Reference data · updated for 2026
Pre-Emergent Timing by State
Pre-emergent herbicide is the cheapest weed control there is, and the easiest to waste: applied two weeks late it does nothing at all. The right date is set by soil temperature, not the calendar — which is why the window sweeps roughly ten weeks from the Sun Belt to the Great Lakes.
The dates below are the researched windows. For the reading behind them today, the soil temperature tool looks up the modelled soil temperature for your own town and reads it against the same published trigger.
The ten-week sweep, at a glance
- Warm-season (southern lawns)
- Cool-season (northern lawns)
- Transition zone (both grown)
- Separate fall window
Bars are month-level summaries of each state's researched window — exact dates, in-state variation and soil-temperature triggers are in the table below. Free to reuse with a link back to this page.
Spring application windows, south to north
Swipe the table sideways
| State | Typical window & trigger | Dominant turf |
|---|---|---|
| California | Mid-January (Los Angeles/San Diego) to late February (Sacramento/Bay Area) — before the last winter rains water it in for free | Tall Fescue |
| Alabama | Late February on the coast to mid-March in north Alabama — the earliest pre-emergent window of any state we cover | Centipede |
| Arizona | Mid-February for summer weeds, and again late September for winter weeds germinating in the overseed | Bermuda |
| Florida | Early February (Orlando/Tampa) to early March (Panhandle); South FL applies year-round for tropical weeds | St. Augustine |
| Georgia | Mid-February (Savannah/South GA) to early March (Metro Atlanta), with a second application about eight weeks later — the state is long enough north to south that one date cannot serve it | Bermuda |
| Hawaii | There is no single spring flush to time against — warm-season weeds germinate through much of the year, so pre-emergent here is a repeated programme on label intervals rather than a February or March decision | Bermuda |
| Louisiana | Late February to mid-March, before soil warms past 55°F — the earliest window of any state we cover | St. Augustine |
| Mississippi | Late February on the coast to mid-March in the north | Bermuda |
| Nevada | February in Las Vegas to April in the northern high desert | Tall Fescue |
| New Mexico | Crabgrass and summer annual pre-emergent as soil holds 55°F at 2 inches — February to early March in the southern valleys, April to May in the north. The state spans two months on this decision | Bermuda |
| Oregon | Late February to March west of the Cascades — the earliest cool-season window anywhere, because the valley barely stops growing | Perennial Ryegrass |
| Texas | Mid-February (Houston/San Antonio) to mid-March (Dallas/Panhandle), soil temps 55°F for crabgrass | Bermuda |
| Arkansas | Early March in the south to early April in the Ozarks at soil 55°F | Bermuda |
| Delaware | Crabgrass pre-emergent as soil holds 55°F at 2 inches — typically mid-March in Sussex and late March to early April in New Castle County, with a second application six to nine weeks later because one pass does not cover a Delaware season | Tall Fescue |
| Illinois | Late March at the Ohio River confluence to late April in Chicagoland — the widest single-state spread in the Midwest, and the reason calendar-based advice fails here | Kentucky Bluegrass |
| Kansas | Crabgrass pre-emergent as soil holds 55°F at 2 inches — typically late March to mid-April moving northwest, with a second application six to eight weeks later in the wetter east | Tall Fescue |
| Kentucky | Mid-March in the Jackson Purchase to early April in the mountains at soil 55°F — and over Inner Bluegrass karst the barrier is worth splitting into two applications, because the ground drains faster than the label assumes | Turf-Type Tall Fescue |
| Maryland | Mid-March on the Eastern Shore to mid-April in the mountains — forsythia bloom is the traditional Maryland signal (soil 55°F) | Turf-Type Tall Fescue |
| Missouri | Late March in the Bootheel to mid-April along the Iowa line — soil 55°F moves south to north across about three weeks | Turf-Type Tall Fescue |
| North Carolina | Early to mid-March in the Piedmont, when soil temps approach 55°F — earlier along the coast | Tall Fescue |
| Ohio | Late March along the Ohio River to late April in the Lake Erie snow belt at soil 55°F — a month of spread across one state | Kentucky Bluegrass |
| Oklahoma | Early March in the south to early April in the panhandle at soil 55°F; on western sand, split the rate rather than trusting one pass to hold | Bermuda |
| South Carolina | Early March on the coast to late March in the Upstate, before soil warms past 55°F | Centipedegrass |
| Tennessee | Early March in Memphis to late March in Knoxville — soil 55°F sweeps west to east | Tall Fescue |
| Utah | Late March to mid-April along the Wasatch Front at soil 55°F | Kentucky Bluegrass |
