Idaho Falls, Idaho planting calendar and frost dates
Idaho Falls is in USDA hardiness zone 5b. The last spring frost typically comes around May 23 and the first fall frost around September 20, giving about 114 frost-free days a year.
- Hardiness zone
- Zone 5b
- Typical last frost
- May 23
- Typical first frost
- September 20
- Frost-free season
- 114 days
Frost dates in Idaho Falls
Last spring frost
- May 7Risky: frost later than this in 9 years out of 10
- May 23Typical: a later frost in half of years
- June 13Safe: a later frost only 1 year in 10
First fall frost
- September 1Risky: frost earlier than this 1 year in 10
- September 20Typical: an earlier frost in half of years
- October 4Late: frost before this in 9 years out of 10
The growing season between the typical last and first frosts is about 114 days. Frost here means a low of 32°F at the weather station. A hard freeze (28°F), which damages most hardy crops too, typically ends around May 7 and returns around October 2.
NOAA U.S. Climate Normals 1991-2020 for Idaho Falls Fanning Fld, 5.8 miles E of the city center and 174 feet lower. Low-lying and rural spots often frost later in spring and earlier in fall than airports and city centers.
What to plant each month in Idaho Falls
January
Start indoors: onions
February
Start indoors: collard greens, leeks, onions, petunias, ranunculus
March
Start indoors: black-eyed susans, broccoli, cabbages, cauliflower, chives, collard greens, ginger, kale, leeks, lettuce, marigolds, onions, oregano, parsley, peppers, petunias, ranunculus, rosemary, sage, snapdragons
April
Start indoors: basil, black-eyed susans, cabbages, cauliflower, celery, chives, cilantro, collard greens, eggplants, ginger, lettuce, marigolds, nasturtiums, peppers, ranunculus, sage, snapdragons, spinach, swiss chard, tomatoes, zinnias
Plant or sow outdoors: beets, black-eyed susans, blackberries, blueberries, broccoli, cauliflower, chives, cilantro, collard greens, figs, garlic, gladioli, grapes, grass seed, hollyhocks, kale, leeks, onions, peas, poppies, radishes, ranunculus, raspberries, rhubarb, roses, spinach, strawberries, swiss chard, turnips, wildflowers
May
Start indoors: basil, cantaloupes, cosmos, cucumbers, okra, pumpkins, ranunculus, tomatoes, watermelons, winter squash, zinnias, zucchini
Plant or sow outdoors: asparagus, beets, black-eyed susans, blackberries, broccoli, cabbages, carrots, cauliflower, chives, cilantro, collard greens, dahlias, dill, figs, garden mums, ginger, gladioli, grapes, green onions, kentucky bluegrass, lavenders, leeks, lettuce, lilies, marigolds, mints, nasturtiums, onions, oregano, parsley, perennial ryegrass, petunias, potatoes, radishes, ranunculus, rosemary, roses, sage, snapdragons, spinach, sunflowers, sweet corn, sweet peas, swiss chard, tall fescue, thyme, turnips, zinnias
June
Start indoors: cosmos, cucumbers, okra, pumpkins, winter squash, zucchini
Plant or sow outdoors: asparagus, basil, cantaloupes, cucumbers, eggplants, garden mums, ginger, grapes, green beans, green onions, kentucky bluegrass, lavenders, lilies, marigolds, mints, nasturtiums, oregano, parsley, peppers, perennial ryegrass, petunias, pumpkins, rosemary, sage, st. augustinegrass, sunflowers, sweet corn, sweet peas, tall fescue, thyme, tomatoes, watermelons, winter squash, zinnias, zucchini
Plant for fall: bearded irises, brussels sprouts, carrots, collard greens, lettuce, peas, snapdragons, swiss chard
July
Plant or sow outdoors: bermudagrass, celery, centipedegrass, cosmos, green onions, okra, peanuts, st. augustinegrass, sweet potatoes, zoysiagrass
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, carrots, cauliflower, clematis, collard greens, coneflowers, daylilies, hostas, hydrangeas, kale, lettuce, peas, radishes, roses, saffron, snapdragons, spinach, swiss chard, turnips
August
Plant or sow outdoors: bermudagrass, centipedegrass, st. augustinegrass, zoysiagrass
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, cauliflower, clematis, coneflowers, crocuses, daffodils, daylilies, grass seed, hostas, hyacinths, hydrangeas, kale, lilies, ornamental alliums, peonies, radishes, roses, saffron, spinach, tulips, turnips
September
Plant for fall: crocuses, daffodils, garlic, hyacinths, lilies, ornamental alliums, peonies, tulips
October
Plant for fall: crocuses, garlic, hyacinths, ornamental alliums, tulips
Frost dates and zones by ZIP code in Idaho Falls
Idaho Falls's 3 main ZIP codes take their frost dates from 2 different NOAA stations: the typical last frost ranges from May 23 in 83402 to June 9 in 83401. Every one of them is in zone 5b.
