USDA Hardiness Zone 9a
Frost Dates for 97380 — Siletz, Oregon
Averages from Newport 3n, Or US, the nearest reporting station, 8.1 miles away.
Plant tender crops after March 12, and expect the first autumn freeze around December 10. That leaves about 271 frost-free days.
- Last spring frost
- March 12
- First fall frost
- December 10
- Growing season
- 271 days
- Hardiness zone
- 9a
50% probability
50% probability
frost-free
20 to 25°F annual low
Planting calendar for 97380
| When | What to do |
|---|---|
| January 1 – January 15 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| January 15 – January 29 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| February 12 – February 26 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| March 12 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by September 17 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by November 26 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| December 10 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 March 12 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Siletz, Oregon are past their last freeze. Harvest before December 10, which leaves roughly 271 frost-free days.
ZIP 97380 sits in USDA hardiness zone 9a, meaning the average coldest night of the year falls between 20 to 25°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.