Boise, ID planting zone & frost dates
Boise is in USDA hardiness zone 7a. The last spring frost usually comes around April 24 and the first fall frost around October 21, for a growing season of about 179 days.
Planting calendar for Boise
Dates are counted from the average last spring frost (April 24) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: May 1 – May 8 |
| Peppers | Start seeds indoors: Feb 13 – Feb 27 Transplant outdoors: May 8 – May 15 |
| Eggplant | Start seeds indoors: Feb 13 – Feb 27 Transplant outdoors: May 8 – May 15 |
| Broccoli | Start seeds indoors: Feb 13 – Feb 27 Transplant outdoors: Mar 27 – Apr 10 |
| Cabbage | Start seeds indoors: Feb 13 – Feb 27 Transplant outdoors: Mar 27 – Apr 10 |
| Onions (sets) | Plant outdoors: Mar 27 – Apr 10 |
| Peas | Sow outdoors: Mar 13 – Mar 27 |
| Spinach | Sow outdoors: Mar 13 – Mar 27 |
| Lettuce | Sow outdoors: Mar 27 – Apr 10 |
| Carrots | Sow outdoors: Mar 27 – Apr 10 |
| Potatoes | Plant outdoors: Mar 27 – Apr 10 |
| Beans | Sow outdoors: May 1 – May 8 |
| Sweet corn | Sow outdoors: May 1 – May 8 |
| Cucumbers | Sow outdoors: May 1 – May 8 |
| Squash & zucchini | Sow outdoors: May 1 – May 8 |
| Basil | Start seeds indoors: Mar 13 – Mar 27 Transplant outdoors: May 1 – May 8 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 26 (8 weeks before the average first fall frost on Oct 21).
Useful for zone 7a gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 4 | Apr 24 | May 9 |
| First 32°F frost in fall is before | Nov 5 | Oct 21 | Oct 5 |
How to read it: in spring there is a 10% chance of a frost after May 9, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 5. A hard freeze (28°F) usually ends around April 2.
Hardiness zone by ZIP code in Boise
- 83701 zone 7a
- 83702 zone 7a
- 83703 zone 7a
- 83704 zone 7a
- 83705 zone 7a
- 83706 zone 7a
- 83707 zone 7a
- 83708 zone 7a
- 83709 zone 7a
- 83711 zone 7a
- 83712 zone 7a
- 83713 zone 7a
- 83715 zone 7a
- 83716 zone 6b
- 83717 zone 7a
- 83719 zone 7a
- 83720 zone 7a
- 83722 zone 7a
- 83724 zone 7a
- 83726 zone 7a
- 83728 zone 7a
- 83729 zone 7a
- 83732 zone 7a
- 83735 zone 7a
- 83756 zone 7a
- 83799 zone 7a
Nearby cities
- Garden City zone 7a, last frost Apr 24
- Eagle zone 7a, last frost Apr 24
- Meridian zone 7a, last frost Apr 24
- Eagle Foothills zone 7a, last frost Apr 30
- Kuna zone 7a, last frost Apr 24
- Nampa zone 7a, last frost Apr 29
- Caldwell zone 7a, last frost Apr 23
- Jerome zone 6b, last frost May 2
Questions
What growing zone is Boise, ID?
Boise is in USDA Plant Hardiness Zone 7a (average extreme winter low 0°F to 5°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 6b.
When is the last frost in Boise?
The average last spring frost (32°F) in Boise is April 24. There is still a 10% chance of frost until May 9.
When can I plant tomatoes in Boise?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 1 – May 8. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Boise Air Terminal, ID (USW00024131), 6.0 km (3.7 mi) from the city center, elevation 858 m, based on 27 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.