Zone 3b Planting Calendar
In zone 3b, the median last spring frost falls around May 22 and the first fall frost around Sep 20, giving roughly 120 frost-free days. Average annual minimum temperature is -35°F to -30°F. Every date in the table below is calculated from those two frost dates.
Comparable areas: Bemidji, MN, Devils Lake, ND, Houlton, ME. Northern Plains and northern Great Lakes. Frost-free season is short and highly variable year to year; late-May and early-September frosts are routine. Cold-air-drainage hollows within this zone lose 2-3 weeks off both ends.
What to plant and when in zone 3b
Sorted by when you start each crop. Dates are calculated from a median last frost of May 22 and a first frost of Sep 20.
| Crop | Start indoors | Plant outside | Fall sowing | Harvest from |
|---|---|---|---|---|
| Celery | Feb 27 – Mar 13 | Jun 5 – Jun 18 | — | Sep 13 – Oct 13 |
| Leek | Feb 27 – Mar 27 | Apr 24 – May 7 | — | Jul 23 – Sep 21 |
| Onion | Feb 27 – Mar 13 | May 1 – May 14 | — | Aug 9 – Aug 29 |
| Rosemary | Feb 27 – Mar 13 | Jun 5 – Jun 18 | — | Aug 24 – Sep 13 |
| Kale | Mar 6 – Mar 27 | Apr 24 – May 7 | Jun 28 – Jul 11 | Jun 13 – Jul 15 |
| Broccoli | Mar 13 – Apr 3 | May 1 – May 14 | Jun 21 – Jul 4 | Jun 20 – Jul 30 |
| Cabbage | Mar 13 – Apr 3 | May 1 – May 14 | Jun 21 – Jul 4 | Jun 30 – Aug 9 |
| Pepper (sweet/bell) | Mar 13 – Apr 10 | Jun 12 – Jun 25 | — | Aug 21 – Sep 5 |
| Chives | Mar 13 – Mar 27 | May 22 – Jun 4 | — | Aug 10 – Aug 20 |
| Common Thyme | Mar 13 – Mar 27 | May 22 – Jun 4 | — | Jul 21 – Aug 20 |
| Greek Oregano | Mar 13 – Mar 27 | May 22 – Jun 4 | — | Aug 10 – Aug 20 |
| Cauliflower | Mar 20 – Apr 10 | May 8 – May 21 | Jun 21 – Jul 4 | Jun 27 – Jul 27 |
| Eggplant | Mar 27 – Apr 10 | Jun 5 – Jun 18 | — | Jul 30 – Aug 24 |
| Sweet Potato | Mar 27 – Apr 10 | Jun 12 – Jun 25 | — | Sep 10 – Oct 10 |
| Basil | Mar 27 – Apr 10 | May 29 – Jun 11 | — | Aug 4 – Sep 3 |
| Garden Sage | Mar 27 – Apr 10 | May 22 – Jun 4 | — | Jul 31 – Aug 10 |
| Parsley | Mar 27 – Apr 10 | May 22 – Jun 4 | Jul 12 – Jul 25 | Jul 31 – Aug 10 |
| Spearmint | Mar 27 – Apr 10 | May 22 – Jun 4 | — | Jul 21 – Aug 20 |
| Calendula / Pot Marigold | Mar 27 – Apr 10 | May 8 – May 21 | Jul 26 – Aug 8 | Jun 27 – Jul 7 |
| French Marigold | Mar 27 – Apr 24 | May 29 – Jun 11 | — | Jul 13 – Jul 28 |
| Sweet Alyssum | Mar 27 – Apr 10 | May 8 – May 21 | Jul 26 – Aug 8 | Jun 19 – Jul 3 |
| Tomato | Apr 3 – Apr 17 | May 29 – Jun 11 | — | Jul 23 – Aug 27 |
| Bok Choy | Apr 10 – Apr 24 | May 8 – May 21 | Jul 26 – Aug 8 | Jun 7 – Jul 7 |
| Collard Greens | Apr 10 – Apr 24 | May 8 – May 21 | Jun 28 – Jul 11 | Jul 7 – Jul 27 |
