What to plant this week in International Falls, MN
In International Falls, the week of September 20 marks your absolute final deadline for harvesting cool-season crops before the hard freeze hits. With minimum temperatures plummeting to -35°F and frost expected tonight, you must bring in all remaining lettuce, kale, and tomatoes immediately to save this season's yield.
The next 7 days
International Falls, MNGrowing in International Falls right now
- The ground here freezes rapidly once air temps drop, so do not wait for rain before harvesting root crops like carrots and turnips; they are too brittle if left in frozen soil.
- Your short growing window means late-season transplants like Zinnia or Cosmos will likely finish blooming but won't survive the night; prioritize cutting these flowers for bouquets instead of expecting winter growth.
- Ice storms and heavy lake-effect snows often begin this time of year, so clear drainage paths around your beds to prevent root rot from standing water before the freeze seals the ground.
- Protect your overwintering garlic and shallots by covering them with a thick layer of straw or pine boughs immediately after harvesting other crops to insulate against sub-zero winds.
Sow this week
No direct sowing windows open this week.
Transplant this week
Nothing is due to go out this week.
Harvest soon
38 crops- Bachelor's Button (Cornflower)
- Beet
- Borage
- Bush Bean
- Cabbage
- Calendula
- Carrot
- Cauliflower
- Cherry Tomato
- Chervil
- Cleome (Spider Flower)
- Collard Greens
- Cosmos
- Dill
- Fava (Broad) Bean
- French Marigold
- Garlic
- German Chamomile
- Kale
- Lettuce
- Napa Cabbage
- Onion
- Pansy
- Parsley
- Pole Bean
- Potato
- Scallion (Bunching Onion)
- Scarlet Runner Bean
- Shallot
- Snapdragon
- Sweet Alyssum
- Swiss Chard
- Tomato
- Turnip
- Vinca (Madagascar Periwinkle)
- Yellow Summer Squash
- Zinnia
- Zucchini
Seasonal tips
- Continue succession sowing bush beans and pole beans every two weeks to extend your harvest through summer.
- Mulch around young tomatoes and peppers to retain moisture as soil temperatures stabilize after the frost-free date.
- Pinch back the tops of Swiss chard and kale to encourage bushier growth before autumn frosts arrive.
Pest & disease watch
- Aphid colonies on late cabbage and kale will explode as temperatures drop, so spray with neem oil or strong water jets before plants bolt or freeze.
- Frost damage makes stressed lettuce and Swiss chard highly susceptible to rotting in the soil, so prioritize harvesting any wilted leaves for compost immediately.
- Watch for slugs on low-growing collards and mustard greens during damp nights, as they may still be active just before the ground freezes solid.
Watering this week
Provide deep watering two to three times per week, ensuring consistent moisture for seedlings like dill and chervil.
Harvest zucchini and yellow summer squash when they are small to prevent the plant from going into a dormant phase.
International Falls gardening questions
3Can I transplant any new flowers or vegetables next week in International Falls?
No, with an average last frost date of May 15 and first frost on September 20, the window for planting is officially closed. Any attempt to put seedlings like tomatoes or peppers into the ground now will result in immediate death from freezing temperatures.
How long can I leave harvested potatoes or onions outside before they freeze?
You have only a few days; once soil temps approach 28°F, potato skins and onion bulbs become brittle and prone to cracking. Harvest these root crops into dry conditions immediately and cure them indoors away from direct light.
Should I continue watering my garden this week before the freeze?
Water only if there is no rain forecast, as wet soil freezes faster than dry earth and can heave up sensitive roots like carrots. Let the moisture in the ground drop to near zero by September 20 so the soil structure remains intact under ice.
Other cities in zone 3b
4See the full zone 3b guide → · Plan your International Falls garden in SproutGuide →