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Zone 4b planting calendar and frost dates
In USDA hardiness zone 4b, the average last spring frost is May 13 and the average first fall frost is Sep 29, leaving about 139 frost-free days. To be 90% sure of no later frost, wait until about May 27 to plant tender crops. These are medians of 55 NOAA weather stations in zone 4b; their last-frost dates range from Apr 30 to Jun 15.
What to plant each month in zone 4b
February
Lavender (start indoors), Begonias (start indoors)
March
Tomatoes (start indoors), Bell peppers (start indoors), Kale (start indoors), Broccoli (start indoors), Cauliflower (start indoors), Cabbage (start indoors), Brussels sprouts (start indoors), Onions (start indoors), Basil (start indoors), Sage (start indoors), Coleus (start indoors), Marigolds (start indoors), Foxglove (start indoors), Coneflowers (start indoors), Bee balm (start indoors)
April
Potatoes (plant), Watermelon (start indoors), Peas (plant), Lettuce (start indoors), Lettuce (plant), Spinach (plant), Kale (plant), Broccoli (plant), Cauliflower (plant), Cabbage (plant), Brussels sprouts (plant), Carrots (plant), Beets (plant), Radishes (plant), Onions (plant), Asparagus (plant), Cilantro (plant), Strawberries (plant), Blueberries (plant), Blackberries (plant), Dahlias (start indoors), Caladiums (start indoors), Rose bushes (plant), Foxglove (plant), Hostas (plant), Wildflower seeds (plant)
May
Tomatoes (plant), Bell peppers (plant), Pumpkins (plant), Cucumbers (plant), Okra (plant), Zucchini (plant), Watermelon (plant), Green beans (plant), Sweet corn (plant), Basil (plant), Dill (plant), Sage (plant), Lavender (plant), Borage (plant), Catmint (plant), Gladiolus (plant), Dahlias (plant), Begonias (plant), Coleus (plant), Marigolds (plant), Zinnias (plant), Sunflowers (plant), Cosmos (plant), Mums (plant), Lantana (plant), Hydrangeas (plant), Coneflowers (plant), Bee balm (plant), Sedum (plant), Jasmine (plant)
June
Sweet potatoes (plant), Broccoli (plant for fall), Cauliflower (plant for fall), Cabbage (plant for fall), Brussels sprouts (plant for fall), Caladiums (plant), Grass seed (plant)
July
Green beans (plant for fall), Peas (plant for fall), Kale (plant for fall), Carrots (plant for fall), Beets (plant for fall), Lavender (plant for fall), Iris (plant), Grass seed (plant for fall)
August
Lettuce (plant for fall), Spinach (plant for fall), Radishes (plant for fall), Cilantro (plant for fall), Sage (plant for fall), Catmint (plant for fall), Strawberries (plant for fall), Blueberries (plant for fall), Mums (plant for fall), Hydrangeas (plant for fall), Rose bushes (plant for fall), Peonies (plant), Foxglove (plant for fall), Coneflowers (plant for fall), Bee balm (plant for fall), Hostas (plant for fall), Sedum (plant for fall)
September
Garlic (plant), Tulips (plant), Daffodils (plant), Wildflower seeds (plant for fall)
Zone 4b planting dates for every plant
| Plant | Start indoors | Plant outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Mar 18 – Apr 1 | May 20 – Jun 3 | – |
| Bell peppers | Mar 4 – Mar 18 | May 27 – Jun 10 | – |
| Potatoes | – | Apr 15 – May 6 | – |
| Pumpkins | – | May 20 – Jun 3 | – |
| Cucumbers | – | May 20 – Jun 3 | – |
| Okra | – | May 27 – Jun 17 | – |
| Zucchini | – | May 20 – Jun 3 | – |
