Zone 4b Planting Calendar
In zone 4b, the median last spring frost falls around May 5 and the first fall frost around Oct 5, giving roughly 152 frost-free days. Average annual minimum temperature is -25°F to -20°F. Every date in the table below is calculated from those two frost dates.
Comparable areas: Bismarck, ND, Eau Claire, WI, Berlin, NH. Upper Midwest, northern New England and the northern Rockies. Wide spread within the zone: a Rocky Mountain 4b valley can be 40+ days shorter than a 4b site in central Wisconsin at the same latitude.
What to plant and when in zone 4b
Sorted by when you start each crop. Dates are calculated from a median last frost of May 5 and a first frost of Oct 5.
| Crop | Start indoors | Plant outside | Fall sowing | Harvest from |
|---|---|---|---|---|
| Celery | Feb 10 – Feb 24 | May 19 – Jun 1 | — | Aug 27 – Sep 26 |
| Leek | Feb 10 – Mar 10 | Apr 7 – Apr 20 | — | Jul 6 – Sep 4 |
| Onion | Feb 10 – Feb 24 | Apr 14 – Apr 27 | — | Jul 23 – Aug 12 |
| Rosemary | Feb 10 – Feb 24 | May 19 – Jun 1 | — | Aug 7 – Aug 27 |
| Kale | Feb 17 – Mar 10 | Apr 7 – Apr 20 | Jul 13 – Jul 26 | May 27 – Jun 28 |
| Broccoli | Feb 24 – Mar 17 | Apr 14 – Apr 27 | Jul 6 – Jul 19 | Jun 3 – Jul 13 |
| Cabbage | Feb 24 – Mar 17 | Apr 14 – Apr 27 | Jul 6 – Jul 19 | Jun 13 – Jul 23 |
| Pepper (sweet/bell) | Feb 24 – Mar 24 | May 26 – Jun 8 | — | Aug 4 – Aug 19 |
| Chives | Feb 24 – Mar 10 | May 5 – May 18 | — | Jul 24 – Aug 3 |
| Common Thyme | Feb 24 – Mar 10 | May 5 – May 18 | — | Jul 4 – Aug 3 |
| Greek Oregano | Feb 24 – Mar 10 | May 5 – May 18 | — | Jul 24 – Aug 3 |
| Cauliflower | Mar 3 – Mar 24 | Apr 21 – May 4 | Jul 6 – Jul 19 | Jun 10 – Jul 10 |
| Eggplant | Mar 10 – Mar 24 | May 19 – Jun 1 | — | Jul 13 – Aug 7 |
| Sweet Potato | Mar 10 – Mar 24 | May 26 – Jun 8 | — | Aug 24 – Sep 23 |
| Basil | Mar 10 – Mar 24 | May 12 – May 25 | — | Jul 18 – Aug 17 |
| Garden Sage | Mar 10 – Mar 24 | May 5 – May 18 | — | Jul 14 – Jul 24 |
| Parsley | Mar 10 – Mar 24 | May 5 – May 18 | Jul 27 – Aug 9 | Jul 14 – Jul 24 |
| Spearmint | Mar 10 – Mar 24 | May 5 – May 18 | — | Jul 4 – Aug 3 |
| Calendula / Pot Marigold | Mar 10 – Mar 24 | Apr 21 – May 4 | Aug 10 – Aug 23 | Jun 10 – Jun 20 |
| French Marigold | Mar 10 – Apr 7 | May 12 – May 25 | — | Jun 26 – Jul 11 |
| Sweet Alyssum | Mar 10 – Mar 24 | Apr 21 – May 4 | Aug 10 – Aug 23 | Jun 2 – Jun 16 |
| Tomato | Mar 17 – Mar 31 | May 12 – May 25 | — | Jul 6 – Aug 10 |
| Bok Choy | Mar 24 – Apr 7 | Apr 21 – May 4 | Aug 10 – Aug 23 | May 21 – Jun 20 |
| Collard Greens | Mar 24 – Apr 7 | Apr 21 – May 4 | Jul 13 – Jul 26 | Jun 20 – Jul 10 |
| Kohlrabi | Mar 24 – Apr 7 | Apr 14 – Apr 27 | Aug 3 – Aug 16 | Jun 10 – Jun 20 |
