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.
Frost-Free Window
60 - 365 days
NOAA 30-year normals
GDD Accumulation
Varies by zone
PRISM Climate Data
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 |
|---|---|---|---|---|
| California | 5a-11a | Jan 15 - May 15 | Oct 1 - Dec 31 | 139-350 |
| Arizona | 4b-10b | Jan 15 - May 1 | Oct 15 - Dec 15 | 167-334 |
| Texas | 6b-10a | Feb 1 - Apr 15 | Oct 15 - Dec 15 | 183-317 |
| Louisiana | 8a-9b | Feb 15 - Mar 15 | Nov 10 - Dec 10 | 240-298 |
| Georgia | 6b-9a | Mar 1 - Apr 15 | Oct 15 - Nov 30 | 183-274 |
| Alabama | 7a-9a | Feb 28 - Apr 5 | Oct 25 - Nov 20 | 203-265 |
| Mississippi | 7b-9a | Feb 28 - Mar 30 | Oct 25 - Nov 20 | 209-265 |
| South Carolina | 7a-9a | Mar 1 - Apr 10 | Oct 20 - Nov 20 | 193-264 |
| Oregon | 4b-9b | Mar 1 - Jun 15 | Sep 1 - Nov 15 | 78-259 |
| Washington | 4a-9a | Mar 1 - Jun 1 | Sep 15 - Nov 15 | 106-259 |
| North Carolina | 5b-8b | Mar 10 - May 5 | Oct 5 - Nov 15 | 153-250 |
| Nevada | 4a-9b | Mar 15 - Jun 1 | Sep 15 - Nov 15 | 106-245 |
| Arkansas | 6b-8a | Mar 15 - Apr 15 | Oct 15 - Nov 10 | 183-240 |
| New Mexico | 4b-8b | Mar 15 - May 30 | Sep 15 - Nov 10 | 108-240 |
| Virginia | 5b-8a | Mar 20 - May 10 | Oct 1 - Nov 10 | 144-235 |
| Oklahoma | 6b-8a | Mar 20 - Apr 15 | Oct 15 - Nov 5 | 183-230 |
| Tennessee | 6a-7b | Mar 20 - Apr 20 | Oct 10 - Nov 5 | 173-230 |
| District of Columbia | 7b-8a | Apr 1 - Apr 20 | Oct 25 - Nov 15 | 188-228 |
| Maryland | 5b-8a | Mar 25 - May 5 | Oct 5 - Nov 5 | 153-225 |
| Delaware | 7a-7b | Apr 1 - Apr 20 | Oct 15 - Nov 5 | 178-218 |
| New Jersey | 6a-7b | Apr 1 - May 1 | Oct 5 - Nov 5 | 157-218 |
| New York | 3b-7b | Apr 1 - May 30 | Sep 15 - Nov 1 | 108-214 |
| Illinois | 5a-7a | Apr 5 - May 10 | Sep 30 - Oct 30 | 143-208 |
| Kansas | 5b-7a | Apr 5 - May 1 | Oct 5 - Oct 30 | 157-208 |
| Kentucky | 6a-7a | Apr 5 - Apr 25 | Oct 10 - Oct 30 | 168-208 |
| Missouri | 5b-7a | Apr 5 - Apr 25 | Oct 5 - Oct 30 | 163-208 |
| Massachusetts | 5a-7b | Apr 10 - May 20 | Sep 20 - Oct 30 | 123-203 |
| Ohio | 5b-6b | Apr 15 - May 15 | Sep 30 - Oct 30 | 138-198 |
| Indiana | 5b-6b | Apr 10 - May 10 | Oct 1 - Oct 25 | 144-198 |
| Pennsylvania | 5a-7a | Apr 10 - May 15 | Sep 25 - Oct 25 | 133-198 |
| Rhode Island | 6a-7a | Apr 10 - May 1 | Oct 5 - Oct 25 | 157-198 |
| Utah | 4a-8a | Apr 10 - Jun 1 | Sep 15 - Oct 25 | 106-198 |
| Connecticut | 5b-7a | Apr 15 - May 15 | Sep 25 - Oct 25 | 133-193 |
| West Virginia | 5a-6b | Apr 15 - May 15 | Sep 25 - Oct 20 | 133-188 |
| Colorado | 3a-7a | Apr 15 - Jun 15 | Aug 25 - Oct 15 | 71-183 |
| Idaho | 3b-7a | Apr 15 - Jun 15 | Sep 1 - Oct 15 | 78-183 |
| Michigan | 4a-6b | Apr 20 - May 30 | Sep 15 - Oct 20 | 108-183 |
| Nebraska | 4a-5b | Apr 15 - May 10 | Sep 25 - Oct 15 | 138-183 |
| Iowa | 4b-5b | Apr 20 - May 15 | Sep 25 - Oct 15 | 133-178 |
| Wisconsin | 3b-5b | Apr 25 - May 25 | Sep 15 - Oct 15 | 113-173 |
| Minnesota | 3a-4b | Apr 25 - May 30 | Sep 10 - Oct 10 | 103-168 |
| Maine | 3b-6a | May 1 - Jun 5 | Sep 10 - Oct 10 | 97-162 |
| New Hampshire | 3b-6a | May 1 - Jun 1 | Sep 10 - Oct 10 | 101-162 |
| South Dakota | 3b-5a | May 1 - May 30 | Sep 10 - Oct 5 | 103-157 |
| Alaska | 1a-7b | May 1 - Jun 15 | Aug 15 - Oct 1 | 61-153 |
| Montana | 3a-5b | May 1 - Jun 15 | Aug 25 - Oct 1 | 71-153 |
| Vermont | 3b-5b | May 5 - Jun 1 | Sep 10 - Oct 5 | 101-153 |
| North Dakota | 3a-4b | May 5 - Jun 1 | Sep 10 - Oct 1 | 101-149 |
| Wyoming | 3a-5b | May 10 - Jun 15 | Aug 25 - Sep 25 | 71-138 |
| Florida | 8a-11b | Jan 1 - Mar 15 | Nov 15 - never (south FL) | 245-0 |
| Hawaii | 10a-13a | None | None | 0-0 |
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.