Frost dates for Hillsboro, OR
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
April 16
typical year
Safe to plant
May 3
frost is over in 9 of 10 years
First fall frost
October 23
typical year
Growing season
191 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | Mar 19 – Apr 2 | – |
| Spinach | – | Mar 5 – 26 | Aug 28 – Sep 11 |
| Lettuce | – | Mar 19 – Apr 9 | Aug 28 – Sep 11 |
| Radishes | – | Mar 19 – Apr 30 | Sep 11 – 25 |
| Onions | – | Mar 19 – Apr 2 | – |
| Potatoes | – | Mar 26 – Apr 9 | – |
| Carrots | – | Mar 26 – Apr 16 | Jul 31 – Aug 14 |
| Beets | – | Mar 19 – Apr 2 | Aug 14 – 28 |
| Kale | Feb 5 – 19 | Mar 19 – Apr 2 | Aug 14 – 28 |
| Broccoli | Feb 5 – 19 | Apr 2 – 16 | Aug 14 – 28 |
| Cabbage | Jan 22 – Feb 5 | Mar 19 – Apr 2 | Aug 14 – 28 |
| Garlic | – | – | Sep 11 – Oct 2 |
| Warm-season crops | |||
| Tomatoes | Mar 8 – 22 | May 3 – 17 | – |
| Peppers | Mar 1 – 15 | May 10 – 24 | – |
| Cucumbers | – | May 3 – 24 | – |
| Zucchini | – | May 3 – 31 | – |
| Pumpkins | – | May 3 – 24 | – |
| Green beans | – | May 3 – Aug 14 | – |
| Sweet corn | – | May 3 – 31 | – |
| Basil | Mar 29 – Apr 12 | May 10 – 17 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | May 3 | April 16 | March 25 |
| Fall frost before | October 3 | October 23 | November 18 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around March 13 (April 9 in a late year), and the first one in fall around November 12.
Towns that use these dates
This is the nearest NOAA station with frost records for 2 towns.
Hillsboro, North Plains
Where these dates come from
NOAA weather station PORTLAND-HILLSBORO AP, OR US (USW00094261), 1991–2020 climate normals. It's the nearest station for 2 zip codes, all within 7 miles:
97123, 97124
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.