Frost dates · USDA zone 8b
Frost dates for Hillsboro, OR
Hillsboro, OR sees its last 32 °F night of spring around April 16 and its first of fall around October 23 — a 191-day freeze-free season in a typical year.
Pick a sauce; the Plan Builder runs this station's dates and hands back the calendar, plant count and gear list.
Freeze odds, by date
| Odds | Last spring freeze after | First fall freeze before |
|---|---|---|
| 9 years in 10 | Mar 25 | Nov 18 |
| Median — 1 year in 2 | Apr 16 | Oct 23 |
| 1 year in 10 | May 3 | Oct 3 |
The top row is the risky edge: in 9 years of 10 a spring freeze still comes after it, so tender transplants set out then need cover. The bottom row is the cautious date — only 1 year in 10 freezes after it — and the one to plan uncovered tender transplants against. Freeze-free season: 191 days median, at least 161 in 9 years of 10, at least 223 days in 1 year of 10. NOAA ranks season length year by year, so it is not the gap between two rows above. A hard freeze (28 °F) has a median last date of Mar 13 and first of Nov 12.
Hillsboro planting calendar, 2027
Every row runs from the median last frost (Apr 16) and median first frost (Oct 23) above, using each cultivar's days to maturity. Same engine as the Plan Builder.
| Crop | Start indoors | Transplant / plant | First harvest | Days |
|---|---|---|---|---|
| Hardneck GarlicSiberian (porcelain hardneck) | — | Oct 15prior fall | Jun 12 | 240 from sow |
| Spanish OnionYellow Sweet Spanish (long-day) | Jan 22 | Mar 19 | Jul 7 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Apr 16 | May 16 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Apr 2 | Apr 2 | May 17 | 45 from sow |
| Genovese BasilGenovese | Mar 19 | Apr 30 | Jun 29 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Feb 19 | Apr 23 | Jul 7 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Feb 5 | Apr 30 | Aug 3 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Feb 19 | Apr 23 | Jul 7 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Feb 19 | Apr 23 | Jul 12 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Feb 19 | Apr 23 | Jul 12 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Apr 2 | Apr 2 | Jun 11 | 70 from sow |
| TomatilloToma Verde | Mar 5 | Apr 23 | Jul 2 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Mar 5 | Apr 23 | Jul 7 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Mar 5 | Apr 23 | Jul 12 | 80 from transplant |
Tight means first harvest lands within two weeks of the median first fall frost: start that crop indoors on time or cover it in fall.
What sauce can Hillsboro grow?
Each sauce, scheduled for a Hillsboro container garden: when the first seeds go in and when enough fruit has ripened for one batch.
Hillsboro frost questions
When is the last frost in Hillsboro, OR?
The median last 32 °F freeze at PORTLAND-HILLSBORO AP, OR is April 16: half of years see a later one. One year in ten, a freeze still comes after May 3; nine years in ten, it comes after March 25. Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in Hillsboro, OR?
The median first 32 °F freeze of fall is October 23. One year in ten it arrives before October 3; nine years in ten, before November 18.
How long is the growing season in Hillsboro, OR?
191 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 161 days; one year in ten, at least 223 days.
What growing zone is Hillsboro, OR?
USDA hardiness zone 8b, per the 2023 USDA Plant Hardiness Zone Map for ZIP 97124. A zone describes the coldest winter night, not when frost ends, so it is the wrong number for a planting calendar — the frost dates on this page are the right one.
When should I plant tomatoes in Hillsboro, OR?
Start Roma VF (determinate paste) seeds indoors around Mar 5 and transplant around Apr 23, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for May 3. First ripe fruit lands around Jul 7.
When should I plant peppers in Hillsboro, OR?
Sow jalapeño indoors on a heat mat around Feb 19; transplant no earlier than Apr 23, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Jul 7.
Nearby in Oregon
- Beavertonlast frost Feb 11
- Tigardlast frost Apr 1
- Portlandlast frost Feb 25
- Greshamlast frost Mar 16
- Salemlast frost Apr 3
- Albanylast frost Apr 17
All Oregon frost dates → · How frost-date math drives a sowing calendar →