What to plant this week in Duluth, MN
With average last frost historically around May 12, Duluth gardeners are finally seeing the first major harvests of summer crops like Zucchini and Sweet Corn. While soil temperatures in our clay-heavy river valleys have warmed up enough for transplants, be wary of sudden late spring freezes that can still occur before mid-May.
The next 7 days
Duluth, MNGrowing in Duluth right now
- Our local red clay soils retain moisture well during our dry spells but become heavy and slow to warm; till deeply now to break up the crust if you haven't already.
- Take advantage of this week's harvest window for fast-maturing items like Bush Beans, Swiss Chard, and Napa Cabbage before summer heat peaks.
- Protect your early Pansies and Vinca from our frequent wind chill events by using temporary row covers or moving them to sheltered spots near buildings.
- Since frost dates often drift late in this northern region, delay transplanting sensitive peppers and tomatoes until after May 15 to avoid shock.
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
- Watch for early cabbage loopers on your newly planted Cabbage and Collard Greens as temperatures rise above 60°F.
- Spider mites can appear quickly in our dry, windy conditions; inspect the undersides of your Yellow Summer Squash leaves daily.
- Slugs remain active during the cool, damp nights typical of Duluth spring weather; check seedlings of Tomato and Potato vines each morning.
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.
Duluth gardening questions
3Is it safe to plant my Zucchini seeds directly in the ground this week?
Not yet; our local clay freezes late into April and is too cold for warm-weather crops like Zucchini right now. Wait until the soil consistently reaches 60°F, usually a few weeks after May 12.
When should I transplant my Tomato plants to avoid frost damage?
Aim for mid-May or later, giving you two full weeks of buffer time past our average last frost date of May 12. Hardening them off gradually is critical before moving them into our brisk spring winds.
Can I start harvesting my Bachelor's Button (Cornflower) now?
Yes, these annuals are ready to cut for bouquets or fresh arrangements this week as they bloom in response to the warming days. Pinch back any spent flowers to encourage a second flush of blooms later in summer.
Other cities in zone 4b
3See the full zone 4b guide → · Plan your Duluth garden in SproutGuide →