What to plant this week in Great Falls, MT
Great Falls gardeners are officially in the harvest sprint as October 1st looms, marking your average first frost date for this Zone 4b valley. With nights already dropping toward -25°F minimums, it is critical to bring all listed crops like tomatoes and peppers indoors immediately rather than waiting another week.
The next 7 days
Great Falls, MTGrowing in Great Falls right now
- The Missouri River Valley creates distinct cold-air drainage pockets where frost settles faster on the flat ground; plant windbreaks of Fennel or Borage around your perimeter to protect late-season Kale and Collard Greens from rapid chilling.
- Soil in this specific area often retains moisture longer than surrounding ridges, which can rot roots during fall freezes; ensure you have raised beds for any remaining transplants like Sweet Corn or Zucchini to improve drainage before the ground locks up.
- Take advantage of the extended daylight hours typical of Montana's latitude to get a final harvest on Scarlet Runner Beans and Pole Beans before the first hard freeze halts growth entirely.
Sow this week
No direct sowing windows open this week.
Transplant this week
Nothing is due to go out this week.
Harvest soon
46 crops- Bachelor's Button (Cornflower)
- Basil
- Beet
- Bell Pepper
- Borage
- Bush Bean
- Cabbage
- Carrot
- Cauliflower
- Cherry Tomato
- Cleome (Spider Flower)
- Collard Greens
- Cosmos
- Cowpea (Black-Eyed Pea)
- Cucumber
- Dill
- Fava (Broad) Bean
- Fennel
- French Marigold
- Garlic
- German Chamomile
- Ground Cherry
- Kale
- Napa Cabbage
- Nasturtium
- Onion
- Ornamental Sweet Potato Vine
- Pansy
- Parsley
- Pole Bean
- Potato
- Rutabaga
- Scallion (Bunching Onion)
- Scarlet Runner Bean
- Shallot
- Shishito Pepper
- Snapdragon
- Summer Savory
- Sweet Corn
- Swiss Chard
- Thai Basil
- Tomato
- Vinca (Madagascar Periwinkle)
- Yellow Summer Squash
- Zinnia
- Zucchini
Seasonal tips
- Succession sow snap beans or Swiss chard every two weeks to ensure a continuous harvest through summer.
- Mulch around newly transplanted peppers and tomatoes with straw to retain soil moisture and keep roots cool as temperatures rise.
- Thin out carrot tops gently if they are overcrowded to allow the remaining plants to bulge up nicely for harvest.
- Stake tall crops like sweet corn, pole beans, and indeterminate tomato varieties now before heavy winds arrive.
Pest & disease watch
- Late-season fungal blight is active on the abundant moisture-loving crops like Cucumber, Squash, and Tomato; apply copper fungicides now as temperatures cool but humidity remains high.
- Cutworms often emerge in early fall to eat seedling stems of Swiss Chard and Lettuce; check soil lines nightly and hand-pick them before they sever the stalks.
Watering this week
Water deeply at soil level in the morning to prevent fungal issues while ensuring thirsty crops like corn and beans get consistent moisture.
Pull weeds carefully around your garlic and onion beds now, as they are storing energy for bulb development before winter.
Great Falls gardening questions
3Can I still start seeds for next spring indoors, or is it too late?
No new sowings are recommended right now as your last frost date averages May 12th; you must wait until soil thaws completely in April to sow cold-tender starts like Basil or Pepper outdoors.
How do I store the Garlic and Shallots harvested this week given our dry Montana summer?
Cure these bulbs by hanging them in a warm, dark, well-ventilated spot for two weeks until skins are papery before storing them in mesh bags away from the root cellar to prevent premature sprouting.
Will my Ornamental Sweet Potato Vine and Vinca survive the winter outdoors?
Absolutely not; these tropical perennials will die instantly when temperatures approach our Zone 4b minimum of -25°F, so dig up tubers if possible or cut vines to bring indoors as houseplants.
Other cities in zone 4b
3See the full zone 4b guide → · Plan your Great Falls garden in SproutGuide →