Twin Falls, Idaho planting calendar and frost dates
Twin Falls is in USDA hardiness zone 6b. The last spring frost typically comes around May 9 and the first fall frost around October 4, giving about 147 frost-free days a year.
- Hardiness zone
- Zone 6b
- Typical last frost
- May 9
- Typical first frost
- October 4
- Frost-free season
- 147 days
Frost dates in Twin Falls
Last spring frost
- April 25Risky: frost later than this in 9 years out of 10
- May 9Typical: a later frost in half of years
- May 28Safe: a later frost only 1 year in 10
First fall frost
- September 20Risky: frost earlier than this 1 year in 10
- October 4Typical: an earlier frost in half of years
- October 20Late: frost before this in 9 years out of 10
The growing season between the typical last and first frosts is about 147 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 April 25 and returns around October 15.
NOAA U.S. Climate Normals 1991-2020 for Twin Falls Sun Vly Rgnl Airport, 5.9 miles NNE of the city center and 196 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 Twin Falls
January
Start indoors: onions
February
Start indoors: broccoli, cabbages, cauliflower, collard greens, kale, leeks, onions, oregano, parsley, petunias, ranunculus, rosemary, snapdragons
March
Start indoors: black-eyed susans, broccoli, cabbages, cauliflower, celery, chives, cilantro, collard greens, ginger, kale, leeks, lettuce, marigolds, nasturtiums, oregano, parsley, peppers, petunias, ranunculus, rosemary, sage, snapdragons, spinach, swiss chard
Plant or sow outdoors: black-eyed susans, blueberries, garlic, grapes, grass seed, hollyhocks, onions, peas, poppies, raspberries, rhubarb, strawberries, turnips, wildflowers
April
Start indoors: basil, cantaloupes, celery, cilantro, eggplants, marigolds, nasturtiums, peppers, ranunculus, spinach, swiss chard, tomatoes, watermelons
Plant or sow outdoors: asparagus, beets, black-eyed susans, blackberries, blueberries, broccoli, cabbages, carrots, cauliflower, chives, cilantro, collard greens, dahlias, dill, figs, garlic, gladioli, grapes, grass seed, green onions, hollyhocks, kale, leeks, lettuce, onions, parsley, peas, poppies, potatoes, radishes, ranunculus, raspberries, rhubarb, roses, snapdragons, spinach, strawberries, swiss chard, turnips, wildflowers
May
Start indoors: cantaloupes, cosmos, cucumbers, okra, pumpkins, watermelons, winter squash, zucchini
Plant or sow outdoors: asparagus, beets, carrots, cauliflower, chives, cilantro, dahlias, dill, figs, garden mums, ginger, gladioli, grapes, green onions, kentucky bluegrass, lavenders, leeks, lettuce, lilies, marigolds, mints, nasturtiums, oregano, parsley, perennial ryegrass, petunias, potatoes, ranunculus, rosemary, roses, sage, snapdragons, spinach, sunflowers, sweet corn, sweet peas, swiss chard, tall fescue, thyme
June
Start indoors: zinnias
Plant or sow outdoors: asparagus, basil, bermudagrass, cantaloupes, celery, centipedegrass, cosmos, cucumbers, eggplants, garden mums, green beans, green onions, okra, peanuts, peppers, pumpkins, st. augustinegrass, sweet potatoes, tomatoes, watermelons, winter squash, zoysiagrass, zucchini
Plant for fall: brussels sprouts
July
Plant or sow outdoors: bermudagrass, celery, centipedegrass, cosmos, green onions, okra, peanuts, st. augustinegrass, zinnias, zoysiagrass
Plant for fall: bearded irises, beets, broccoli, brussels sprouts, cabbages, carrots, cauliflower, collard greens, lettuce, peas, radishes, snapdragons, spinach, swiss chard, turnips
August
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, carrots, cauliflower, clematis, coneflowers, crocuses, daffodils, daylilies, grass seed, hostas, hydrangeas, kale, lettuce, lilies, ornamental alliums, peonies, radishes, roses, saffron, snapdragons, spinach, swiss chard, tulips, turnips
September
Plant for fall: crocuses, daffodils, daylilies, grass seed, hostas, hyacinths, kale, lilies, ornamental alliums, peonies, radishes, saffron, tulips
October
Plant for fall: crocuses, daffodils, garlic, hyacinths, lilies, ornamental alliums, peonies, tulips
Frost dates and zones by ZIP code in Twin Falls
All 2 of Twin Falls's main ZIP codes take their frost dates from Twin Falls Sun Vly Rgnl Airport, so the dates on this page apply across the city. Every one of them is in zone 6b.
