When to plant in Cornelius, OR
USDA Zone 8bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Cornelius, Oregon — all computed from Cornelius's nearest NOAA weather station.
Zone 8b means many perennials and even some tender shrubs overwinter in Cornelius, while your frost dates still decide when annuals go out.
Frost probability
FOREST GROVE · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Cornelius’s own odds, recorded at FOREST GROVE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 25 | May 4 | Apr 19 | Sep 24 | Oct 8 | Oct 30 |
| 32°F | May 5 | Apr 16 | Mar 26 | Oct 6 | Oct 26 | Nov 14 |
| 28°F | Apr 12 | Mar 19 | Feb 21 | Oct 23 | Nov 11 | Dec 5 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Cornelius, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 17 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Cornelius planting FAQ
When is the last spring frost in Cornelius, OR?
Plan for the last spring frost in Cornelius around April 16 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Cornelius, OR?
Expect Cornelius's first fall frost near October 26 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Cornelius in?
Cornelius is in USDA hardiness zone 8b. In zone 8b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Cornelius?
There are roughly 193 frost-free days in Cornelius (a moderate growing season), running from the average last frost around April 16 to the first fall frost near October 26.
When should I plant tomatoes in Cornelius?
In Cornelius, start tomato seeds indoors around February 19–March 5, then transplant seedlings outdoors around April 23 once the danger of frost has passed.
Never miss a window in Cornelius
An email when it’s time to start seeds, transplant, and sow — timed to Cornelius’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Forest Grove · 5 km
- Hillsboro · 9 km
- Aloha · 14 km
- Oak Hills · 17 km
- Bethany · 17 km
- Beaverton · 19 km
- Cedar Mill · 20 km
- Tigard · 23 km
Frost dates recorded at FOREST GROVE, 4 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Cornelius, OR — Frost Dates & Zone 8b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00352997. Retrieved from https://blissgarden.com/oregon/cornelius.