Lawn care calendar for Virginia: when to fertilize and seed

Western Virginia runs about three months shorter than the southeast, so shift every row accordingly.

Which grasses grow where in Virginia

Virginia Tech lists Kentucky bluegrass, tall fescue, perennial ryegrass and fine-leaf fescues as the predominant cool-season lawn grasses, with bermudagrass, zoysiagrass and centipedegrass as the warm-season choices. Seeding rates per 1,000 square feet for cool-season grasses are 2 to 3 pounds of Kentucky bluegrass, 6 to 8 of tall fescue, 4 to 6 of perennial ryegrass and 3 to 5 of fine-leaf fescue. Mature zoysia, centipedegrass and fine fescue need less nitrogen than bluegrass, tall fescue, ryegrass or bermudagrass.

Warm-season grasses use water more efficiently than cool-season ones. Virginia Tech also discourages overseeding any warm-season lawn in winter except bermudagrass.

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 Roanoke the average last spring frost is April 3 and the average first fall frost is November 1. Richmond is April 3 and November 4, Washington Dulles is April 15 and October 24, and Norfolk is March 17 and November 23.

Our arithmetic: Norfolk has about 251 days between its two dates and Dulles about 192, a gap of 59 days.

Spring

Cool-season lawns do best when most nitrogen goes on in fall, and Virginia Tech advises avoiding large spring nitrogen applications, which feed top growth into the summer stress period. A spring pre-emergent herbicide is aimed at summer annual weeds such as crabgrass, goosegrass and foxtail. Check the label before seeding, because a pre-emergent can block the seed you want.

Warm-season lawns can be fed starting April 1. The window runs through August 15, and heavy late summer or early fall nitrogen on bermudagrass makes the turf lush and more prone to winter injury.

Summer

Most turf needs about 1 inch of water a week from rain or irrigation. Virginia soils soak slowly, so one inch rarely goes in at once; a deep, infrequent soak that wets the root zone to about 4 inches beats frequent light watering. New seeded or sodded lawns need more frequent water for the first three to four weeks. Overwatering brings summer fungus and more mowing.

Raise the mower on cool-season lawns before summer stress arrives, because taller grass roots deeper and shades the soil. Never remove more than a third of the blade, and keep traffic off drought-stressed turf.

Fall

Warm days and cool nights give tall fescue, bluegrass, ryegrass and fine fescue their best seed germination. For new plantings, till 4 to 6 inches deep. For overseeding, a few passes with a core aerator or a vertical mower give seed contact, since seed spread over untouched turf mostly feeds birds. Irrigate lightly and often until germination.

Virginia Tech's cool-season calendar suggests up to 0.7 pound of water-soluble nitrogen per 1,000 square feet every three to four weeks during the fall window, or controlled-release products up to 0.9 pound per active growing month. For tall fescue, an optimal height is 2 inches, so start mowing a new lawn as soon as it reaches 3.

What Virginia's rules cover

Virginia's lawn fertilizer rules, in Code of Virginia section 3.2-3602.1 and 2VAC5-405, target people who apply fertilizer to nonagricultural land for hire, plus state agencies and localities. They must use a certified fertilizer applicator, follow the state's nutrient management standards for rates, times and methods, and keep records. Applicators who treat more than 50 acres a year file an annual report by February 1. Compliant contractors are exempt from local fertilizer ordinances.

For homeowners, the Code lets the Department of Agriculture publish best practices instead of setting dates, and since December 31, 2013 it has been illegal to sell de-icing products that contain urea, nitrogen or phosphorus. The lawn fertilizer calculator on this site helps you pick a rate in line with those Virginia Tech figures.