Frost dates for Ontario, 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 22
typical year
Safe to plant
May 7
frost is over in 9 of 10 years
First fall frost
October 9
typical year
Growing season
168 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 25 – Apr 8 | – |
| Spinach | – | Mar 11 – Apr 1 | Aug 14 – 28 |
| Lettuce | – | Mar 25 – Apr 15 | Aug 14 – 28 |
| Radishes | – | Mar 25 – May 6 | Aug 28 – Sep 11 |
| Onions | – | Mar 25 – Apr 8 | – |
| Potatoes | – | Apr 1 – 15 | – |
| Carrots | – | Apr 1 – 22 | Jul 17 – 31 |
| Beets | – | Mar 25 – Apr 8 | Jul 31 – Aug 14 |
| Kale | Feb 11 – 25 | Mar 25 – Apr 8 | Jul 31 – Aug 14 |
| Broccoli | Feb 11 – 25 | Apr 8 – 22 | Jul 31 – Aug 14 |
| Cabbage | Jan 28 – Feb 11 | Mar 25 – Apr 8 | Jul 31 – Aug 14 |
| Garlic | – | – | Aug 28 – Sep 18 |
| Warm-season crops | |||
| Tomatoes | Mar 12 – 26 | May 7 – 21 | – |
| Peppers | Mar 5 – 19 | May 14 – 28 | – |
| Cucumbers | – | May 7 – 28 | – |
| Zucchini | – | May 7 – Jun 4 | – |
| Pumpkins | – | May 7 – 28 | – |
| Green beans | – | May 7 – Jul 31 | – |
| Sweet corn | – | May 7 – Jun 4 | – |
| Basil | Apr 2 – 16 | May 14 – 21 | – |
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 7 | April 22 | April 7 |
| Fall frost before | September 26 | October 9 | October 23 |
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 April 6 (April 23 in a late year), and the first one in fall around October 21.
Towns that use these dates
This is the nearest NOAA station with frost records for 3 towns.
Ontario, Fruitland, ID, New Plymouth, ID
Where these dates come from
NOAA weather station ONTARIO KSRV, OR US (USC00356294), 1991–2020 climate normals. It's the nearest station for 1 zip code, all within 11 miles:
83655
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.