Colorado frost dates: I
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Idaho Springs | May 30 | Sep 19 | 112 d | 5b |
| Idalia | May 4 | Oct 9 | 158 d | 6a |
| Idledale | May 23 | Sep 22 | 122 d | 5b |
| Ignacio | May 23 | Sep 29 | 129 d | 6a |
| Iliff | Apr 30 | Oct 9 | 162 d | 5b |
| Indian Hills | May 23 | Sep 22 | 122 d | 5b |