Skip to main content
Zone 4B — September

What to Plant in September in Zone 4B

September in Zone 4B: 0 crops to start indoors, 1 to plant or direct sow outside, and 134 entering harvest window. Last frost averages May 11. Reference city: Duluth, MN.
Updated August 12, 2026 · Frost data from NOAA 1991-2020 Climate Normals
0 Start Indoors
1 Plant Outside
134 Harvest
Frost risk: Cleared

Frost season has cleared in Zone 4B. The last spring frost typically passed by May 11, and the very latest 10% chance closed by May 25. Tender crops are safe to plant out.

See full Zone 4B frost outlook →

Start Indoors in September

Nothing to start seeds indoors in September for Zone 4B.
Next window: November — 1 variety, including Garlic.

Plant Outside in September

Plant Type Action Target Date Harvest Window
Softneck Garlic root vegetable Plant Out Sep 2 Apr 30, 2027 – May 30, 2027

Harvest in September

Plant Type Planted / Sown Harvest Window
Atlantic Giant Pumpkin squash May 18 Sep 15
Big Max Pumpkin squash May 18 Sep 10 – Sep 15
Birds Eye Hot Peppers pepper May 25 Sep 2 – Sep 12
Bloody Butcher Corn vegetable May 25 Sep 2 – Sep 12
Butternut Squash squash May 25 Sep 2 – Sep 22
Cinderella Pumpkin squash May 18 Sep 5
Evergreen Bunching Onions root vegetable May 11 Sep 8
Grano Red Onions root vegetable May 11 Sep 8
Grano White Onions root vegetable May 11 Sep 8
Green Hubbard Winter Squash squash May 18 Sep 5
Indian Spring Mix Hollyhock Flowers flower May 11 Sep 8 – Sep 23 (before frost)
Luffa gourds vegetable May 25 Sep 2 – Sep 22
Pacific Giant Pumpkin squash May 18 Sep 10 – Sep 20
Southport Red Globe Onions root vegetable May 11 Sep 8
Southport White Globe Onions root vegetable May 11 Sep 8
Summer Carnival Mix Hollyhock Flowers flower May 11 Sep 8 – Sep 23 (before frost)
Alaska Early Pea (fall planting) legume Jul 5 Sep 3
All Season Cabbage (fall planting) brassica Jul 5 Sep 23
All Year Round (fall planting) lettuce Jul 5 Sep 16
All Year Round Cauliflower (fall planting) brassica Jul 5 Sep 8
Amarillo Yellow Carrots (fall planting) root vegetable Jul 5 Sep 18
Autumn King Carrots (fall planting) root vegetable Jul 5 Sep 23
Bachelor's button edible flowers (fall planting) flower Jul 5 Sep 23
Barletta, Pearly White Onions (fall planting) root vegetable Jul 5 Sep 23
Blonde de Paris (fall planting) lettuce Jul 5 Sep 3
Blue Curled Scotch (fall planting) lettuce Jul 5 Sep 3
Bok Choy (fall planting) lettuce Jul 5 Sep 3
Boltardy Beets (fall planting) root vegetable Jul 5 Sep 3
Bouquet Dill (fall planting) herb Jul 5 Sep 8
Broad Windsor Fava Bean (fall planting) legume Jul 5 Sep 28
Broadleaf Classic (fall planting) lettuce Jul 5 Sep 3
Broccolini (fall planting) brassica Jul 5 Sep 13
Butterhead Lettuce (fall planting) lettuce Jul 5 Sep 8
Calabrese Broccoli (fall planting) brassica Jul 5 Sep 8
Calendula (fall planting) flower Jul 5 Sep 3
California Bluebell (fall planting) flower Jul 5 Sep 8
Canary Yellow (fall planting) lettuce Jul 5 Sep 3
Cascadia Sugar Snap Pea (fall planting) legume Jul 5 Sep 10
