What to plant this week in Great Falls, MT
With last frost historically around May 12, Great Falls gardeners are in the thick of late spring and early summer planting. This week marks a critical transition where cool-season crops like Brussels sprouts and leeks mature for harvest while warm-weather favorites like basil and peppers thrive under our short but intense growing season.
The next 7 days
Great Falls, MTGrowing in Great Falls right now
- Our deep glacial loess soils in Lewis and Clark County are prone to compaction; till lightly to avoid breaking up the root zone of transplants like zucchini and melons.
- With an average first frost date of October 1, prioritize immediate harvests for cantaloupe, honeydew, and summer squash before the rapid drop in temperatures halts growth.
- The region's low humidity combined with strong continental winds requires staking tall varieties like sunflowers and pole beans to prevent lodging during sudden gusts.
- Soil moisture retention is poor here due to high evaporation rates; apply mulch heavily around potato beds and beehive squash to conserve water.
Sow this week
No direct sowing windows open this week.
Transplant this week
Nothing is due to go out this week.
Harvest soon
50 crops- Basil
- Beefsteak Tomato
- Bell Pepper
- Borage
- Brussels Sprouts
- Bush Bean
- Cantaloupe
- Celery
- Cleome (Spider Flower)
- Cosmos
- Cowpea (Black-Eyed Pea)
- Cucumber
- Dahlia
- Edamame
- Eggplant
- Fennel
- Flour Corn
- French Marigold
- Garden Geranium (Zonal)
- Garden Verbena
- Garlic
- Habanero Pepper
- Honeydew Melon
- Jalapeño
- Lantana
- Leek
- Lima Bean
- Loofah (Luffa)
- Marconi Pepper
- Nasturtium
- Ornamental Sweet Potato Vine
- Parsnip
- Petunia
- Pole Bean
- Potato
- Pumpkin
- Rutabaga
- Scarlet Runner Bean
- Shiso (Japanese Basil)
- Summer Savory
- Sunflower
- Sweet Corn
- Thai Basil
- Tomatillo
- Vinca (Madagascar Periwinkle)
- Watermelon
- Winter Squash
- Yellow Summer Squash
- Zinnia
- Zucchini
Seasonal tips
- Finish succession planting bush beans and pole beans to extend the summer harvest window.
- Apply a thick layer of compost around root vegetables like parsnips and rutabagas as they mature.
- Deadhead spent flowers on zinnias, cosmos, and marigolds to encourage more blooms all season long.
Pest & disease watch
- Monitor for aphids on young tomato plants, which thrive in our fluctuating spring temperatures before the heat of June arrives.
- Watch for cutworms damaging transplanted peppers and eggplant seedlings just as they emerge from the soil.
- Scout for powdery mildew on basil and celery leaves, especially during dry, windy afternoons common to the Flathead Valley.
Watering this week
Water deeply at the soil line in the morning to prevent fungal issues on these thirsty summer crops.
Don't forget to save seeds from your favorite varieties like Beefsteak Tomato or Yellow Summer Squash before they ripen fully this week.
Great Falls gardening questions
3When is the safest time to plant my summer squash seeds outdoors in Great Falls?
Given our last frost average of May 12, wait until mid-May before planting zucchini and yellow summer squash directly in the garden. Starting them indoors a few weeks earlier ensures they are robust enough to handle our brief growing window.
Can I harvest my garlic now or should I wait longer?
Your garlic is likely bulbing but not ready for full harvest; wait until early June when leaves begin to yellow and fall over naturally. Pulling too soon results in smaller bulbs, so monitor the foliage closely as we approach the peak summer heat.
How do I protect my basil from bolting before October 1?
To extend your basil harvest through our short season, choose varieties like Thai or Shiso which are more heat-tolerant and slower to bolt. Pinch off flower buds immediately when they appear to encourage leaf production for that final summer meal.
Other cities in zone 4b
3See the full zone 4b guide → · Plan your Great Falls garden in SproutGuide →