Lewiston, ID planting zone & frost dates
Lewiston is in USDA hardiness zone 7a. The last spring frost usually comes around April 6 and the first fall frost around October 26, for a growing season of about 200 days.
Planting calendar for Lewiston
Dates are counted from the average last spring frost (April 6) 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 9 – Feb 23 Transplant outdoors: Apr 13 – Apr 20 |
| Peppers | Start seeds indoors: Jan 26 – Feb 9 Transplant outdoors: Apr 20 – Apr 27 |
| Eggplant | Start seeds indoors: Jan 26 – Feb 9 Transplant outdoors: Apr 20 – Apr 27 |
| Broccoli | Start seeds indoors: Jan 26 – Feb 9 Transplant outdoors: Mar 9 – Mar 23 |
| Cabbage | Start seeds indoors: Jan 26 – Feb 9 Transplant outdoors: Mar 9 – Mar 23 |
| Onions (sets) | Plant outdoors: Mar 9 – Mar 23 |
| Peas | Sow outdoors: Feb 23 – Mar 9 |
| Spinach | Sow outdoors: Feb 23 – Mar 9 |
| Lettuce | Sow outdoors: Mar 9 – Mar 23 |
| Carrots | Sow outdoors: Mar 9 – Mar 23 |
| Potatoes | Plant outdoors: Mar 9 – Mar 23 |
| Beans | Sow outdoors: Apr 13 – Apr 20 |
| Sweet corn | Sow outdoors: Apr 13 – Apr 20 |
| Cucumbers | Sow outdoors: Apr 13 – Apr 20 |
| Squash & zucchini | Sow outdoors: Apr 13 – Apr 20 |
| Basil | Start seeds indoors: Feb 23 – Mar 9 Transplant outdoors: Apr 13 – Apr 20 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 31 (8 weeks before the average first fall frost on Oct 26).
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 | Mar 20 | Apr 6 | Apr 26 |
| First 32°F frost in fall is before | Nov 12 | Oct 26 | Oct 10 |
How to read it: in spring there is a 10% chance of a frost after April 26, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 10. A hard freeze (28°F) usually ends around March 15.
Hardiness zone by ZIP code in Lewiston
- 83501 zone 7b
Nearby cities
- Lewiston Orchards zone 7b, last frost Apr 6
- Moscow zone 6b, last frost Apr 29
- Coeur d'Alene zone 7a, last frost Apr 22
- Post Falls zone 6b, last frost Apr 22
- Hayden zone 6b, last frost Apr 22
- Eagle Foothills zone 7a, last frost Apr 30
- Caldwell zone 7a, last frost Apr 23
- Eagle zone 7a, last frost Apr 24
Questions
What growing zone is Lewiston, ID?
Lewiston 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 7b.
When is the last frost in Lewiston?
The average last spring frost (32°F) in Lewiston is April 6. There is still a 10% chance of frost until April 26.
When can I plant tomatoes in Lewiston?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 13 – Apr 20. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Lewiston Nez Perce Co Ap, ID (USW00024149), 4.7 km (2.9 mi) from the city center, elevation 438 m, based on 28 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.