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Zone 4B — September

What to Plant in September in Zone 4B

September in Zone 4B: 0 crops to start indoors, 0 to plant or direct sow outside, and 140 entering harvest window. Last frost averages May 11. Reference city: St. Cloud, MN.
Updated August 12, 2026 · Frost data from NOAA 1991-2020 Climate Normals
0 Start Indoors
0 Plant Outside
140 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: February — 2 varieties, including King Richard Leek, Viola and pansy edible flowers.

Plant Outside in September

Nothing to plant or sow outside in September for Zone 4B.
Next window: October — 11 varieties, including Asian Tempest Garlic, Chengdu Garlic, Chesnok Red Garlic.

Harvest in September

Plant Type Planted / Sown Harvest Window
Atlantic Giant Pumpkin squash May 18 Sep 5
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
Carolina Cross Watermelon melon May 25 Sep 2
Cinderella Pumpkin squash May 18 Sep 10
Goldrush Potato root vegetable May 18 Sep 6 – Sep 15
Grano Red Onions allium May 11 Sep 8
Grano White Onions allium May 11 Sep 8
Green Hubbard Winter Squash squash May 18 Sep 5
Harris Model Parsnips root vegetable May 18 Sep 10 – Sep 15
Indian Spring Mix Hollyhock Flowers flower May 11 Sep 8 – Sep 23 (before frost)
Kennebec Potato root vegetable May 18 Sep 5 – Sep 30
Long Island Cheese Winter Squash squash May 18 Sep 3
Luffa gourds vegetable May 25 Sep 2 – Sep 22
Mammoth Sandwich Island Salsify root vegetable May 18 Sep 15
Pacific Giant Pumpkin squash May 18 Sep 10 – Sep 20
Southport Red Globe Onions allium May 11 Sep 8
Southport White Globe Onions allium May 11 Sep 8
Summer Carnival Mix Hollyhock Flowers flower May 11 Sep 8 – Sep 23 (before frost)
Waltham Butternut Squash squash May 25 Sep 2 – Sep 22
Adirondack Blue Potato (fall planting) root vegetable Jul 5 Sep 30
All Season Cabbage (fall planting) brassica Jul 5 Sep 23
All Year Round Cauliflower (fall planting) brassica Jul 5 Sep 8
All Year Round Lettuce (fall planting) lettuce Jul 5 Sep 16
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) allium Jul 5 Sep 23
Blonde de Paris Lettuce (fall planting) lettuce Jul 5 Sep 3
Blue Curled Scotch Kale (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 23
Broadleaf Classic Endive (fall planting) lettuce Jul 5 Sep 3
Broccolini (fall planting) brassica Jul 5 Sep 3
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 Swiss Chard (fall planting) lettuce Jul 5 Sep 3
Cascadia Sugar Snap Pea (fall planting) legume Jul 5 Sep 3
Chantenay Carrots (fall planting) root vegetable Jul 5 Sep 13
Charleston Wakefield Cabbage (fall planting) brassica Jul 5 Sep 13
Chinese Broccoli (Gai Lan) (fall planting) brassica Jul 5 Sep 13
Chinese Forget-Me-Not Flowers (fall planting) flower Jul 5 Sep 28
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) allium Jul 5 Sep 3
Crisphead Lettuce (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 Lettuce (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
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 Bunching Onions (fall planting) allium Jul 5 Sep 8
Evergreen Parsley (fall planting) herb Jul 5 Sep 28
Georgia Southern Collard Greens (fall planting) lettuce Jul 5 Sep 28
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 Swiss Chard (fall planting) lettuce Jul 5 Sep 3
Iceberg Lettuce (fall planting) lettuce Jul 5 Sep 18
Igloo Cauliflower (fall planting) brassica Jul 5 Sep 13
Kagraner Sommer Lettuce (fall planting) lettuce Jul 5 Sep 1
King Richard Leek (fall planting) allium Jul 5 Sep 18
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 3
Little Marvel Pea (fall planting) legume Jul 5 Sep 6
Lollo Bionda Lettuce (fall planting) lettuce Jul 5 Sep 3
Love-in-a-Mist Flowers (fall planting) flower Jul 5 Sep 13
Lunar White Carrots (fall planting) root vegetable Jul 5 Sep 3
Magenta Sunset Swiss Chard (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 18
Marvel of Four Seasons Lettuce (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 Collard (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
Napa Cabbage (fall planting) brassica Jul 5 Sep 13
Nutri-Red Carrots (fall planting) root vegetable Jul 5 Sep 13
Oregon Giant Snow Pea (fall planting) legume Jul 5 Sep 3
Oregon Sugar Pod Snow Pea (fall planting) legume Jul 5 Sep 11
Orion Florence Fennel (fall planting) vegetable Jul 5 Sep 23
Par-Cel Cutting Celery (fall planting) vegetable Jul 5 Sep 28
Paris Market Carrots (fall planting) root vegetable Jul 5 Sep 8
Phacelia cover crop and bee forage (fall planting) cover crop Jul 5 Sep 3
Premier Kale (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
Queen Anne's Lace Flowers (fall planting) flower Jul 5 Sep 18
Radicchio (fall planting) lettuce Jul 5 Sep 28
Rainbow Mix Swiss Chard (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 Lettuce (fall planting) lettuce Jul 5 Sep 13
Romaine Lettuce (fall planting) lettuce Jul 5 Sep 18
Royal Carpet Alyssum Flowers (fall planting) flower Jul 5 Sep 3
Ruby Red Swiss Chard (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 Lettuce (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 Lettuce (fall planting) lettuce Jul 5 Sep 13
Très Fine Maraîchère Frisée (fall planting) lettuce Jul 5 Sep 3
Tuscany Black Kale (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
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) allium Jul 5 Sep 3
Winter Density Lettuce (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
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