Last Frost Date

Planting planner: Idaho Falls, Idaho

Typical last spring frost May 23 (1 spring in 10 later than June 13). Typical first fall frost September 20 (1 fall in 10 earlier than September 1). Growing season about 114 days.

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Frost likely Frost possible Frost unlikely Frost is likely until May 7 and fades out by June 13. It is unlikely from then until September 1, and likely again after October 4. The dashed lines are the typical dates, May 23 and September 20.

Your season is too short for a separate fall planting of cabbage and broccoli: sown late enough to be a fall crop, it wouldn't be ready before the typical first frost. Your spring planting is your harvest.

January

Nothing to start this month.

February

Nothing to start this month.

March

  • March 7 to April 4: Broccoli and cabbage (start seeds indoors)
  • March 21 to April 18: Cauliflower (start seeds indoors)

April

  • April 4 to 25: Eggplant (start seeds indoors)
  • April 11 to 25: Peppers (start seeds indoors)
  • April 18 to May 2: Tomatoes (start seeds indoors)
  • April 25 to May 9: Peas, spinach, lettuce, radishes, onion sets, turnips (sow outdoors)
  • April 25 to May 9: Broccoli and cabbage (plant out)

May

  • May 9 to 23: Beets, carrots, potatoes, Swiss chard (plant outdoors)
  • May 9 to 23: Cauliflower (plant out)
  • May 23: Snap beans, sweet corn, cucumbers, summer squash (sow outdoors)

June

  • June 6: Tomatoes, peppers, eggplant (plant out)
  • June 6: Melons, winter squash, pumpkins, lima beans (sow outdoors)
  • June 24: Snap beans for fall (last date to sow)
  • June 28: Carrots for fall (last date to sow)
  • June 29: Cucumbers for fall (last date to sow)

July

  • July 3: Peas for fall (last date to sow)
  • July 4: Summer squash for fall (last date to sow)
  • July 8: Leaf lettuce and beets for fall (last date to sow)
  • July 18: Turnips and kohlrabi for fall (last date to sow)
  • July 28: Spinach for fall (last date to sow)

August

  • August 7: Radishes for fall (last date to sow)

September

  • September 1: Tomatoes, peppers, squash, melons, cucumbers (watch the forecast)

October

  • October 9 to 16: Garlic (plant cloves)

November

Nothing to start this month.

December

Nothing to start this month.

Dates from NOAA's 1991 to 2020 climate normals for Idaho Falls Fanning Field (station USW00024145), 2 miles from the center of Idaho Falls. Planting rules: Colorado State University Extension GardenNotes #720 (spring), Virginia Cooperative Extension 426-334 (fall crops), University of Minnesota Extension (garlic). Spring bulbs: plant when the soil has cooled to about 50 to 55°F, until a couple of weeks before the ground freezes (University of Wisconsin–Madison Extension). Full details: https://lastfrostdate.com/frost-dates/idaho/idaho-falls/

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