Data Story
Growing Season Length by State — NOAA Climate Data
Source: NOAA National Centers for Environmental Information, 30-Year Climate Normals 1991-2020.
Analyzed by Growable Ground, April 2026.
Last updated:
Frost-Free Window
60 - 365 days
NOAA 30-year normals
GDD Accumulation
Varies by zone
Estimated from USDA hardiness zone
Season Types
3 classifications
Short / Medium / Long
Example: Massachusetts Frost Timeline
The green bar shows the frost-free growing window. Amber zones indicate frost risk periods.
What Frost-Free Days Mean for Your Garden
The frost-free growing season — the span between your last spring frost and first fall frost — determines which crops you can grow outdoors. Different crops have different minimum requirements:
If your frost-free season is shorter than a crop's requirement, you can extend it with season-extension techniques: row covers, cold frames, greenhouses, or starting seeds indoors and transplanting after the last frost.
All 50 States — Frost Dates and Growing Season Length
Sorted by longest growing season. Frost-free days are estimated ranges reflecting geographic variation within each state.
| State | Zones | Last Frost | First Frost | Frost-Free Days |
|---|---|---|---|---|
| Hawaii | 8b-13a | None on record | None on record | 365 |
| Florida | 8b-12a | Jan 25 - Feb 10 | Dec 7 - Dec 18 | 320 |
| California | 4b-11a | Jan 19 - Mar 19 | Nov 29 - Dec 12 | 317 |
| Louisiana | 8b-10b | Jan 30 - Feb 17 | Nov 30 - Dec 8 | 298 |
| Georgia | 7a-9b | Feb 17 - Mar 10 | Nov 24 - Dec 4 | 275 |
| Texas | 6b-10b | Feb 10 - Mar 12 | Nov 18 - Dec 4 | 274 |
| Mississippi | 7b-9b | Feb 17 - Mar 3 | Nov 21 - Nov 30 | 273 |
| Alabama | 7b-9b | Feb 24 - Mar 16 | Nov 15 - Nov 28 | 266 |
| Arizona | 5b-10b | Feb 1 - Apr 2 | Nov 13 - Dec 12 | 266 |
| South Carolina | 7a-9b | Feb 27 - Mar 12 | Nov 23 - Dec 1 | 265 |
| Arkansas | 6b-8b | Mar 2 - Mar 20 | Nov 15 - Nov 23 | 254 |
| District of Columbia | 7b-8a | Mar 15 | Nov 24 | 254 |
| North Carolina | 6a-9a | Mar 11 - Mar 24 | Nov 10 - Nov 25 | 245 |
| Delaware | 7a-8a | Mar 23 - Mar 23 | Nov 17 - Nov 19 | 241 |
| Maryland | 5b-8a | Mar 18 - Mar 29 | Nov 11 - Nov 27 | 238 |
| Oklahoma | 6b-8b | Mar 15 - Mar 26 | Nov 9 - Nov 14 | 237 |
| Tennessee | 6a-8a | Mar 21 - Mar 29 | Nov 5 - Nov 12 | 230 |
| Rhode Island | 6b-7b | Mar 27 - Apr 3 | Nov 7 - Nov 21 | 225 |
| Virginia | 5b-8b | Mar 22 - Apr 2 | Nov 2 - Nov 17 | 224 |
| New Jersey | 6a-8a | Mar 26 - Apr 4 | Nov 5 - Nov 17 | 222 |
| Kentucky | 6a-7b | Mar 27 - Apr 2 | Nov 4 - Nov 10 | 221 |
| Missouri | 5b-8a | Mar 27 - Apr 2 | Oct 31 - Nov 7 | 219 |
| Oregon | 5a-10a | Feb 25 - Apr 26 | Oct 19 - Nov 26 | 213 |
| Illinois | 5a-7b | Mar 29 - Apr 8 | Oct 28 - Nov 5 | 212 |
| Indiana | 5b-7b | Apr 4 - Apr 9 | Oct 30 - Nov 4 | 209 |
| New Mexico | 5a-9a | Mar 31 - Apr 19 | Oct 22 - Nov 9 | 209 |
| Ohio | 5b-7a | Apr 5 - Apr 13 | Oct 31 - Nov 6 | 208 |
| Washington | 4a-9b | Mar 16 - Apr 15 | Oct 24 - Nov 18 | 208 |
| Kansas | 5b-7a | Apr 1 - Apr 12 | Oct 25 - Nov 3 | 208 |
| Connecticut | 6a-7b | Mar 31 - Apr 11 | Oct 30 - Nov 3 | 207 |
| Massachusetts | 5a-7b | Apr 4 - Apr 14 | Oct 24 - Nov 14 | 206 |