| Virginia | Early March (Hampton Roads/Tidewater) to late March/early April (Northern VA/Richmond), as soil reaches 55°F | Tall Fescue |
| West Virginia | Crabgrass pre-emergent as soil holds 55°F at 2 inches — typically late March to early April in the valleys, into late April at elevation, with a second application six to nine weeks later | Tall Fescue |
| Colorado | Late April to early May as soil reaches 55°F | Kentucky Bluegrass |
| Connecticut | Crabgrass pre-emergent as soil holds 55°F at 2 inches — mid-April along the shoreline, into early May in the hills; forsythia dropping its blooms is the local cue | Kentucky Bluegrass |
| Idaho | Crabgrass pre-emergent as soil holds 55°F at 2 inches — usually April in the Treasure Valley, May in the north and at elevation. Cool-season turf here grows fastest when soil sits at 55 to 65°F, which is the same signal | Kentucky Bluegrass |
| Indiana | April, on soil temperature — and Purdue's note is that any nitrogen in a pre-emergent product should be slow-release, capped at 0.75 lb per 1,000 sq ft | Kentucky Bluegrass |
| Iowa | Mid-April to early May at soil 55°F — a narrow, late window compared with the states south of here | Kentucky Bluegrass |
| Massachusetts | Mid-April on the coast to early May in the Berkshires at soil 55°F — forsythia is the working signal here | Kentucky Bluegrass |
| Michigan | Late April (Metro Detroit/South) to mid-May (Up North), as soil reaches 55°F | Kentucky Bluegrass |
| Nebraska | Crabgrass pre-emergent as soil holds 55°F at 2 inches — usually late April in the south-east, into mid-May in the north and west | Kentucky Bluegrass |
| New Hampshire | Crabgrass pre-emergent as soil holds 55°F at 2 inches — late April to early May on the Seacoast, and up to three weeks later in the north; crabgrass pressure itself falls off with elevation | Kentucky Bluegrass |
| New Jersey | Mid-April in the south to early May in the northwest, as soil reaches 55°F | Turf-type Tall Fescue |
| New York | Mid-April (Long Island/NYC) extending into early May (Buffalo/Upstate), as soil reaches 55°F | Kentucky Bluegrass |
| Pennsylvania | Mid-April around Philadelphia to early May on the northern plateau at soil 55°F — three weeks of spread across fifty miles where the ridges rise, which is why a neighbour's timing is not yours | Kentucky Bluegrass |
| Rhode Island | Crabgrass pre-emergent once soil holds 55°F at 2 inches — usually the second half of April on the bay and coastal towns, into early May inland | Kentucky Bluegrass |
| Washington | Mid-April to early May as soil reaches 55°F; crabgrass pressure is low west of the Cascades, where annual bluegrass and moss matter more | Perennial Ryegrass |
| Wisconsin | Late April to mid-May, as soil temperatures reach near 60°F for several consecutive days — forsythia bloom is the usual reminder | Kentucky Bluegrass |
| Maine | Crabgrass pre-emergent as soil holds 55°F at 2 inches — mid to late May on the southern coast, June inland; north of Bangor crabgrass pressure is often low enough that the honest answer is to skip it | Kentucky Bluegrass |
| Minnesota | Mid-May, as soil warms — the season opens later here than anywhere else we cover | Kentucky Bluegrass |
| Montana | Crabgrass pre-emergent as soil holds 55°F at 2 inches, which is generally May and can be late May at elevation — and crabgrass pressure in much of Montana is low enough that this is a decision rather than a default | Kentucky Bluegrass |
| North Dakota | Crabgrass pre-emergent as soil holds 55°F at 2 inches, usually mid to late May — and crabgrass pressure here is genuinely lower than in the states to the south, so this is a decision rather than a routine | Kentucky Bluegrass |
| South Dakota | Crabgrass pre-emergent as soil holds 55°F at 2 inches, generally mid-May — and pressure is lower here than in the corn-belt states, so it is a judgement rather than an annual purchase | Kentucky Bluegrass |
| Vermont | Crabgrass pre-emergent as soil holds 55°F at 2 inches — usually mid-May in the Champlain Valley and later in the hills; in the coldest towns crabgrass pressure is low enough that the question is whether to bother | Kentucky Bluegrass |
| Wyoming | Crabgrass pre-emergent as soil holds 55°F at 2 inches, generally May and later at elevation — pressure here is low enough that in much of the state this is a decision rather than an annual habit | Kentucky Bluegrass |
| Alaska | Largely beside the point: crabgrass and the summer annuals that drive pre-emergent programmes in the lower 48 are not the problem here, and a pre-emergent applied on a mainland schedule is money spent on an absent weed | Kentucky Bluegrass |
50 states published so far. Each window comes from that state's researched profile — the same data that powers itsstate huband localized guides. Not seeing yours? New states are prioritised by reader demand on the map page.
