Frost Dates for Idaho Falls, ID 83401
Last spring frost June 12 · First fall frost September 5 · 85 frost-free days · USDA Zone 5b
ZIP 83401 has about 48,000 people, the largest of 4 ZIP codes in Idaho Falls.
Short season: 85 frost-free days. Spring frost risk spans May 19–July 6 (48 days). Fall frost risk spans August 16–September 25 (40 days).
Frost probability for 83401
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | July 6 | June 12 | May 19 |
| Fall (first frost) | August 16 | September 5 | September 25 |
Dates come from NOAA 1971–2000 freeze probabilities at SAINT ANTHONY (49.0 km away); the 50% date is the median year.
Frost dates by ZIP code in Idaho Falls, ID
| ZIP | Last spring frost (50%) | First fall frost (50%) | Zone |
|---|---|---|---|
| 83401 | June 12 | September 5 | 5b |
| 83402 | May 28 | September 18 | 5b |
| 83404 | May 28 | September 18 | 5b |
| 83406 | May 28 | September 18 | 5b |
Which crops fit a 85-day season in Idaho Falls
In Idaho Falls (85 frost-free days, a short season), 28 of 56 planner crops fit outright, 12 get two plantings, 3 need an indoor start, 1 need a faster variety, 11 don't reliably mature, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | May 8 | Jun 26–Jul 3 | 43 | no-fit: Needs 80 days; Idaho Falls has 43 after Jun 26. | — |
| Pepper | May 1 | Jun 26–Jul 3 | 43 | no-fit: Needs 75 days; Idaho Falls has 43 after Jun 26. | — |
| Lettuce | Apr 17 | May 15–May 22 | 120 | two-plantings: Plant May 15 and again by Jul 15; both mature before Sep 12. | Jul 15 |
| Carrots | — | May 22–May 29 | 127 | fits: 70 days to maturity, 127 available after May 22. | Jul 4 |
| Cucumber | May 22 | Jun 26–Jul 3 | 57 | head-start: Even planted out Jun 26, the outdoor season is about 3 days short; choose an early variety or grow under cover. | — |
| Beans | — | Jun 19–Jul 3 | 71 | fits: 60 days to maturity, 71 available after Jun 19. | — |
| Peas | — | Apr 17–Jun 26 | 148 | fits: 65 days to maturity, 148 available after Apr 17. | Jun 25 |
| Zucchini | May 29 | Jun 26–Jul 3 | 57 | fits: 55 days to maturity, 57 available after Jun 26. | — |
| Onion | Mar 20 | May 15–May 29 | 120 | fits: 100 days to maturity, 120 available after May 15. | — |
| Spinach | — | Apr 17–Jun 5 | 162 | two-plantings: Plant Apr 17 and again by Aug 3; both mature before Sep 26. | Aug 3 |
| Kale | Apr 3 | May 15–May 29 | 134 | two-plantings: Plant May 15 and again by Jul 19; both mature before Sep 26. | Jul 19 |
| Broccoli | Apr 17 | May 15–May 29 | 120 | fits: 80 days to maturity, 120 available after May 15. | Jun 10 |
| Cabbage | Apr 17 | May 15–May 29 | 134 | fits: 70 days to maturity, 134 available after May 15. | Jul 4 |
| Radish | — | Apr 17–Jul 10 | 148 | two-plantings: Plant Apr 17 and again by Aug 4; both mature before Sep 12. | Aug 4 |
| Beets | — | Apr 17–Jul 10 | 148 | two-plantings: Plant Apr 17 and again by Jul 5; both mature before Sep 12. | Jul 5 |
| Potatoes | — | May 29–Jun 5 | 106 | fits: 90 days to maturity, 106 available after May 29. | — |
| Garlic | — | Sep 5 | 190 | overwinter: Plant Sep 5 to Sep 26; harvest the following summer. | Sep 26 |
| Strawberry | — | May 8–Jul 3 | 141 | perennial: A perennial: plant May 8; it fruits from the following year and keeps producing for several years. | — |
| Corn | May 15 | Jun 19–Jun 26 | 57 | head-start: Even planted out Jun 19, the outdoor season is about 18 days short; choose an early variety or grow under cover. | — |
| Pumpkin | May 29 | Jun 26–Jun 26 | 50 | no-fit: Needs 100 days; Idaho Falls has 50 after Jun 26. | — |
| Cauliflower | May 1 | Jun 5–Jun 19 | 99 | fits: 75 days to maturity, 99 available after Jun 5. | Jun 15 |
| Swiss Chard | Apr 17 | May 29–May 29 | 106 | fits: 55 days to maturity, 106 available after May 29. | Jul 5 |
| Arugula | — | Apr 17–Jul 10 | 162 | two-plantings: Plant Apr 17 and again by Aug 3; both mature before Sep 26. | Aug 3 |
| Brussel Sprouts | Apr 17 | May 15–May 29 | 134 | fits: 100 days to maturity, 134 available after May 15. | Jun 4 |
