LawnWeather

Helena, MT Planting Calendar

The last spring frost in Helena usually comes around May 10 and the first fall frost around Oct 3, a growing season of about 146 days. Start tomatoes indoors Mar 29 – Apr 12 and plant them outside May 24 – Jun 7.

Last spring frostMay 10
First fall frostOct 3
Growing season146 days

When to plant vegetables in Helena

VegetableStart seeds indoorsPlant outsideFall crop
TomatoesMar 29 – Apr 12May 24 – Jun 7—
PeppersMar 22 – Apr 5May 31 – Jun 14—
EggplantMar 22 – Apr 5May 31 – Jun 14—
Cucumbers—May 24 – Jun 7—
Zucchini & summer squash—May 24 – Jun 7—
Pumpkins & winter squash—May 31 – Jun 14—
Green beans—May 24 – Jun 7Jul 11 – Jul 25
Sweet corn—May 24 – Jun 7—
BasilApr 12 – Apr 26May 24 – Jun 7—
LettuceMar 15 – Mar 29Apr 12 – May 24Aug 8 – Aug 22
Spinach—Mar 29 – Apr 19Aug 8 – Aug 22
Peas—Mar 29 – Apr 19Jul 25 – Aug 8
Carrots—Apr 12 – May 17Jul 11 – Jul 25
Radishes—Apr 5 – May 24Aug 22 – Sep 5
BroccoliMar 1 – Mar 15Apr 12 – Apr 26Jul 11 – Jul 25
KaleMar 15 – Mar 29Apr 5 – Apr 19Jul 25 – Aug 8
Onions—Apr 12 – Apr 26—
Potatoes—Apr 19 – May 17—
Garlic——Sep 19 – Oct 24

Dates count from the median frost dates (2016–2025) for Helena. In a cold spring, wait a week; in a warm one you can go a week early.

Month-by-month planting in Helena

  1. JanuaryPlan, order seeds and prepare beds.
  2. FebruaryPlan, order seeds and prepare beds.
  3. MarchStart indoors: Tomatoes, Peppers, Eggplant, Lettuce, Broccoli, KalePlant outside: Spinach, Peas
  4. AprilStart indoors: Tomatoes, Peppers, Eggplant, BasilPlant outside: Lettuce, Spinach, Peas, Carrots, Radishes, Broccoli, Kale, Onions, Potatoes
  5. MayPlant outside: Tomatoes, Peppers, Eggplant, Cucumbers, Zucchini & summer squash, Pumpkins & winter squash, Green beans, Sweet corn, Basil, Lettuce, Carrots, Radishes, Potatoes
  6. JunePlant outside: Tomatoes, Peppers, Eggplant, Cucumbers, Zucchini & summer squash, Pumpkins & winter squash, Green beans, Sweet corn, Basil
  7. JulyPlant outside: Green beans, Peas, Carrots, Broccoli, Kale
  8. AugustPlant outside: Lettuce, Spinach, Peas, Radishes, Kale
  9. SeptemberPlant outside: Radishes, Garlic
  10. OctoberPlant outside: Garlic
  11. NovemberPlan, order seeds and prepare beds.
  12. DecemberPlan, order seeds and prepare beds.

Tools for this season

Seed starting kitTrays with humidity domes for starting seeds indoors.See options on AmazonLED grow lightKeeps indoor seedlings short and sturdy.See options on AmazonFrost clothCovers tender plants on a surprise frost night.See options on AmazonSoil thermometerCheck the soil at 4 inches before you spread anything.See options on Amazon

We may earn a commission when you buy through these links, at no extra cost to you. How this works

Frequently asked questions

When is the last frost in Helena?

The median last spring frost is May 10 and the median first fall frost is Oct 3, based on 2016–2025 weather data.

When should I plant tomatoes in Helena?

Start seeds indoors Mar 29 – Apr 12 and set plants outside May 24 – Jun 7, once nights stay above 50°F.

When should I plant a fall garden in Helena?

Sow or transplant cool-season crops 6 to 12 weeks before the first fall frost (around Oct 3): broccoli and carrots first, lettuce, spinach and radishes last.

More from Helena