| Lettuce | Mar 24 – Apr 7 | Apr 14 – Apr 27 | Jul 27 – Aug 9 | Jun 10 – Jun 30 |
| Spinach | Mar 24 – Mar 31 | Apr 14 – Apr 27 | Aug 17 – Aug 30 | Jun 11 – Jun 22 |
| Swiss Chard | Mar 24 – Apr 7 | Apr 21 – May 4 | Sep 7 – Sep 20 | May 31 – Jun 15 |
| Pea | — | Mar 31 – Apr 13 | Aug 3 – Aug 16 | May 25 – Jun 14 |
| Rhubarb | — | Mar 31 – Apr 13 | — | Mar 30 |
| Watermelon | Mar 31 – Apr 21 | May 19 – Jun 1 | — | Jul 28 – Aug 22 |
| Arugula | — | Apr 7 – Apr 20 | Aug 24 – Sep 6 | May 7 – May 27 |
| Asparagus | — | Apr 7 – Apr 20 | — | Apr 6 |
| Cucumber | Apr 7 – Apr 21 | May 19 – Jun 1 | — | Jul 8 – Jul 28 |
| Pumpkin | Apr 7 – Apr 14 | May 19 – Jun 1 | — | Aug 12 – Sep 16 |
| Turnip | — | Apr 7 – Apr 20 | Aug 3 – Aug 16 | May 17 – Jun 21 |
| Nasturtium | Apr 7 – Apr 14 | May 12 – May 25 | — | Jul 6 – Jul 16 |
| Beet | — | Apr 14 – Apr 27 | Jul 27 – Aug 9 | Jun 3 – Jun 23 |
| Carrot | — | Apr 14 – Apr 27 | Jul 20 – Aug 2 | Jun 13 – Jul 3 |
| Potato | — | Apr 14 – Apr 27 | — | Jun 23 – Aug 12 |
| Radish | — | Apr 14 – Apr 27 | Aug 24 – Sep 6 | May 5 – May 29 |
| Sunflower | Apr 14 – Apr 21 | May 12 – May 25 | — | Jul 21 – Aug 20 |
| Parsnip | — | Apr 21 – May 4 | — | Aug 9 – Aug 29 |
| Winter Squash (Butternut) | Apr 21 – Apr 28 | May 19 – Jun 1 | — | Aug 7 – Aug 27 |
| Cantaloupe (Muskmelon) | Apr 21 – Apr 28 | May 19 – Jun 1 | — | Jul 26 – Aug 12 |
| Strawberry | — | Apr 21 – May 4 | — | May 19 – May 21 |
| Dill | — | Apr 28 – May 11 | Jul 27 – Aug 9 | Jun 7 – Jun 22 |
| Bush bean | — | May 5 – May 18 | Jul 27 – Aug 9 | Jun 24 – Jul 4 |
| Pole bean | — | May 5 – May 18 | — | Jul 2 – Jul 7 |
| Sweet corn | — | May 5 – May 18 | — | Jul 4 – Aug 13 |
| Borage | — | May 5 – May 18 | — | Jun 24 – Jul 4 |
| Cilantro / Coriander | — | May 5 – May 18 | Aug 10 – Aug 23 | Jun 19 – Jul 14 |
| Summer squash / zucchini | — | May 12 – May 25 | — | Jun 16 – Jul 6 |
| Okra | — | May 19 – Jun 1 | — | Jul 18 – Jul 28 |
| Brussels Sprouts | — | Jul 14 – Jul 27 | Jun 29 – Jul 12 | Oct 7 – Nov 1 |
| Garlic | — | — | Oct 5 – Oct 18 | — |
Print this page for a calendar you can pin up in the shed.
Get reminded at the right week
FreePlanting dates are only useful if you remember them. Tell us your zone and we'll email you when it's time to start seeds indoors, when your last frost is close, and when the autumn sowing window opens — dated for your climate, not someone else's.
Seasonal sends only — roughly one a month, more in spring. No selling your address, unsubscribe in one click. Don't know your zone?
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 4b 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 →
Other zones
Not sure which zone you're in? Look it up by ZIP code →