What to plant this week in Duluth, MN
With temperatures hovering near the -25°F winter low and your last frost averaging May 12, Duluth gardeners are currently in a late-season harvest window rather than a planting phase. This week marks the final sprint for warm-weather crops like Beefsteak Tomatoes and Zucchini before the first hard freeze arrives on October 1.
The next 7 days
Duluth, MNGrowing in Duluth right now
- Harvest mature Winter Squash, Pumpkins, and Rutabagas immediately to store through Duluth's long, damp fall; leave vines attached if possible to slow rot in humid conditions.
- Protect late-season Brassicas like Brussels Sprouts and Leeks with heavy row covers or fleece as nightly lows drop rapidly after mid-October.
- Clear spent Cosmos and Marigolds from beds now that they are done flowering to prevent seed heads from shattering in the high winds common on Lake Superior shores.
- Avoid sowing any cool-season seeds this week; focus entirely on pulling, curing, and covering remaining plants for winter storage or frost protection.
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
- Watch for late-season aphid colonies on Brassicas as they seek warmth during cold snaps before freezing them out naturally.
- Monitor for squash vine borers in Zucchini and Summer Squash one last time; check stems for frass and inject insecticide if infestation is light, though harvest often outweighs treatment effort at this stage.
- Beware of slugs and snails feasting on Tender herbs like Basil and Shiso during warm, wet fall nights before the ground freezes.
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.
Duluth gardening questions
3Can I still plant Garlic in Duluth right now?
Yes, late September through early October is prime time for planting hardneck garlic varieties suited to Zone 4b soil. Wait until the ground can be worked but leave it unmulched until after the initial freeze helps seal the bulbs.
When should I stop watering my tomatoes and peppers?
Stop overhead watering one week before your first expected frost, around September 24, to prevent blossom-end rot and reduce fungal pressure in our humid climate. Continue deep soil moisture checks but avoid wetting the foliage entirely.
How do I prepare Zucchini for winter storage given Duluth's humidity?
Harvest zucchini when they are small to medium-sized rather than letting them grow large, as smaller fruit stores much better in cool root cellars. Cure them at room temperature for a few days before placing them in breathable containers away from direct light.
Other cities in zone 4b
3See the full zone 4b guide → · Plan your Duluth garden in SproutGuide →