Planting dates for popular crops in Idaho Falls
| Plant | Start indoors | Plant or sow outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Apr 20 to May 4 | Jun 15 to 29 | — |
| Strawberries | — | Apr 11 to 25 | — |
| Lettuce | Mar 28 to Apr 11 | May 16 to 30 | Jun 21 to Jul 26 |
| Cilantro | Apr 11 to 25 | May 23 to 30 | — |
| Basil | Apr 27 to May 11 | Jun 15 to 22 | — |
| Potatoes | — | May 7 to 14 | — |
| Garlic | — | Apr 11 to 25 | Sep 20 to Oct 4 |
| Onions | Jan 31 to Mar 14 | Apr 25 to May 9 | — |
| Cucumbers | May 18 to Jun 1 | Jun 15 to 29 | — |
| Pumpkins | May 18 to Jun 1 | Jun 15 to 29 | — |
| Peppers | Mar 30 to Apr 27 | Jun 15 to 29 | — |
| Carrots | — | May 2 to 23 | Jun 28 to Jul 19 |
| Sweet Potatoes | — | Jul 3 to 10 | — |
| Watermelons | May 11 to 25 | Jun 15 to 29 | — |
| Sweet Corn | — | May 23 to Jun 6 | — |
| Green Beans | — | Jun 15 to 29 | — |
| Zucchini | May 18 to Jun 1 | Jun 15 to 29 | — |
| Broccoli | Mar 7 to 28 | Apr 25 to May 9 | Jul 5 to Aug 2 |
| Peas | — | Apr 11 to 25 | Jun 28 to Jul 12 |
| Spinach | Apr 11 to 18 | May 16 to 30 | Jul 12 to Aug 16 |
| Sunflowers | — | May 23 to Jun 13 | — |
| Zinnias | Apr 25 to May 2 | May 23 to Jun 6 | — |
| Tulips | — | — | Aug 9 to Oct 4 |
| Daffodils | — | — | Aug 9 to Sep 20 |
| Grass Seed | — | Apr 11 to 25 | Aug 9 to 23 |
Nearby cities
- Pocatello, ID zone 6a, last frost May 16
- Logan, UT zone 6a, last frost Apr 30
- Twin Falls, ID zone 6b, last frost May 9
- Ogden, UT zone 7a, last frost Apr 22
- Bozeman, MT zone 5a, last frost May 23
- Layton, UT zone 7a, last frost Apr 22
Planting in IdahoAbout zone 5bPrintable calendar for Idaho Falls
Questions
When is the last frost in Idaho Falls?
Around May 23 in a typical year, based on NOAA's 1991-2020 records for Idaho Falls Fanning Fld. There is still a 1 in 10 chance of frost after June 13.
What planting zone is Idaho Falls in?
USDA hardiness zone 5b (2023 map). The zone tells you which perennials survive the winter; planting dates depend on frost dates instead.
When should I plant tomatoes in Idaho Falls?
Start seeds indoors April 20 to May 4 and set plants out June 15 to 29.
When is the first frost in Idaho Falls?
Around September 20 in a typical year, and before September 1 about 1 year in 10.