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Zone 4a planting calendar and frost dates
In USDA hardiness zone 4a, the average last spring frost is May 15 and the average first fall frost is Sep 26, leaving about 134 frost-free days. To be 90% sure of no later frost, wait until about May 28 to plant tender crops. These are medians of 28 NOAA weather stations in zone 4a; their last-frost dates range from May 6 to Jun 24.
What to plant each month in zone 4a
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), 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), Daffodils (plant), 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), Wildflower seeds (plant for fall)
Zone 4a planting dates for every plant
| Plant | Start indoors | Plant outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Mar 20 – Apr 3 | May 22 – Jun 5 | – |
| Bell peppers | Mar 6 – Mar 20 | May 29 – Jun 12 | – |
| Potatoes | – | Apr 17 – May 8 | – |
| Pumpkins | – | May 22 – Jun 5 | – |
| Cucumbers | – | May 22 – Jun 5 | – |
| Okra | – | May 29 – Jun 19 | – |
| Zucchini | – | May 22 – Jun 5 | – |
| Watermelon | Apr 17 – Apr 24 | May 29 – Jun 12 | – |
| Green beans | – | May 22 – Jun 5 | Jul 11 – Jul 25 |
| Sweet corn | – | May 22 – Jun 5 | – |
| Sweet potatoes | – | Jun 5 – Jun 19 | – |
| Peas | – | Apr 3 – Apr 24 | Jul 4 – Jul 25 |
| Lettuce | Apr 3 – Apr 17 | Apr 17 – May 8 | Aug 1 – Aug 22 |
| Spinach | – | Apr 3 – Apr 24 | Aug 1 – Aug 22 |
| Kale | Mar 20 – Apr 3 | Apr 10 – May 1 | Jul 4 – Jul 25 |
| Broccoli | Mar 20 – Apr 3 | Apr 24 – May 8 | Jun 27 – Jul 18 |
| Cauliflower | Mar 20 – Apr 3 | May 1 – May 15 | Jun 27 – Jul 18 |
| Cabbage | Mar 20 – Apr 3 | Apr 17 – May 1 | Jun 20 – Jul 11 |
| Brussels sprouts | Mar 20 – Apr 3 | Apr 24 – May 8 | Jun 6 – Jun 27 |
| Carrots | – | Apr 24 – May 15 | Jul 4 – Jul 18 |
| Beets | – | Apr 17 – May 8 | Jul 18 – Aug 1 |
| Radishes | – | Apr 3 – May 1 | Aug 15 – Aug 29 |
| Onions | Mar 6 – Mar 20 | Apr 17 – May 1 | – |
| Garlic | – | – | Sep 26 – Oct 24 |
| Asparagus | – | Apr 17 – May 8 | – |
| Basil | Mar 20 – Apr 3 | May 22 – Jun 5 | – |
| Cilantro | – | May 1 – May 22 | Aug 1 – Aug 29 |
| Dill | – | May 15 – May 29 | – |
| Sage | Mar 20 – Apr 3 | May 15 – Jun 5 | Aug 1 – Aug 15 |
| Lavender | Feb 20 – Mar 6 | May 22 – Jun 12 | Jul 18 – Aug 1 |
| Borage | – | May 15 – May 29 | – |
| Catmint | – | May 15 – Jun 5 | Aug 1 – Aug 15 |
| Strawberries | – | Apr 17 – May 8 | Aug 15 – Aug 29 |
| Blueberries | – | Apr 17 – May 8 | Aug 1 – Aug 29 |
| Blackberries | – | Apr 17 – May 8 | – |
| Tulips | – | – | Sep 12 – Oct 24 |
| Daffodils | – | – | Aug 29 – Oct 10 |
| Gladiolus | – | May 15 – May 29 | – |
| Dahlias | Apr 3 – Apr 17 | May 22 – Jun 5 | – |
| Caladiums | Apr 3 – Apr 17 | Jun 5 – Jun 19 | – |
| Begonias | Feb 20 – Mar 20 | May 22 – Jun 5 | – |
| Coleus | Mar 6 – Mar 20 | May 29 – Jun 12 | – |
| Marigolds | Mar 20 – Apr 3 | May 15 – May 29 | – |
| Zinnias | – | May 22 – Jun 5 | – |
| Sunflowers | – | May 22 – Jun 5 | – |
| Cosmos | – | May 15 – May 29 | – |
| Mums | – | May 15 – Jun 5 | Aug 1 – Aug 15 |
| Lantana | – | May 29 – Jun 12 | – |
| Hydrangeas | – | May 15 – May 29 | Aug 1 – Aug 15 |
| Rose bushes | – | Apr 17 – May 15 | Aug 1 – Aug 15 |
| Peonies | – | – | Aug 15 – Sep 26 |
| Iris | – | – | Jul 18 – Aug 15 |
| Foxglove | Mar 6 – Mar 20 | May 1 – May 22 | Aug 1 – Aug 15 |
| Coneflowers | Mar 6 – Mar 20 | May 15 – Jun 5 | Aug 1 – Aug 15 |
| Bee balm | Mar 6 – Mar 20 | May 15 – Jun 5 | Aug 1 – Aug 15 |
| Hostas | – | May 1 – May 29 | Aug 15 – Aug 29 |
| Sedum | – | May 15 – Jun 5 | Aug 1 – Aug 15 |
| Jasmine | – | May 29 – Jun 12 | – |
| Wildflower seeds | – | Apr 17 – May 8 | Sep 26 – Nov 7 |
| Grass seed | – | Jun 12 – Jul 10 | Jul 25 – Aug 15 |
Places in zone 4a
Weather stations used for this zone include Aberdeen, SD; Bethel, AK; Bismarck, ND; Brainerd Crow Wing, MN; Caribou, ME; Cut Bank, MT; Devils Lake Kdlr, ND; Fargo Hector, ND; Garrison, ND; Glasgow, MT; Grand Forks, ND; Grantsburg, WI; Hayward, WI; Jamestown 38 Wsw, ND; Jordan, MT; Laramie, WY; Limestone 4 Nnw, ME; Marie, MT; Minot, ND; Moose 1 Nne, WY; Northgate 5 Ese, ND; Port Alsworth 1 Sw, AK; Sandstone 6 W, MN; Saranac, NY and 4 more.
Zone 4a frost dates by state: Alaska · Maine · Minnesota · Montana · New York · North Dakota · South Dakota · Wisconsin · Wyoming
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