Zone 4b planting calendar
Cool climate with a roughly 4.5-month frost-free season.
Coldest temps-25 to -20°F
Avg. last spring frostMay 10
Avg. first fall frostSep 22
Open the interactive calendar for Zone 4b →
The growing season in Zone 4b
Zone 4b has a coldest-winter range of -25 to -20°F and an average frost-free growing season of roughly 135 days — from the last spring frost around May 10 to the first fall frost around Sep 22. That is a moderate season that comfortably suits most vegetables, with time for a spring and a fall planting of the cool-season crops.
The practical rhythm here is simple. Cool-season crops — peas, spinach, lettuce, radishes, and the brassicas — can go out around the last-frost date and again for a fall crop. Frost-tender crops like tomatoes, peppers, squash, and basil wait until after May 10, and the longer-season ones among them (melons, winter squash, full-size tomatoes) are the plants to watch against the 135-day window. Start those indoors on the schedule below so they have time to finish before fall frost returns.
What to plant in Zone 4b
Every crop below is timed to Zone 4b's frost dates. Follow a crop link for its full growing profile across all zones, or open the interactive calendar for the month-by-month view.
| Crop | When to plant |
|---|---|
| Tomato | Start seeds indoors Mar 22–Apr 5 Transplant outdoors May 17–May 24 |
| Pepper | Start seeds indoors Mar 8–Mar 22 Transplant outdoors May 24–May 31 |
| Lettuce | Direct sow outdoors Apr 12–May 10 Direct sow outdoors Jul 28–Aug 11 |
| Carrot | Direct sow outdoors Apr 19–May 24 Direct sow outdoors Jul 14–Jul 28 |
| Bush Bean | Direct sow outdoors May 10–Jun 7 |
| Cucumber | Start seeds indoors Apr 19–Apr 26 Transplant outdoors May 17–May 24 Direct sow outdoors May 17–May 31 |
| Zucchini | Direct sow outdoors May 10–May 31 |
| Spinach | Direct sow outdoors Mar 29–Apr 26 Direct sow outdoors Jul 28–Aug 18 |
| Kale | Start seeds indoors Mar 29–Apr 12 Transplant outdoors Apr 26–May 10 Direct sow outdoors Apr 26–May 24 Direct sow outdoors Jun 30–Jul 28 |
| Pea | Direct sow outdoors Mar 29–Apr 19 |
| Basil | Start seeds indoors Mar 29–Apr 12 Transplant outdoors May 17–May 31 |
| Cilantro | Direct sow outdoors Apr 19–May 17 Direct sow outdoors Jul 28–Aug 18 |
| Broccoli | Start seeds indoors Mar 22–Apr 5 Transplant outdoors Apr 26–May 10 Direct sow outdoors Jun 16–Jul 7 |
| Cabbage | Start seeds indoors Mar 15–Mar 29 Transplant outdoors Apr 26–May 10 |
| Cauliflower | Start seeds indoors Mar 22–Apr 5 Transplant outdoors Apr 26–May 10 |
| Brussels Sprouts | Start seeds indoors Mar 29–Apr 12 Transplant outdoors May 3–May 17 |
| Onion | Start seeds indoors Mar 1–Mar 15 Transplant outdoors Apr 12–Apr 26 |
| Garlic | Direct sow outdoors Aug 25–Sep 8 |
| Beet | Direct sow outdoors Apr 12–May 10 Direct sow outdoors Jul 14–Jul 28 |
| Radish | Direct sow outdoors Apr 12–May 24 Direct sow outdoors Jul 28–Aug 25 |
| Swiss Chard | Direct sow outdoors Apr 26–May 24 |
| Potato | Direct sow outdoors Apr 26–May 24 |
| Sweet Corn | Direct sow outdoors May 10–May 31 |
| Eggplant | Start seeds indoors Mar 15–Mar 29 Transplant outdoors May 24–May 31 |
| Pumpkin | Direct sow outdoors May 10–May 31 |
| Winter Squash | Direct sow outdoors May 10–May 31 |
| Arugula | Direct sow outdoors Apr 12–May 10 Direct sow outdoors Jul 28–Aug 25 |
| Leek | Start seeds indoors Mar 1–Mar 15 Transplant outdoors Apr 12–Apr 26 |
| Turnip | Direct sow outdoors Apr 12–May 10 Direct sow outdoors Jul 28–Aug 11 |
