When to plant in Idaho Falls, ID
USDA Zone 5bIdaho Falls, Idaho frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
In zone 5b, Idaho Falls gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
The average last spring frost in Idaho Falls is now 8 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
IDAHO FALLS - KIFI · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Idaho Falls’s own odds, recorded at IDAHO FALLS - KIFI.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Jun 16 | May 30 | May 10 | Sep 4 | Sep 20 | Oct 3 |
| 32°F | Jun 2 | May 9 | Apr 27 | Sep 17 | Oct 1 | Oct 15 |
| 28°F | May 11 | Apr 28 | Apr 11 | Sep 27 | Oct 13 | Oct 27 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Idaho Falls, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 23 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Idaho Falls planting FAQ
When is the last spring frost in Idaho Falls, ID?
Idaho Falls's average last spring frost falls near May 9 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Idaho Falls, ID?
Expect Idaho Falls's first fall frost near October 1 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Idaho Falls in?
Idaho Falls is in USDA hardiness zone 5b. In zone 5b, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Idaho Falls?
Idaho Falls has about 145 frost-free days — a short growing season — between the average last spring frost (May 9) and first fall frost (October 1).
When should I plant tomatoes in Idaho Falls?
For Idaho Falls, sow tomatoes indoors about March 14–March 28 and move the seedlings out around May 16, after the last spring frost.
Never miss a window in Idaho Falls
An email when it’s time to start seeds, transplant, and sow — timed to Idaho Falls’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at IDAHO FALLS - KIFI, 3 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Idaho Falls, ID — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00104455. Retrieved from https://blissgarden.com/idaho/idaho-falls.