Planting dates for popular crops in Twin Falls
| Plant | Start indoors | Plant or sow outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Apr 8 to 22 | Jun 3 to 17 | — |
| Strawberries | — | Mar 28 to Apr 11 | — |
| Lettuce | Mar 14 to 28 | May 2 to 16 | Jul 5 to Aug 9 |
| Cilantro | Mar 28 to Apr 11 | May 9 to 16 | — |
| Basil | Apr 15 to 29 | Jun 3 to 10 | — |
| Potatoes | — | Apr 29 to May 6 | — |
| Garlic | — | Mar 28 to Apr 11 | Oct 4 to 18 |
| Onions | Jan 17 to Feb 28 | Apr 11 to 25 | — |
| Cucumbers | May 6 to 20 | Jun 3 to 17 | — |
| Pumpkins | May 6 to 20 | Jun 3 to 17 | — |
| Peppers | Mar 18 to Apr 15 | Jun 3 to 17 | — |
| Carrots | — | Apr 18 to May 9 | Jul 12 to Aug 2 |
| Sweet Potatoes | — | Jun 20 to 27 | — |
| Watermelons | Apr 29 to May 13 | Jun 3 to 17 | — |
| Sweet Corn | — | May 9 to 23 | — |
| Green Beans | — | Jun 3 to 17 | — |
| Zucchini | May 6 to 20 | Jun 3 to 17 | — |
| Broccoli | Feb 21 to Mar 14 | Apr 11 to 25 | Jul 19 to Aug 16 |
| Peas | — | Mar 28 to Apr 11 | Jul 12 to 26 |
| Spinach | Mar 28 to Apr 4 | May 2 to 16 | Jul 26 to Aug 30 |
| Sunflowers | — | May 9 to 30 | — |
| Zinnias | Jun 6 to 13 | Jul 4 to 18 | — |
| Tulips | — | — | Aug 23 to Oct 18 |
| Daffodils | — | — | Aug 23 to Oct 4 |
| Grass Seed | — | Mar 28 to Apr 11 | Aug 23 to Sep 6 |
Nearby cities
- Pocatello, ID zone 6a, last frost May 16
- Boise City, ID zone 6b, last frost Apr 24
- Meridian, ID zone 7a, last frost Apr 24
- Nampa, ID zone 7a, last frost Apr 24
- Caldwell, ID zone 7a, last frost Apr 29
- Idaho Falls, ID zone 5b, last frost May 23
Planting in IdahoAbout zone 6bPrintable calendar for Twin Falls
Questions
When is the last frost in Twin Falls?
Around May 9 in a typical year, based on NOAA's 1991-2020 records for Twin Falls Sun Vly Rgnl Airport. There is still a 1 in 10 chance of frost after May 28.
What planting zone is Twin Falls in?
USDA hardiness zone 6b (2023 map). The zone tells you which perennials survive the winter; planting dates depend on frost dates instead.
When should I plant tomatoes in Twin Falls?
Start seeds indoors April 8 to 22 and set plants out June 3 to 17.
When is the first frost in Twin Falls?
Around October 4 in a typical year, and before September 20 about 1 year in 10.