Tennessee frost dates: O
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Oak Ridge | Mar 31 | Nov 4 | 218 d | 7b |
| Oakdale | Apr 3 | Nov 4 | 215 d | 7b |
| Oakfield | Apr 4 | Oct 30 | 209 d | 7b |
| Oakland | Mar 29 | Nov 3 | 219 d | 8a |
| Obion | Apr 3 | Nov 1 | 212 d | 7b |
| Ocoee | Apr 6 | Oct 30 | 207 d | 7b |
| Old Fort | Apr 7 | Oct 29 | 205 d | 7b |
| Old Hickory | Apr 1 | Nov 4 | 217 d | 7b |
| Olivehill | Apr 14 | Oct 24 | 193 d | 7b |
| Oliver Springs | Apr 5 | Nov 1 | 210 d | 7b |
| Oneida | Apr 23 | Oct 18 | 178 d | 7a |
| Only | Apr 13 | Oct 24 | 194 d | 7b |
| Ooltewah | Mar 24 | Nov 9 | 230 d | 8a |
| Orlinda | Apr 5 | Nov 1 | 210 d | 7a |