

The South Alabama calendar starts with a pre-emergent in February, then mowing and an aeration of compacted soil in April, signaled by hard bare ground or moss and algae on the surface. Regular mowing runs every 5 days if clippings stay on the lawn and every 7 if you bag them, at 3.5 to 4 inches for St. Augustinegrass, 1.75 to 2.5 for zoysiagrass and 1 to 2 for bermudagrass.

Feeding follows: 1 pound of nitrogen with a 4-1-2 ratio fertilizer in April and another pound in May. The extension says not to use weed-and-feed, and that feeding warm-season grass too early can cut root mass as it comes out of dormancy. Water weekly if needed, enough to wet the soil 4 to 6 inches, between 6 and 10 a.m.

Summer

The warm-season tables let you choose a standard or maximum plan. Standard is 3 pounds a year for bermudagrass in May, July and August, and 2 pounds for St. Augustinegrass and zoysiagrass in May and July. Maximum plans add one or two feedings, such as June and September on bermudagrass or April and August on St. Augustinegrass. June brings a 4-1-2 feeding, and watching for spittlebugs and chinch bugs.

For tall fescue in the north, the extension keeps the mower at 3 inches in summer, mows once a week, and aims to irrigate a mature lawn once or twice a week. An average lawn uses 1 to 1.5 inches a week in summer when fully established and less in spring and fall, and the extension calls overwatering the biggest mistake homeowners make.

Fall

For warm-season lawns, the extension puts a pre-emergent on in mid-September or early October to stop winter weeds such as burweed, annual bluegrass and chickweed, which grow actively while the lawn is dormant. Skip it if you plan to overseed. Ryegrass overseeding is an option on bermudagrass only, not on St. Augustinegrass or zoysiagrass.

September to October is the best time to seed tall fescue in the north, at 5 to 8 pounds per 1,000 square feet, with a starter fertilizer applied close to seeding. Keep the surface moist, with light watering one to three times a day until seedlings emerge, and start mowing at 2 to 3 inches when they reach about 2.5 inches.

Soil tests and fertilizer rules

I found no Alabama rule that limits phosphorus in home lawn fertilizer. Extension frames it as a soil test question: established lawns need phosphorus only if a test recommends it, and mature lawns do well on ratios such as 1:0:1 or 4:0:3, with a 4-1-2 for the calendar feedings. Soil tests, lime and fertilizer calculators are available through the Auburn University soil testing lab.

Mature lawns need about equal nitrogen and potassium, especially on sandy soil, and lime goes on in December according to the test.

The bag math

Alabama Extension shows the arithmetic: a 50 pound bag of 16-4-8 holds 8 pounds of nitrogen, so each 1 pound of nitrogen takes 6.25 pounds of product. The lawn fertilizer calculator on this site does the same for your bag and square footage.