Last Frost Date

Planting planner: Denver, Colorado

Typical last spring frost May 4 (1 spring in 10 later than May 16). Typical first fall frost October 8 (1 fall in 10 earlier than September 25). Growing season about 156 days.

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Frost likely Frost possible Frost unlikely Frost is likely until April 20 and fades out by May 16. It is unlikely from then until September 25, and likely again after October 20. The dashed lines are the typical dates, May 4 and October 8.

Your season is too short for a separate fall planting of cabbage: 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

  • February 16 to March 16: Broccoli and cabbage (start seeds indoors)

March

  • March 2 to 30: Cauliflower (start seeds indoors)
  • March 16 to April 6: Eggplant (start seeds indoors)
  • March 23 to April 6: Peppers (start seeds indoors)
  • March 30 to April 13: Tomatoes (start seeds indoors)

April

  • April 6 to 20: Peas, spinach, lettuce, radishes, onion sets, turnips (sow outdoors)
  • April 6 to 20: Broccoli and cabbage (plant out)
  • April 20 to May 4: Beets, carrots, potatoes, Swiss chard (plant outdoors)
  • April 20 to May 4: Cauliflower (plant out)

May

  • May 4: Snap beans, sweet corn, cucumbers, summer squash (sow outdoors)
  • May 18: Tomatoes, peppers, eggplant (plant out)
  • May 18: Melons, winter squash, pumpkins, lima beans (sow outdoors)

June

  • June 2 to 16: Broccoli for fall (start seeds)

July

  • July 12: Snap beans for fall (last date to sow)
  • July 16: Carrots for fall (last date to sow)
  • July 17: Cucumbers for fall (last date to sow)
  • July 21: Peas for fall (last date to sow)
  • July 22: Summer squash for fall (last date to sow)
  • July 26: Leaf lettuce and beets for fall (last date to sow)

August

  • August 5: Turnips and kohlrabi for fall (last date to sow)
  • August 15: Spinach for fall (last date to sow)
  • August 25: Radishes for fall (last date to sow)

September

  • September 25: Tomatoes, peppers, squash, melons, cucumbers (watch the forecast)

October

  • October 25 to November 1: 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 Denver-Stapleton (station USW00023062), less than a mile from the center of Denver. 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/colorado/denver/

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