| Butternut Squash | May 29 | Jun 26–Jul 3 | 50 | no-fit: Needs 100 days; Idaho Falls has 50 after Jun 26. | — |
| Eggplant | Apr 24 | Jun 26–Jul 3 | 43 | no-fit: Needs 70 days; Idaho Falls has 43 after Jun 26. | — |
| Okra | May 15 | Jun 19–Jun 26 | 64 | fits: 55 days to maturity, 64 available after Jun 19. | — |
| Basil | May 8 | Jul 3–Jul 3 | 50 | head-start: Even planted out Jul 3, the outdoor season is about 10 days short; choose an early variety or grow under cover. | — |
| Cilantro | — | May 15–Jun 5 | 120 | two-plantings: Plant May 15 and again by Jul 10; both mature before Sep 12. | Jul 10 |
| Parsley | Apr 3 | Jun 19–Jun 26 | 85 | fits: 70 days to maturity, 85 available after Jun 19. | Jun 20 |
| Celery | Apr 3 | Jun 19–Jul 3 | 85 | no-fit: Needs 120 days; Idaho Falls has 85 after Jun 19. | — |
| Scallions | Apr 3 | May 15–May 29 | 134 | two-plantings: Plant May 15 and again by Jul 14; both mature before Sep 26. | Jul 14 |
| Turnip | — | May 15–May 29 | 134 | two-plantings: Plant May 15 and again by Jul 24; both mature before Sep 26. | Jul 24 |
| Kohlrabi | — | May 1–May 15 | 148 | two-plantings: Plant May 1 and again by Jul 19; both mature before Sep 26. | Jul 19 |
| Bok Choy | May 15 | Jun 5–Jun 12 | 99 | fits: 45 days to maturity, 99 available after Jun 5. | Jul 15 |
| Collards | Apr 3 | May 15–May 29 | 134 | two-plantings: Plant May 15 and again by Jul 14; both mature before Sep 26. | Jul 14 |
| Cantaloupe | May 29 | Jun 26–Jul 3 | 43 | no-fit: Needs 85 days; Idaho Falls has 43 after Jun 26. | — |
| Chives | Mar 20 | Jun 19–Jun 26 | 99 | fits: 90 days to maturity, 99 available after Jun 19. | — |
| Dill | — | Apr 17–Jul 10 | 148 | two-plantings: Plant Apr 17 and again by Jul 5; both mature before Sep 12. | Jul 5 |
| Oregano | Apr 3 | Jun 19–Jun 26 | 99 | fits: 80 days to maturity, 99 available after Jun 19. | — |
| Rosemary | Mar 20 | Jun 19–Jun 26 | 85 | fits: 80 days to maturity, 85 available after Jun 19. | — |
| Sage | Apr 17 | Jun 19–Jun 26 | 99 | fits: 75 days to maturity, 99 available after Jun 19. | — |
| Thyme | Apr 3 | Jun 19–Jun 26 | 99 | fits: 90 days to maturity, 99 available after Jun 19. | — |
| Calendula | May 1 | May 29–Jun 12 | 106 | fits: 50 days to maturity, 106 available after May 29. | Jul 10 |
| Cosmos | May 15 | Jun 12–Jun 26 | 71 | fits: 60 days to maturity, 71 available after Jun 12. | — |
| Lavender | Mar 20 | Jun 12–Jun 26 | 106 | fits: 90 days to maturity, 106 available after Jun 12. | — |
| Marigolds | May 1 | Jun 12–Jun 19 | 71 | fits: 50 days to maturity, 71 available after Jun 12. | Jun 19 |
| Melons | May 29 | Jun 26–Jul 3 | 43 | no-fit: Needs 85 days; Idaho Falls has 43 after Jun 26. | — |
| Mint | — | Jun 12–Jun 26 | 106 | fits: 90 days to maturity, 106 available after Jun 12. | — |
| Nasturtiums | May 15 | Jun 12–Jun 19 | 71 | fits: 55 days to maturity, 71 available after Jun 12. | Jun 14 |
| Pole Beans | — | Jun 19–Jul 3 | 64 | tight: Direct-sow only; pick a variety under 64 days. | — |
| Spaghetti Squash | May 29 | Jun 26–Jul 3 | 50 | no-fit: Needs 90 days; Idaho Falls has 50 after Jun 26. | — |
| Sunflowers | — | Jun 12–Jun 26 | 71 | fits: 70 days to maturity, 71 available after Jun 12. | — |
| Tomatillos | Apr 17 | Jun 19–Jun 26 | 50 | no-fit: Needs 75 days; Idaho Falls has 50 after Jun 19. | — |
| Watermelon | May 29 | Jun 19–Jun 26 | 50 | no-fit: Needs 80 days; Idaho Falls has 50 after Jun 19. | — |
| Yellow Squash | May 29 | Jun 26–Jul 3 | 57 | fits: 55 days to maturity, 57 available after Jun 26. | — |
| Zinnias | May 15 | Jun 12–Jun 26 | 71 | fits: 60 days to maturity, 71 available after Jun 12. | — |
Month by month in Idaho Falls
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start the slowest-growing crops indoors: onions, leeks, and celery (10–12 weeks before last frost). |
| March | Start indoors: Chives (Mar 20), Lavender (Mar 20), Onion (Mar 20), Rosemary (Mar 20). |