| Kohlrabi | Direct sow outdoors Apr 12–May 10 Direct sow outdoors Jul 28–Aug 11 |
| Okra | Start seeds indoors Apr 12–Apr 26 Direct sow outdoors May 17–May 31 |
| Celery | Start seeds indoors Mar 1–Mar 15 Transplant outdoors May 3–May 17 |
| Collard Greens | Start seeds indoors Mar 29–Apr 12 Transplant outdoors Apr 26–May 10 Direct sow outdoors Jun 30–Jul 28 |
| Mustard Greens | Direct sow outdoors Apr 12–May 10 Direct sow outdoors Jul 28–Aug 18 |
| Bok Choy | Direct sow outdoors Apr 19–May 10 Direct sow outdoors Jul 28–Aug 18 |
| Fennel | Direct sow outdoors Apr 26–May 24 Direct sow outdoors Jul 14–Jul 28 |
| Sweet Potato | Transplant outdoors May 24–Jun 7 |
| Parsnip | Direct sow outdoors Apr 26–May 24 |
| Asparagus | Transplant outdoors Apr 12–Apr 26 |
| Parsley | Start seeds indoors Mar 15–Mar 29 Transplant outdoors Apr 26–May 10 Direct sow outdoors Apr 26–May 24 |
| Dill | Direct sow outdoors Apr 26–May 24 Direct sow outdoors Jul 28–Aug 11 |
| Chives | Start seeds indoors Mar 15–Mar 29 Transplant outdoors Apr 26–May 10 |
| Thyme | Start seeds indoors Mar 15–Mar 29 Transplant outdoors May 10–May 24 |
| Oregano | Start seeds indoors Mar 15–Mar 29 Transplant outdoors May 10–May 24 |
| Sage | Start seeds indoors Mar 15–Mar 29 Transplant outdoors May 10–May 24 |
| Rosemary | Start seeds indoors Mar 1–Mar 15 Transplant outdoors May 24–Jun 7 |
| Mint | Transplant outdoors May 10–May 24 |
| Lavender | Start seeds indoors Mar 1–Mar 15 Transplant outdoors May 10–May 24 |
| Chamomile | Direct sow outdoors Apr 26–May 24 |
| Lemon Balm | Start seeds indoors Mar 15–Mar 29 Transplant outdoors May 10–May 24 |
| Tarragon | Transplant outdoors May 10–May 24 |
| Strawberry | Transplant outdoors Apr 12–Apr 26 |
| Watermelon | Start seeds indoors Apr 12–Apr 26 Transplant outdoors May 24–May 31 Direct sow outdoors May 17–May 31 |
| Cantaloupe | Start seeds indoors Apr 12–Apr 26 Transplant outdoors May 24–May 31 Direct sow outdoors May 17–May 31 |
| Ground Cherry | Start seeds indoors Mar 22–Apr 5 Transplant outdoors May 17–May 24 |
| Blueberry | Transplant outdoors Apr 12–Apr 26 |
| Raspberry | Transplant outdoors Apr 5–Apr 19 |
| Blackberry | Transplant outdoors Apr 5–Apr 19 |
| Rhubarb | Transplant outdoors Apr 5–Apr 19 |
| Currant | Transplant outdoors Mar 29–Apr 19 |
| Gooseberry | Transplant outdoors Mar 29–Apr 19 |
| Marigold | Start seeds indoors Mar 29–Apr 12 Transplant outdoors May 17–May 24 Direct sow outdoors May 10–May 24 |
| Zinnia | Start seeds indoors Apr 12–Apr 26 Transplant outdoors May 17–May 24 Direct sow outdoors May 10–May 24 |
| Sunflower | Direct sow outdoors May 10–May 31 |
| Cosmos | Direct sow outdoors May 10–May 24 |
| Nasturtium | Direct sow outdoors May 10–May 24 |
| Sweet Pea | Direct sow outdoors Mar 29–Apr 19 |
| Snapdragon | Start seeds indoors Mar 15–Mar 29 Transplant outdoors Apr 26–May 10 |
| Pansy | Start seeds indoors Mar 1–Mar 15 Transplant outdoors Apr 12–Apr 26 |
| Dahlia | Start seeds indoors Apr 12–Apr 26 Transplant outdoors May 17–May 24 |
| Calendula | Direct sow outdoors Apr 26–May 24 Direct sow outdoors Jul 28–Aug 11 |
| Poppy | Direct sow outdoors Mar 29–Apr 26 |
| Cornflower | Direct sow outdoors Apr 12–May 3 Direct sow outdoors Jul 28–Aug 11 |
| Aster | Start seeds indoors Mar 29–Apr 12 Transplant outdoors May 10–May 24 |
| Celosia | Start seeds indoors Mar 29–Apr 12 Transplant outdoors May 17–May 24 |
| Sweet Alyssum | Direct sow outdoors Apr 26–May 24 |
| Morning Glory | Direct sow outdoors May 10–May 24 |