# Lawn care calendar for Indiana: when to fertilize and seed > Indiana lawn calendar for bluegrass and tall fescue: Purdue's September and November feeding, seeding dates, mowing heights and NOAA frost dates. Canonical: https://lucernel.com/guides/lawn-care-calendar/indiana Last updated: 2026-10-20 Purdue's turf specialists keep Indiana's lawn calendar short: feed in September and November, seed between mid-August and mid-September, and keep spring nitrogen small. North and south Indiana run about three weeks apart in spring, which Purdue says shows up in crabgrass timing. **September and November are the two best times to fertilize a lawn in Indiana, and seeding peaks August 15 to September 15.** Purdue Extension names September and November as the best fertilizer dates for cool-season lawns, at 1.0 pound of nitrogen per 1,000 square feet in September and 0.5 to 0.75 pound of quick-release nitrogen in early to mid November. Its optimum seeding window is August 15 to September 15 in central Indiana, a week earlier in the north and a week or so later in the south. Crabgrass preventer goes down before germination, which can start April 1 in southern Indiana. (Purdue University Turfgrass Science) | Month | Cool-season lawn (Kentucky bluegrass, tall fescue, fine fescue, ryegrass) | | --- | --- | | January | Dormant | | February | Dormant; plan the year and test the soil | | March | Seed put down in late March germinates in early to mid April | | April | Crabgrass preventer before germination, from about April 1 in the south and three weeks or more later in the north | | May | Keep spring nitrogen small; mow Kentucky bluegrass at 2.0 to 3.5 inches and tall fescue at 3.0 to 4.0 | | June | Little to no nitrogen in summer | | July | Little to no nitrogen in summer | | August | Seeding window opens August 15 in central Indiana (a week earlier in the north) | | September | Seed to September 15; feed 1.0 lb N once highs stay out of the 90s | | October | Fall growth builds density; up to 1 lb N a month is acceptable through early November | | November | Feed 0.5 to 0.75 lb quick-release N in early to mid November, after the last mowing and while green | | December | Dormant; in the south a late November to early December feeding is the equivalent | Seed dates shift a week earlier in northern Indiana and a week or so later in the south. ## Which grasses grow where in Indiana Purdue's extension fertilizer guide describes Indiana lawns as cool-season turf: Kentucky bluegrass, perennial ryegrass, tall fescue and fine fescue, which grow in the cooler weather of spring and fall and slow or go dormant in the heat. Purdue's optimum mowing table, which also covers warm-season grasses, gives these heights in inches: Kentucky bluegrass, fine fescue and perennial ryegrass 2.0 to 3.5; tall fescue 3.0 to 4.0; zoysiagrass 0.5 to 1.0; bermudagrass 0.25 to 1.0. ## Frost dates from NOAA Dates are the NOAA 1991-2020 normals for the last spring and first fall 32 F freeze at 50% probability. Fort Wayne International averages April 24 and October 21. Indianapolis averages April 15 and October 26, and Evansville Regional averages April 4 and October 29. Our arithmetic: Evansville has about 208 days between those dates and Fort Wayne about 180, a gap of 28 days, which matches Purdue's note that crabgrass can germinate three or more weeks later in northern Indiana. ## Spring Crabgrass germinates each spring, as early as April 1 in southern Indiana and three or more weeks later in the north in an average year. Preemergence herbicides have to be down before then, and watered in, which usually means by spring rain. Do not use them on newly seeded lawns or before seeding, except products with siduron. Purdue says to minimize spring fertilization. If a crabgrass product is combined with fertilizer, buy one with most of the nitrogen in slow-release form such as methylene ureas or coated ureas, and avoid products with more than 70 percent of the nitrogen quick-release. Seed put down in late March germinates in early to mid April, which gives it more time to root and compete with summer weeds. ## Summer Purdue's fertilizer guide says to apply less nitrogen in the spring growth flush and then little to none through summer. Cool-season grasses slow or go dormant in the heat. Mowing height is the main summer lever: Purdue's optimum range is 2.0 to 3.5 inches for bluegrass and 3.0 to 4.0 for tall fescue, and mowing above those heights tends to give a less dense, coarser turf. ## Fall Fall is the working season. Purdue says