| West Virginia | 5b-7a | Apr 4 - Apr 15 | Oct 26 - Nov 5 | 204 |
| Pennsylvania | 5b-8a | Apr 6 - Apr 24 | Oct 25 - Nov 3 | 197 |
| Iowa | 4b-6a | Apr 10 - Apr 17 | Oct 18 - Oct 23 | 189 |
| Michigan | 4a-7a | Apr 19 - May 8 | Oct 12 - Oct 31 | 186 |
| New York | 4a-7b | Apr 13 - Apr 29 | Oct 18 - Nov 5 | 185 |
| Maine | 3b-7a | Apr 16 - May 3 | Oct 10 - Oct 24 | 182 |
| Nebraska | 4b-6a | Apr 12 - Apr 26 | Oct 15 - Oct 21 | 181 |
| Utah | 4a-9a | Apr 12 - May 6 | Oct 8 - Oct 27 | 175 |
| Minnesota | 3a-5a | Apr 19 - Apr 30 | Oct 10 - Oct 17 | 174 |
| Wisconsin | 3b-6a | Apr 17 - May 2 | Oct 9 - Oct 21 | 173 |
| New Hampshire | 3b-6b | Apr 22 - May 4 | Oct 10 - Oct 21 | 171 |
| South Dakota | 4a-5b | Apr 22 - Apr 29 | Oct 9 - Oct 15 | 168 |
| Nevada | 4a-10a | Apr 28 - May 20 | Oct 9 - Oct 21 | 163 |
| Vermont | 4a-6a | Apr 27 - May 5 | Oct 10 - Oct 17 | 163 |
| Idaho | 3b-8a | Apr 26 - May 17 | Oct 1 - Oct 17 | 160 |
| North Dakota | 3b-4b | Apr 30 - May 6 | Oct 4 - Oct 9 | 157 |
| Colorado | 3b-7b | Apr 25 - May 19 | Sep 29 - Oct 16 | 155 |
| Montana | 3a-6b | May 2 - May 13 | Sep 28 - Oct 7 | 151 |
| Wyoming | 3b-6a | May 4 - May 13 | Sep 30 - Oct 7 | 151 |
| Alaska | 1a-9a | Apr 16 - May 15 | Sep 24 - Oct 29 | 147 |
Frost dates represent statewide ranges. Individual parcels may differ significantly based on elevation, slope, and proximity to water.
Why State Averages Aren't Enough
Colorado's growing season ranges from under 60 days in the high Rockies to over 180 days on the eastern plains. California spans from mountain parcels with fewer than 150 frost-free days to coastal areas with 365. A single state number doesn't tell you what you can grow on your specific land.
Local factors that shift frost dates by 2-4 weeks compared to the nearest weather station: elevation (2 degrees F cooler per 1,000 ft), cold-air pooling in valleys, proximity to large water bodies, south- vs north-facing slopes, and urban heat island effects.
See YOUR exact frost dates — NOAA data for your specific parcel
Your Growable Ground report calculates frost dates from the nearest NOAA station to your parcel, not state averages.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Read our complete guide to frost dates and season planning
Frequently Asked Questions
What determines growing season length?
NOAA defines the growing season as the number of frost-free days between the average last spring frost (32 degrees F) and the average first fall frost (32 degrees F), calculated from 30-year climate normals (1991-2020).
How many frost-free days do common crops need?
Lettuce and radishes need as few as 30-45 frost-free days. Tomatoes need 60-85 days. Peppers need 60-90 days. Sweet potatoes need 90-120 days. Watermelons need 80-100 days. Citrus trees need year-round frost protection.
Can my growing season differ from the state average?
Yes, significantly. Elevation, slope, proximity to water bodies, and urban heat island effects can shift frost dates by 2-4 weeks compared to state averages. Valley bottoms experience frost earlier in fall and later in spring than hilltops just one mile away.