| Watermelon | Apr 15 – Apr 22 | May 27 – Jun 10 | – |
| Green beans | – | May 20 – Jun 3 | Jul 14 – Jul 28 |
| Sweet corn | – | May 20 – Jun 3 | – |
| Sweet potatoes | – | Jun 3 – Jun 17 | – |
| Peas | – | Apr 1 – Apr 22 | Jul 7 – Jul 28 |
| Lettuce | Apr 1 – Apr 15 | Apr 15 – May 6 | Aug 4 – Aug 25 |
| Spinach | – | Apr 1 – Apr 22 | Aug 4 – Aug 25 |
| Kale | Mar 18 – Apr 1 | Apr 8 – Apr 29 | Jul 7 – Jul 28 |
| Broccoli | Mar 18 – Apr 1 | Apr 22 – May 6 | Jun 30 – Jul 21 |
| Cauliflower | Mar 18 – Apr 1 | Apr 29 – May 13 | Jun 30 – Jul 21 |
| Cabbage | Mar 18 – Apr 1 | Apr 15 – Apr 29 | Jun 23 – Jul 14 |
| Brussels sprouts | Mar 18 – Apr 1 | Apr 22 – May 6 | Jun 9 – Jun 30 |
| Carrots | – | Apr 22 – May 13 | Jul 7 – Jul 21 |
| Beets | – | Apr 15 – May 6 | Jul 21 – Aug 4 |
| Radishes | – | Apr 1 – Apr 29 | Aug 18 – Sep 1 |
| Onions | Mar 4 – Mar 18 | Apr 15 – Apr 29 | – |
| Garlic | – | – | Sep 29 – Oct 27 |
| Asparagus | – | Apr 15 – May 6 | – |
| Basil | Mar 18 – Apr 1 | May 20 – Jun 3 | – |
| Cilantro | – | Apr 29 – May 20 | Aug 4 – Sep 1 |
| Dill | – | May 13 – May 27 | – |
| Sage | Mar 18 – Apr 1 | May 13 – Jun 3 | Aug 4 – Aug 18 |
| Lavender | Feb 18 – Mar 4 | May 20 – Jun 10 | Jul 21 – Aug 4 |
| Borage | – | May 13 – May 27 | – |
| Catmint | – | May 13 – Jun 3 | Aug 4 – Aug 18 |
| Strawberries | – | Apr 15 – May 6 | Aug 18 – Sep 1 |
| Blueberries | – | Apr 15 – May 6 | Aug 4 – Sep 1 |
| Blackberries | – | Apr 15 – May 6 | – |
| Tulips | – | – | Sep 15 – Oct 27 |
| Daffodils | – | – | Sep 1 – Oct 13 |
| Gladiolus | – | May 13 – May 27 | – |
| Dahlias | Apr 1 – Apr 15 | May 20 – Jun 3 | – |
| Caladiums | Apr 1 – Apr 15 | Jun 3 – Jun 17 | – |
| Begonias | Feb 18 – Mar 18 | May 20 – Jun 3 | – |
| Coleus | Mar 4 – Mar 18 | May 27 – Jun 10 | – |
| Marigolds | Mar 18 – Apr 1 | May 13 – May 27 | – |
| Zinnias | – | May 20 – Jun 3 | – |
| Sunflowers | – | May 20 – Jun 3 | – |
| Cosmos | – | May 13 – May 27 | – |
| Mums | – | May 13 – Jun 3 | Aug 4 – Aug 18 |
| Lantana | – | May 27 – Jun 10 | – |
| Hydrangeas | – | May 13 – May 27 | Aug 4 – Aug 18 |
| Rose bushes | – | Apr 15 – May 13 | Aug 4 – Aug 18 |
| Peonies | – | – | Aug 18 – Sep 29 |
| Iris | – | – | Jul 21 – Aug 18 |
| Foxglove | Mar 4 – Mar 18 | Apr 29 – May 20 | Aug 4 – Aug 18 |
| Coneflowers | Mar 4 – Mar 18 | May 13 – Jun 3 | Aug 4 – Aug 18 |
| Bee balm | Mar 4 – Mar 18 | May 13 – Jun 3 | Aug 4 – Aug 18 |
| Hostas | – | Apr 29 – May 27 | Aug 18 – Sep 1 |
| Sedum | – | May 13 – Jun 3 | Aug 4 – Aug 18 |
| Jasmine | – | May 27 – Jun 10 | – |
| Wildflower seeds | – | Apr 15 – May 6 | Sep 29 – Nov 10 |
| Grass seed | – | Jun 10 – Jul 8 | Jul 28 – Aug 18 |
Places in zone 4b
Weather stations used for this zone include . Mary 1 Ssw, MT; Aberdeen 35 Wnw, SD; Alamosa San Luis, CO; Alexandria, MN; Baker, MT; Barre Montpelier, VT; Berlin, NH; Buffalo, SD; Buffalo 13 Ese, SD; Canton 4 Se, NY; Cloud, MN; Dillon, MT; Duluth, MN; Eau Claire, WI; Faith, SD; Frenchville Aroostook, ME; Great Falls, MT; Greenville Maine Forestry Svc, ME; Greybull S Big Horn, WY; Gulkana, AK; Helena, MT; Hettinger, ND; Houlton, ME; Huron, SD and 31 more.
Zone 4b frost dates by state: Alaska · Colorado · Idaho · Maine · Michigan · Minnesota · Montana · New Hampshire · New York · North Dakota · South Dakota · Vermont · Wisconsin · Wyoming
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