| April | Start indoors: Celery (Apr 3), Collards (Apr 3), Kale (Apr 3), Oregano (Apr 3), Parsley (Apr 3), Scallions (Apr 3), +9 more. Direct sow from: Arugula (Apr 17), Beets (Apr 17), Dill (Apr 17), Peas (Apr 17), Radish (Apr 17), Spinach (Apr 17). |
| May | Start indoors: Calendula (May 1), Cauliflower (May 1), Marigolds (May 1), Pepper (May 1), Basil (May 8), Tomato (May 8), +15 more. Direct sow from: Kohlrabi (May 1), Cilantro (May 15), Turnip (May 15), Carrots (May 22), Potatoes (May 29). Transplant from: Broccoli (May 15), Brussel Sprouts (May 15), Cabbage (May 15), Collards (May 15), Kale (May 15), Lettuce (May 15), +4 more. Plant: Strawberry (May 8). |
| June | Direct sow from: Sunflowers (Jun 12), Beans (Jun 19), Pole Beans (Jun 19). Transplant from: Bok Choy (Jun 5), Cauliflower (Jun 5), Cosmos (Jun 12), Lavender (Jun 12), Marigolds (Jun 12), Mint (Jun 12), +24 more. Last frost around June 12. Last sowing dates: Brussel Sprouts (Jun 4), Broccoli (Jun 10), Nasturtiums (Jun 14), Cauliflower (Jun 15), Marigolds (Jun 19), Parsley (Jun 20), +1 more. |
| July | Transplant from: Basil (Jul 3). Last sowing dates: Cabbage (Jul 4), Carrots (Jul 4), Beets (Jul 5), Dill (Jul 5), Swiss Chard (Jul 5), Calendula (Jul 10), +8 more. |
| August | Last sowing dates: Arugula (Aug 3), Spinach (Aug 3), Radish (Aug 4). |
| September | Direct sow from: Garlic (Sep 5). First frost around September 5. Last sowing dates: Garlic (Sep 26). |
| October | Harvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year. |
| November | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
| December | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
Frequently Asked Questions
What is the last frost date for Idaho Falls, ID (ZIP 83401)?
The median last spring frost date for Idaho Falls, ID (ZIP code 83401) is around June 12. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area. One year in ten frost ends before May 19; one in ten it runs past July 6.
What is the first fall frost date in Idaho Falls, ID?
The median first fall frost date for Idaho Falls, ID is around September 5. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses. The first frost arrives around August 16 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Idaho Falls, ID?
The frost-free growing season in Idaho Falls is about 85 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side. In Idaho Falls (85 frost-free days, a short season), 28 of 56 planner crops fit outright, 12 get two plantings, 3 need an indoor start, 1 need a faster variety, 11 don't reliably mature, 1 crop is perennial.
What USDA hardiness zone is Idaho Falls, ID?
Idaho Falls, ID is in USDA hardiness zone 5b (2023 USDA Plant Hardiness Zone Map). Zones come from the average coldest winter temperature, so they tell you which perennials survive the winter; the frost dates on this page tell you when to plant.
When should I start tomatoes indoors in Idaho Falls, ID?
Start tomatoes indoors May 8 and plant out Jun 26 in Idaho Falls. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Idaho Falls?
Two: plant May 15 and again by Jul 15; both mature before Sep 12.
When do I plant garlic in Idaho Falls?
Sep 5 to Sep 26; it overwinters and is ready the following summer.
Can I grow Celery in Idaho Falls?
Not reliably outdoors. Needs 120 days; Idaho Falls has 85 after Jun 19.
Which nearby ZIP has a longer season?
Shelley (ZIP 83274) has 113 frost-free days, 28 more than Idaho Falls (ZIP 83401). See Shelley ZIP 83274 frost dates
Nearby and related
- Frost dates for Rigby, ID 83442 (7 mi)
- Frost dates for Shelley, ID 83274 (17.1 mi)
- Frost dates for Rexburg, ID 83440 (19.4 mi)
- Frost dates for Blackfoot, ID 83221 (36.8 mi)
- Frost dates for Pocatello, ID 83201 (51.4 mi)
- When to plant in Idaho Falls, ID: month-by-month guide
- When to plant in ID
- When to plant Beets in ID
- When to plant Broccoli in ID
- When to plant Carrots in ID
- When to plant Kale in ID
- When to plant Onions in ID
- When to plant Peas in ID
- Look up another ZIP