| Kohlrabi | Apr 10 – Apr 24 | May 1 – May 14 | Jul 19 – Aug 1 | Jun 27 – Jul 7 |
| Lettuce | Apr 10 – Apr 24 | May 1 – May 14 | Jul 12 – Jul 25 | Jun 27 – Jul 17 |
| Spinach | Apr 10 – Apr 17 | May 1 – May 14 | Aug 2 – Aug 15 | Jun 28 – Jul 9 |
| Swiss Chard | Apr 10 – Apr 24 | May 8 – May 21 | Aug 23 – Sep 5 | Jun 17 – Jul 2 |
| Pea | — | Apr 17 – Apr 30 | Jul 19 – Aug 1 | Jun 11 – Jul 1 |
| Rhubarb | — | Apr 17 – Apr 30 | — | Apr 16 |
| Watermelon | Apr 17 – May 8 | Jun 5 – Jun 18 | — | Aug 14 – Sep 8 |
| Arugula | — | Apr 24 – May 7 | Aug 9 – Aug 22 | May 24 – Jun 13 |
| Asparagus | — | Apr 24 – May 7 | — | Apr 23 |
| Cucumber | Apr 24 – May 8 | Jun 5 – Jun 18 | — | Jul 25 – Aug 14 |
| Pumpkin | Apr 24 – May 1 | Jun 5 – Jun 18 | — | Aug 29 – Oct 3 |
| Turnip | — | Apr 24 – May 7 | Jul 19 – Aug 1 | Jun 3 – Jul 8 |
| Nasturtium | Apr 24 – May 1 | May 29 – Jun 11 | — | Jul 23 – Aug 2 |
| Beet | — | May 1 – May 14 | Jul 12 – Jul 25 | Jun 20 – Jul 10 |
| Carrot | — | May 1 – May 14 | Jul 5 – Jul 18 | Jun 30 – Jul 20 |
| Potato | — | May 1 – May 14 | — | Jul 10 – Aug 29 |
| Radish | — | May 1 – May 14 | Aug 9 – Aug 22 | May 22 – Jun 15 |
| Sunflower | May 1 – May 8 | May 29 – Jun 11 | — | Aug 7 – Sep 6 |
| Parsnip | — | May 8 – May 21 | — | Aug 26 – Sep 15 |
| Winter Squash (Butternut) | May 8 – May 15 | Jun 5 – Jun 18 | — | Aug 24 – Sep 13 |
| Cantaloupe (Muskmelon) | May 8 – May 15 | Jun 5 – Jun 18 | — | Aug 12 – Aug 29 |
| Strawberry | — | May 8 – May 21 | — | Jun 5 – Jun 7 |
| Dill | — | May 15 – May 28 | Jul 12 – Jul 25 | Jun 24 – Jul 9 |
| Bush bean | — | May 22 – Jun 4 | Jul 12 – Jul 25 | Jul 11 – Jul 21 |
| Pole bean | — | May 22 – Jun 4 | — | Jul 19 – Jul 24 |
| Sweet corn | — | May 22 – Jun 4 | — | Jul 21 – Aug 30 |
| Borage | — | May 22 – Jun 4 | — | Jul 11 – Jul 21 |
| Cilantro / Coriander | — | May 22 – Jun 4 | Jul 26 – Aug 8 | Jul 6 – Jul 31 |
| Summer squash / zucchini | — | May 29 – Jun 11 | — | Jul 3 – Jul 23 |
| Okra | — | Jun 5 – Jun 18 | — | Aug 4 – Aug 14 |
| Brussels Sprouts | — | Jul 31 – Aug 13 | Jun 14 – Jun 27 | Oct 24 – Nov 18 |
| Garlic | — | — | Sep 20 – Oct 3 | — |
Print this page for a calendar you can pin up in the shed.
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One zone is not one climate. USDA hardiness zones are drawn from average winter minimum temperature and nothing else, so they do not determine frost dates. Two gardens in zone 3b can differ by two or three weeks depending on elevation, distance from water, and local topography. Treat this page as a starting schedule and adjust it to what your own garden has actually done. How these dates were derived →
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