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Zone 3b planting calendar and frost dates
In USDA hardiness zone 3b, the average last spring frost is May 17 and the average first fall frost is Sep 23, leaving about 129 frost-free days. To be 90% sure of no later frost, wait until about May 31 to plant tender crops. These are medians of 9 NOAA weather stations in zone 3b; their last-frost dates range from May 14 to Jun 5.
What to plant each month in zone 3b
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), Cabbage (plant), Brussels sprouts (plant), Carrots (plant), Beets (plant), Radishes (plant), Onions (plant), Asparagus (plant), Strawberries (plant), Blueberries (plant), Blackberries (plant), Dahlias (start indoors), Caladiums (start indoors), Rose bushes (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), Cauliflower (plant), Basil (plant), Cilantro (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), Foxglove (plant), Coneflowers (plant), Bee balm (plant), Hostas (plant), Sedum (plant), Jasmine (plant)
June
Sweet potatoes (plant), Broccoli (plant for fall), Cauliflower (plant for fall), Cabbage (plant for fall), Caladiums (plant), Grass seed (plant)
July
Green beans (plant for fall), Peas (plant for fall), Lettuce (plant for fall), Spinach (plant for fall), Kale (plant for fall), Carrots (plant for fall), Beets (plant for fall), Cilantro (plant for fall), Sage (plant for fall), Lavender (plant for fall), Catmint (plant for fall), Blueberries (plant for fall), Mums (plant for fall), Hydrangeas (plant for fall), Rose bushes (plant for fall), Iris (plant), Foxglove (plant for fall), Coneflowers (plant for fall), Bee balm (plant for fall), Sedum (plant for fall), Grass seed (plant for fall)
August
Radishes (plant for fall), Strawberries (plant for fall), Daffodils (plant), Peonies (plant), Hostas (plant for fall)
September
Garlic (plant), Tulips (plant), Wildflower seeds (plant for fall)
Zone 3b planting dates for every plant
| Plant | Start indoors | Plant outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Mar 22 – Apr 5 | May 24 – Jun 7 | – |
| Bell peppers | Mar 8 – Mar 22 | May 31 – Jun 14 | – |
| Potatoes | – | Apr 19 – May 10 | – |
| Pumpkins | – | May 24 – Jun 7 | – |
| Cucumbers | – | May 24 – Jun 7 | – |
| Okra | – | May 31 – Jun 21 | – |
| Zucchini | – | May 24 – Jun 7 | – |
| Watermelon | Apr 19 – Apr 26 | May 31 – Jun 14 | – |
| Green beans | – | May 24 – Jun 7 | Jul 8 – Jul 22 |
| Sweet corn | – | May 24 – Jun 7 | – |
| Sweet potatoes | – | Jun 7 – Jun 21 | – |
| Peas | – | Apr 5 – Apr 26 | Jul 1 – Jul 22 |
| Lettuce | Apr 5 – Apr 19 | Apr 19 – May 10 | Jul 29 – Aug 19 |
| Spinach | – | Apr 5 – Apr 26 | Jul 29 – Aug 19 |
| Kale | Mar 22 – Apr 5 | Apr 12 – May 3 | Jul 1 – Jul 22 |
| Broccoli | Mar 22 – Apr 5 | Apr 26 – May 10 | Jun 24 – Jul 15 |
| Cauliflower | Mar 22 – Apr 5 | May 3 – May 17 | Jun 24 – Jul 15 |
| Cabbage | Mar 22 – Apr 5 | Apr 19 – May 3 | Jun 17 – Jul 8 |
| Brussels sprouts | Mar 22 – Apr 5 | Apr 26 – May 10 | – |
| Carrots | – | Apr 26 – May 17 | Jul 1 – Jul 15 |
| Beets | – | Apr 19 – May 10 | Jul 15 – Jul 29 |
| Radishes | – | Apr 5 – May 3 | Aug 12 – Aug 26 |
| Onions | Mar 8 – Mar 22 | Apr 19 – May 3 | – |
| Garlic | – | – | Sep 23 – Oct 21 |
| Asparagus | – | Apr 19 – May 10 | – |
| Basil | Mar 22 – Apr 5 | May 24 – Jun 7 | – |
| Cilantro | – | May 3 – May 24 | Jul 29 – Aug 26 |
| Dill | – | May 17 – May 31 | – |
| Sage | Mar 22 – Apr 5 | May 17 – Jun 7 | Jul 29 – Aug 12 |
| Lavender | Feb 22 – Mar 8 | May 24 – Jun 14 | Jul 15 – Jul 29 |
| Borage | – | May 17 – May 31 | – |
| Catmint | – | May 17 – Jun 7 | Jul 29 – Aug 12 |
| Strawberries | – | Apr 19 – May 10 | Aug 12 – Aug 26 |
| Blueberries | – | Apr 19 – May 10 | Jul 29 – Aug 26 |
| Blackberries | – | Apr 19 – May 10 | – |
| Tulips | – | – | Sep 9 – Oct 21 |
| Daffodils | – | – | Aug 26 – Oct 7 |
| Gladiolus | – | May 17 – May 31 | – |
| Dahlias | Apr 5 – Apr 19 | May 24 – Jun 7 | – |
| Caladiums | Apr 5 – Apr 19 | Jun 7 – Jun 21 | – |
| Begonias | Feb 22 – Mar 22 | May 24 – Jun 7 | – |
| Coleus | Mar 8 – Mar 22 | May 31 – Jun 14 | – |
| Marigolds | Mar 22 – Apr 5 | May 17 – May 31 | – |
| Zinnias | – | May 24 – Jun 7 | – |
| Sunflowers | – | May 24 – Jun 7 | – |
| Cosmos | – | May 17 – May 31 | – |
| Mums | – | May 17 – Jun 7 | Jul 29 – Aug 12 |
| Lantana | – | May 31 – Jun 14 | – |
| Hydrangeas | – | May 17 – May 31 | Jul 29 – Aug 12 |
| Rose bushes | – | Apr 19 – May 17 | Jul 29 – Aug 12 |
| Peonies | – | – | Aug 12 – Sep 23 |
| Iris | – | – | Jul 15 – Aug 12 |
| Foxglove | Mar 8 – Mar 22 | May 3 – May 24 | Jul 29 – Aug 12 |
| Coneflowers | Mar 8 – Mar 22 | May 17 – Jun 7 | Jul 29 – Aug 12 |
| Bee balm | Mar 8 – Mar 22 | May 17 – Jun 7 | Jul 29 – Aug 12 |
| Hostas | – | May 3 – May 31 | Aug 12 – Aug 26 |
| Sedum | – | May 17 – Jun 7 | Jul 29 – Aug 12 |
| Jasmine | – | May 31 – Jun 14 | – |
| Wildflower seeds | – | Apr 19 – May 10 | Sep 23 – Nov 4 |
| Grass seed | – | Jun 14 – Jul 12 | Jul 22 – Aug 12 |
Places in zone 3b
Weather stations used for this zone include Baudette, MN; Big Delta, AK; Goodridge 12 Nnw, MN; Grand Marais, MN; Havre, MT; Hibbing Chisholm Hibbing, MN; Nome, AK; Park Rapids, MN; Pembina, ND.
Zone 3b frost dates by state: Alaska · Minnesota · Montana · North Dakota
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