Frost Dates for Wilsonville, OR
In Wilsonville, OR, the average last spring frost is around Mar 18 and the average first fall frost around Nov 13, for a growing season of about 243 days. For frost-tender plants, wait until Apr 10, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the N Willamette Exp Stn, OR weather station, 2 miles away, elevation 150 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | Apr 10 | Oct 27 |
| 20% | Apr 2 | Nov 1 |
| 30% | Mar 28 | Nov 5 |
| 40% | Mar 23 | Nov 10 |
| 50% | Mar 18 | Nov 13 |
| 60% | Mar 13 | Nov 18 |
| 70% | Mar 8 | Nov 23 |
| 80% | Mar 1 | Nov 30 |
| 90% | Feb 22 | Dec 6 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | Apr 17 | Oct 27 |
| Frost / freeze (32°F) | Mar 18 | Nov 13 |
| Hard freeze (28°F) | Feb 13 | Dec 1 |
Planting calendar for Wilsonville
Transplant Mar 25 – Apr 8
Transplant Apr 1 – Apr 15
Transplant Apr 1 – Apr 15
Transplant Mar 25 – Apr 8
Sow or transplant Mar 25 – Apr 8
Sow or transplant Mar 25 – Apr 8
Sow or transplant Apr 1 – Apr 15
Sow or transplant Feb 18 – Mar 4
Fall sowing Sep 18 – Oct 16
Fall sowing Sep 18 – Oct 9
Fall sowing Sep 4 – Sep 18
Sow or transplant Feb 18 – Mar 4
Fall sowing Sep 4 – Oct 2
Transplant Mar 4 – Mar 18
Fall sowing Aug 21 – Sep 4
Transplant Feb 25 – Mar 11
Fall sowing Aug 21 – Sep 4
Fall sowing Aug 21 – Sep 4
Fall sowing Oct 2 – Oct 23
Fall sowing Sep 4 – Sep 18
Plant Feb 18 – Mar 4
Based on the average last frost (Mar 18) and first frost (Nov 13). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.