early to mid September is the most important time to fertilize cool-season turf, because it drives new tillers and rhizomes. Apply 1.0 pound of nitrogen per 1,000 square feet any time in September after daytime highs stop reaching the 90s, with a product that mixes quick and slow-release nitrogen. The Purdue extension guide allows up to 1 pound a month from late August through early November. The November application goes near or after the last mowing, while the lawn is still green. Purdue now recommends a lighter rate than it used to, 0.5 to 0.75 pound of quick-release nitrogen in early to mid November, because nitrogen has to be taken up before winter. For seedings, Purdue says that seedings made between August 15 and September 15 should be ready for use by Memorial Day, and that every day you wait after September 15 adds two to four days to maturity. ## Watering new seed and the bag math Keep the upper inch of soil moist with frequent irrigation for the first two or three weeks after seeding, since seedlings are very susceptible to moisture stress. Germination takes 5 to 14 days depending on temperature and species. Purdue's own calculator is one way to convert a target into product; the lawn fertilizer calculator on this site does the same from the nitrogen percentage on the bag and your lawn size, for the 1.0 pound September and 0.5 to 0.75 pound November targets. ## Frequently asked questions ### When should I fertilize my lawn in Indiana? September and November, according to Purdue. About 1.0 pound of nitrogen per 1,000 square feet in September and 0.5 to 0.75 pound of quick-release nitrogen in early to mid November. ### When is the best time to seed grass in Indiana? August 15 to September 15 in central Indiana, a week earlier in the north and a week or so later in the south. ### When should I put down crabgrass preventer in Indiana? Before crabgrass germinates, which can be as early as April 1 in southern Indiana and three or more weeks later in northern Indiana. ### How tall should I mow my Indiana lawn? Purdue's optimum ranges are 2.0 to 3.5 inches for Kentucky bluegrass, fine fescue and perennial ryegrass, and 3.0 to 4.0 inches for tall fescue. ### Can Lawnzo help me follow a Indiana lawn schedule? Lawnzo is a lawn-care planner for iPhone. It builds a season plan from your grass, sun and irrigation, checks each job against the forecast and shows why it keeps, delays or skips it, so the Indiana dates on this page become tasks tied to your own lawn. Its journal keeps products and photos. ## Sources (checked 2026-10-02) - [Purdue Turfgrass Science, Fall Fertilization (September 2011)](https://turf.purdue.edu/fall-fertilization/) - [Purdue Turfgrass Science, Is it too late to apply my last nitrogen fertilization? (November 2014)](https://turf.purdue.edu/is-it-too-late-to-apply-my-last-nitrogen-fertilization/) - [Purdue Turfgrass Science, September is a crucial time to fertilize all cool-season turfs](https://turf.purdue.edu/september-is-a-crucial-time-to-fertilize-all-cool-season-turfs/) - [Purdue Turfgrass Science, Seed Now!](https://turf.purdue.edu/seed-now/) - [Purdue Turfgrass Science, Start seeding cool-season turf now (August 2014)](https://turf.purdue.edu/start-seeding-cool-season-turf-now/) - [Purdue Turfgrass Science, Seed early in the spring for better success](https://turf.purdue.edu/seed-early-in-the-spring-for-better-success/) - [Purdue Turfgrass Science, How to select a crabgrass preventer from the store](https://turf.purdue.edu/how-to-select-a-crabgrass-preventer-from-the-store-homeowners/) - [Purdue Turfgrass Science, Turf 101: Optimum mowing heights for turf](https://turf.purdue.edu/turf-101-optimum-mowing-heights-for-turf/) - [Purdue Turfgrass Science, Watering newly seeded areas](https://turf.purdue.edu/watering-newly-seeded-areas/) - [Purdue Extension, AY-22-W: Fertilizing Established Cool-season Lawns](https://www.extension.purdue.edu/extmedia/AY/AY-22-W.pdf) - [NOAA NCEI 1991-2020 normals: frost dates for Fort Wayne International Airport, Indianapolis, Evansville Regional Airport (API query)](https://www.ncei.noaa.gov/access/services/data/v1?dataset=normals-annualseasonal-1991-2020&stations=USW00014827,USW00093819,USW00093817&dataTypes=ANN-TMIN-PRBLST-T32FP50,ANN-TMIN-PRBFST-T32FP50&format=json) - [NOAA NCEI, U.S. Climate Normals 1991-2020 (product page)](https://www.ncei.noaa.gov/products/land-based-station/us-climate-normals) - [NOAA NCEI, station inventory (GHCN-Daily station list)](https://www.ncei.noaa.gov/pub/data/ghcn/daily/ghcnd-stations.txt)