The average dates are established at the 50% level or half the times the frost may occur before or after that date. The safe date is when there is less than a 10% chance the frost will be after (for last frost) or that it will occur before (the first frost). You certainly will have your own little micro-climates around your landscape to modify your planting times. You can always use season extenders to modify these areas. These techniques are not limited to greenhouses or row covers.
| Location | Average Last Frost (Date) | Safe Last Frost (Date) | Average First Frost (Date) | Safe First Frost (Date) | Average Growing Season (Days) | Safe Growing Season (Days) |
|---|---|---|---|---|---|---|
| Baker Airport | 6/3 | 6/29 | 9/7 | 8/26 | 95 | 64 |
| Baker Area | 5/30 | 6/20 | 9/22 | 9/8 | 115 | 89 |
| Halfway | 6/11 | 7/3 | 9/10 | 8/28 | 90 | 64 |
| Huntington | 4/30 | 5/17 | 10/9 | 9/22 | 161 | 137 |
| La Grande | 5/17 | 6/11 | 9/26 | 9/9 | 130 | 98 |
| Ontario | 5/12 | 6/3 | 9/28 | 9/14 | 139 | 108 |
| Richland | 5/22 | 6/12 | 9/26 | 10/8 | 126 | 94 |
| Union | 5/24 | 6/12 | 9/17 | 9/2 | 116 | 94 |
| Vale | 5/13 | 6/2 | 9/30 | 9/16 | 139 | 114 |
Want to learn more about this topic? Explore more resources from OSU Extension:
Gardening techniques
