USDA Hardiness Zone 8b
Frost Dates for 97113 — Cornelius, Oregon
Averages from Forest Grove, Or US, the nearest reporting station, 2.6 miles away.
Plant tender crops after April 16, and expect the first autumn freeze around October 26. That leaves about 192 frost-free days.
- Last spring frost
- April 16
- First fall frost
- October 26
- Growing season
- 192 days
- Hardiness zone
- 8b
50% probability
50% probability
frost-free
15 to 20°F annual low
Planting calendar for 97113
| When | What to do |
|---|---|
| February 5 – February 19 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| February 19 – March 5 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| March 19 – April 2 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| April 16 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by August 3 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by October 12 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| October 26 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after April 16 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Cornelius, Oregon are past their last freeze. Harvest before October 26, which leaves roughly 192 frost-free days.
ZIP 97113 sits in USDA hardiness zone 8b, meaning the average coldest night of the year falls between 15 to 20°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.