Chantenay Carrots (fall planting) root vegetable Jul 5 Sep 13
Charleston Wakefield Cabbage (fall planting) brassica Jul 5 Sep 18
Chinese Forget-Me-Not Flowers (fall planting) flower Jul 5 Sep 28
Chioggia Beet (fall planting) root vegetable Jul 5 Sep 8
Copenhagen Cabbage (fall planting) brassica Jul 5 Sep 8
Cosmic Purple Carrot (fall planting) root vegetable Jul 5 Sep 18
Crimson Forest Bunching Onions (fall planting) root vegetable Jul 5 Sep 3
Crisphead (fall planting) lettuce Jul 5 Sep 18
Crosby's Egyptian Beets (fall planting) root vegetable Jul 5 Sep 3
Curly Kale (fall planting) lettuce Jul 5 Sep 8
Curly Parsley (fall planting) herb Jul 5 Sep 23
Cylindra Beets (fall planting) root vegetable Jul 5 Sep 3
Danvers Carrot (fall planting) root vegetable Jul 5 Sep 23
Dark Green Romaine (fall planting) lettuce Jul 5 Sep 13
Delicatesse Blue Kohlrabi (fall planting) brassica Jul 5 Sep 3
Delicatesse White Kohlrabi (fall planting) brassica Jul 5 Sep 3
Detroit Dark Red Beet (fall planting) root vegetable Jul 5 Sep 3
Di Cicco Broccoli (fall planting) brassica Jul 5 Sep 8
Early Jersey Wakefield Cabbage (fall planting) brassica Jul 5 Sep 18
Early Purple Broccoli (fall planting) brassica Jul 5 Sep 8
Endive / Escarole (fall planting) lettuce Jul 5 Sep 8
Evergreen Parsley (fall planting) herb Jul 5 Sep 28
Fairy Dwarf Mix Candytuft Flowers (fall planting) flower Jul 5 Sep 3
Georgia Southern Collard Greens (fall planting) lettuce Jul 5 Sep 23
German Chamomile (fall planting) herb Jul 5 Sep 8
Globe Gilia Flowers (fall planting) flower Jul 5 Sep 23
Golden Acre Cabbage (fall planting) brassica Jul 5 Sep 8
Golden Beet (fall planting) root vegetable Jul 5 Sep 8
Golden Detroit Beets (fall planting) root vegetable Jul 5 Sep 3
Green Arrow Pea (fall planting) legume Jul 5 Sep 13
Heritage Rainbow Blend Carrots (fall planting) root vegetable Jul 5 Sep 18
Hot Pink (fall planting) lettuce Jul 5 Sep 3
Iceberg (fall planting) lettuce Jul 5 Sep 18
Igloo Cauliflower (fall planting) brassica Jul 5 Sep 13
Kagraner Sommer (fall planting) lettuce Jul 5 Sep 1
Kuroda Carrots (fall planting) root vegetable Jul 5 Sep 13
Lacinato Kale (fall planting) lettuce Jul 5 Sep 8
Lacy Phacelia Flowers (fall planting) flower Jul 5 Sep 18
Little Marvel Pea (fall planting) legume Jul 5 Sep 6
Lollo Bionda (fall planting) lettuce Jul 5 Sep 3
Love-in-a-Mist Flowers (fall planting) flower Jul 5 Sep 28
Lunar White Carrots (fall planting) root vegetable Jul 5 Sep 23
Magenta Sunset (fall planting) lettuce Jul 5 Sep 3
Mammoth Dill (fall planting) herb Jul 5 Sep 8
Mammoth Melting Sugar Snow Pea (fall planting) legume Jul 5 Sep 17
Marvel of Four Seasons (fall planting) lettuce Jul 5 Sep 3
Medium Red Clover Cover Crop (fall planting) cover crop Jul 5 Sep 18
Michihili Cabbage (fall planting) brassica Jul 5 Sep 13
Morris Heading (fall planting) lettuce Jul 5 Sep 23
Mâche (Corn Salad) (fall planting) lettuce Jul 5 Sep 27
Nantes Carrot (fall planting) root vegetable Jul 8 Sep 21
New Zealand Spinach (fall planting) lettuce Jul 5 Sep 3