Where these windows come from
Each state's window is compiled from its land-grant university extension guidance — soil-temperature triggers, regional germination timing and, where extension programs use them, phenological signals like forsythia bloom. They arewindows, not dates: an early spring shifts everything forward, so treat the soil thermometer as the authority and the calendar as the reminder. Product labels remain the legal authority on rates and turf safety.
The guidance behind each state
- Arizona — A Turfgrass Maintenance Guide for Residential and Commercial Lawns in the Low Elevation Arizona Desert (University of Arizona Cooperative Extension)
- California — Crabgrass — Pest Notes (UC Statewide IPM Program)
- Florida — ENH884/EP141: Weed Management Guide for Florida Lawns (University of Florida IFAS Extension)
- Georgia — Weed Control in Home Lawns (University of Georgia Extension)
- Illinois — Maintaining Healthy Lawns (University of Illinois Extension)
- North Carolina — Carolina Lawns: A Guide to Maintaining Quality Turf in the Landscape (NC State Extension)
- Ohio — Time to think about Crabgrass control (Ohio State University Extension)
- Pennsylvania — Control of Summer Annual Grass Weeds in Turfgrasses (Penn State Extension)
- Tennessee — Crabgrass Species Control in Turfgrass (W146) (UT Institute of Agriculture Extension)
- Texas — Turfgrass Weeds (Texas A&M AgriLife Extension — Aggie Turf)
Where a state's extension program publishes a soil-temperature trigger we use it; where it publishes a calendar range instead, we print the range. We do not average the two, and we do not carry one state's window across a border.
Referencing this table in an article or newsletter is welcome — a link back to this page lets your readers find the year's revision.
Found your window? The next three steps
Pick the product
Prodiamine is the long-residual homeowner standard — one timed application covers the spring germination season.
Our Barricade review
Understand the sequence
Pre-emergent is step one of the spring plan; what's already sprouted needs a different product family.
Spring weed control guide
Know the enemy
The window above targets crabgrass — confirm that's actually what you're fighting before you buy.
Crabgrass guide
Common questions
Frequently Asked Questions
What soil temperature triggers pre-emergent application?
For crabgrass — the main spring target — the standard trigger is soil holding around 55°F at a 2-inch depth for several consecutive days, because that is when crabgrass seed germinates. Florida's window runs on a warmer 65°F trigger aimed at its subtropical weed mix. Soil temperature, not the calendar, is the real signal: the same date can be right one year and two weeks late the next.
How do I measure my soil temperature?
A soil thermometer pushed 2 inches into the lawn in mid-morning gives the number that matters — pick one with a short stem and 2°F subdivisions, because a long compost probe pushed shallowly reads closer to the air than the soil. If you would rather not measure, most state extension services publish live soil temperature maps, and a classic proxy in northern states is forsythia bloom — Ohio extension programs have used it as the application signal for decades.
What if I missed my state's pre-emergent window?
Skip it rather than applying late — pre-emergent has no effect on weeds that have already germinated, so a late application wastes the product and still blocks any overseeding for months. Switch to a post-emergent plan for the weeds that come up this season, and put the pre-emergent date on next year's calendar.
Do I need a second application in fall?
In much of the country, yes — winter annuals like henbit, chickweed and annual bluegrass germinate in early fall, and a September application stops the weeds you would otherwise fight the following spring. In Arizona the fall pass matters for a different reason: winter weeds germinate inside overseeded ryegrass. Check your state's row and hub page for the local pattern.