Growing Season Length by State (Frost-Free Days)
The growing season - the period between last spring frost and first fall frost - determines what you can grow and when. Here are the frost-free days for every US state.
Growing Season by State
The following table shows average frost-free growing season length, last spring frost, and first fall frost dates for each state's most populated agricultural areas:
| State | Last Spring Frost | First Fall Frost | Frost-Free Days |
|---|---|---|---|
| Alabama | March 19 | November 1 | 227 |
| Arizona | March 1 (Phoenix) | December 15 | 288 |
| Arkansas | March 28 | November 5 | 222 |
| California | Feb 1 (coastal) / April 30 (mountain) | Variable | 180-365 |
| Colorado | May 11 | October 1 | 143 |
| Connecticut | April 20 | October 10 | 173 |
| Florida | January 15 (N. FL) / None (S. FL) | December 15 | 300-365 |
| Georgia | March 24 | November 10 | 231 |
| Idaho | May 11 | October 1 | 143 |
| Illinois | April 22 | October 14 | 175 |
| Iowa | April 30 | October 7 | 160 |
| Kansas | April 19 | October 17 | 181 |
| Kentucky | April 14 | October 22 | 191 |
| Louisiana | February 28 | December 1 | 276 |
| Maine | May 15 | September 25 | 133 |
| Massachusetts | April 20 | October 15 | 178 |
| Michigan | May 5 | October 8 | 156 |
| Minnesota | May 11 | September 29 | 141 |
| Mississippi | March 15 | November 7 | 237 |
| Missouri | April 14 | October 21 | 190 |
| Montana | May 21 | September 17 | 119 |
| Nebraska | April 30 | October 9 | 162 |
| Nevada | April 14 (Las Vegas) / June 1 (Reno) | October 29 / September 22 | 199 / 114 |
| New York | April 27 | October 10 | 166 |
| North Carolina | March 30 | November 5 | 220 |
| North Dakota | May 21 | September 21 | 123 |
| Ohio | April 23 | October 20 | 180 |
| Oklahoma | March 28 | November 7 | 224 |
| Oregon | March 25 (Portland) / May 25 (eastern) | November 15 / October 1 | 235 / 129 |
| Pennsylvania | April 23 | October 14 | 174 |
| Tennessee | March 31 | November 1 | 215 |
| Texas | Feb 15 (Houston) / April 1 (N. Texas) | December 10 / November 10 | 298 / 224 |
| Utah | April 29 | October 14 | 168 |
| Virginia | April 9 | October 26 | 200 |
| Washington | March 21 (Seattle) / May 15 (eastern) | November 11 / October 5 | 235 / 143 |
| Wisconsin | May 5 | October 7 | 155 |
| Wyoming | May 22 | September 22 | 123 |
Extending the Growing Season
Gardeners use several techniques to extend the growing season beyond average frost dates:
- Cold frames and row covers - Extend 4-6 weeks in both spring and fall
- Greenhouses - Year-round growing possible in any climate
- Raised beds - Soil warms faster in spring, extending planting season 2-3 weeks
- Microclimate selection - South-facing slopes and walls with thermal mass can be 5-10°F warmer than surrounding areas
Climate Change Effects
Over the past 50 years, growing seasons in the US have lengthened by an average of 10-14 days, primarily due to earlier last spring frosts rather than later fall frosts. This trend is most pronounced in the western US and least pronounced in the Southeast.