Nutri-Red Carrots (fall planting) root vegetable Jul 5 Sep 18
Oregon Giant Snow Pea (fall planting) legume Jul 5 Sep 17
Oregon Sugar Pod Snow Pea (fall planting) legume Jul 5 Sep 11
Phacelia cover crop and bee forage (fall planting) cover crop Jul 5 Sep 3
Premier (fall planting) lettuce Jul 5 Sep 3
Progress No. 9 Shelling Pea (fall planting) legume Jul 5 Sep 5
Purple Carrots (fall planting) root vegetable Jul 5 Sep 18
Purple Haze Carrots (fall planting) root vegetable Jul 5 Sep 16
Radicchio (fall planting) lettuce Jul 5 Sep 28
Rainbow Mix (fall planting) lettuce Jul 5 Sep 3
Rapeseed Cover Crop (fall planting) cover crop Jul 5 Sep 13
Rapini Broccoli Raab (fall planting) brassica Jul 5 Sep 8
Red Acre Cabbage (fall planting) brassica Jul 5 Sep 23
Red Romaine (fall planting) lettuce Jul 5 Sep 13
Red Russian Kale (fall planting) lettuce Jul 5 Sep 3
Romaine Lettuce (fall planting) lettuce Jul 5 Sep 18
Royal Carpet Alyssum Flowers (fall planting) flower Jul 5 Sep 3
Ruby Red (fall planting) lettuce Jul 5 Sep 3
Scarlet Flax Flowers (fall planting) flower Jul 5 Sep 13
Shelling Pea (fall planting) legume Jul 5 Sep 13
Snow Crown Cauliflower (fall planting) brassica Jul 5 Sep 3
Snow Pea (fall planting) legume Jul 5 Sep 13
Snow White Carrots (fall planting) root vegetable Jul 5 Sep 18
Snowball Self-Blanche Cauliflower (fall planting) brassica Jul 5 Sep 8
Solar Yellow Carrots (fall planting) root vegetable Jul 5 Sep 18
St. Valery Carrots (fall planting) root vegetable Jul 5 Sep 13
Sugar Snap Pea (fall planting) legume Jul 22 Sep 30
Summer Bibb (fall planting) lettuce Jul 5 Sep 3
Swiss Chard (fall planting) lettuce Jul 5 Sep 3
Tendersweet Carrots (fall planting) root vegetable Jul 5 Sep 13
Tom Thumb (fall planting) lettuce Jul 5 Sep 13
Turnip (fall planting) root vegetable Jul 5 Sep 3
Tuscany Black (fall planting) lettuce Jul 5 Sep 18
Vates Collard (fall planting) lettuce Jul 5 Sep 18
Vienna Purple Kohlrabi (fall planting) brassica Jul 5 Sep 8
Vienna White Kohlrabi (fall planting) brassica Jul 5 Sep 8
Vietnamese Coriander (fall planting) herb Jul 5 Sep 3
Viola and pansy edible flowers (fall planting) flower Jul 5 Sep 13
Violetta Purple Cauliflower (fall planting) brassica Jul 5 Sep 8
Wando Pea (fall planting) legume Jul 5 Sep 11
Watermelon Radishes (fall planting) root vegetable Jul 5 Sep 8
White Detroit Beets (fall planting) root vegetable Jul 5 Sep 3
White Lisbon Bunching Onions (fall planting) root vegetable Jul 5 Sep 8
Winter Density (fall planting) lettuce Jul 5 Sep 3

Key Tasks for September in Zone 4B

  1. 1 Check soil moisture before watering — stick a finger 2 inches into the soil. Water only when the soil is dry at that depth. Consistent moisture is more important than frequency.
Back to full Zone 4B planting calendar
August September in Zone 4B October

Get a Personalized September Calendar

SoilStack builds your exact planting schedule from your ZIP code — day-by-day tasks, weather prompts, and harvest tracking included.

Start Your Free Garden Calendar