Zone 3b planting calendar
In zone 3b the last spring frost usually comes around May 17 and the first fall frost around September 25: about 130 frost-free days. Here is what to do each month.
Typical frost dates
- Last spring frost
- May 17 Middle half of the zone: May 14 – May 22. Over by May 30 in 9 of 10 years.
- First fall frost
- September 25 Middle half of the zone: Sep 20 – Sep 27. After Sep 11 in 9 of 10 years.
- Frost-free season
- about 130 days
- Coldest winter nights
- -35 to -30 °F
- ZIP codes in the zone
- 204
Most of its weather stations are in Minnesota, North Dakota, Montana and Maine.
Places in zone 3b
Zones measure winter cold, so frost dates still vary from place to place. A few weather stations across the zone:
| Place | State | Last spring frost | First fall frost | Frost-free days |
|---|---|---|---|---|
| Chinook | Montana | May 14 | Sep 23 | 130 |
| Edmore | North Dakota | May 15 | Sep 22 | 128 |
| Fort Assiniboine | Montana | May 15 | Sep 24 | 130 |
| Northome | Minnesota | May 16 | Sep 26 | 131 |
| Cass Lake | Minnesota | May 17 | Sep 26 | 131 |
| Rugby | North Dakota | May 17 | Sep 23 | 129 |
| Clayton Lake | Maine | May 30 | Sep 13 | 106 |
Month by month in zone 3b
Every job for all 60 crops, in the month it starts.
January
A quiet month: order seeds and sketch the beds.
February
March
Start indoors
- Peppers Mar 8–22
- Hot peppers Mar 8–22
- Eggplant Mar 8–22
- Onions Mar 8–22
- Parsley Mar 8–22
- Tomatoes Mar 22 – Apr 5
- Tomatillos Mar 22 – Apr 5
- Cabbage Mar 22 – Apr 5
- Broccoli Mar 22 – Apr 5
- Cauliflower Mar 22 – Apr 5
- Chives Mar 22 – Apr 5
April
Sow outside
- Peas Apr 5–26
- Spinach Apr 5 – May 3
- Kale Apr 5 – May 3
- Arugula Apr 12 – May 10
- Radishes Apr 12 – May 24
- Shallots (shallot sets) Apr 19 – May 3
- Collard greens Apr 19 – May 10
- Kohlrabi Apr 19 – May 10
- Turnips Apr 19 – May 10
- Asparagus (asparagus crowns) Apr 19 – May 10
- Rhubarb (rhubarb crowns) Apr 19 – May 10
- Mustard greens Apr 19 – May 17
- Potatoes (seed potatoes) Apr 19 – May 17
- Lettuce Apr 19 – May 31
- Green onions Apr 19 – May 31
- Bok choy Apr 26 – May 17
- Parsnips Apr 26 – May 24
- Carrots Apr 26 – May 31
- Beets Apr 26 – May 31
May
Sow outside
- Cilantro May 3–31
- Swiss chard May 3 – Jun 7
- Dill May 10 – Jun 7
- Sunflowers May 17 – Jun 14
- Zucchini May 24 – Jun 7
- Zinnias May 24 – Jun 7
- Nasturtiums May 24 – Jun 7
- Cosmos May 24 – Jun 7
- Winter squash May 24 – Jun 14
- Pumpkins May 24 – Jun 14
- Sweet corn May 24 – Jun 14
- Cucumbers May 24 – Jul 10
- Green beans May 24 – Jul 10
- Watermelons May 31 – Jun 14
- Cantaloupes May 31 – Jun 14
- Okra May 31 – Jun 21
Plant out
- Cauliflower May 3–17
- Parsley May 3–31
- Thyme May 3–31
- Mint May 3–31
- Oregano May 10–31
- Sage May 10–31
- Rosemary May 17 – Jun 7
- Lavender May 17 – Jun 7
- Tomatoes May 24 – Jun 7
- Tomatillos May 24 – Jun 7
- Celery May 24 – Jun 7
- Marigolds May 24 – Jun 7
- Peppers May 31 – Jun 14
- Hot peppers May 31 – Jun 14
- Eggplant May 31 – Jun 14
- Basil May 31 – Jun 14
Sow for fall
- Brussels sprouts May 1–22
- Cabbage May 29 – Jun 26
June
Plant out
- Sweet potatoes (sweet potato slips) Jun 7–28
Sow for fall
- Cauliflower Jun 5–26
- Broccoli Jun 5 – Jul 3
Start picking
- Mint Jun 2 – Nov 6
- Kohlrabi Jun 3 – Jul 9
- Bok choy Jun 5 – Jul 11
- Collard greens Jun 13 – Nov 6
- Strawberries Jun 14 – Jul 12
- Beets Jun 15 – Jul 30
- Cilantro Jun 17 – Aug 9
- Parsley Jun 17 – Nov 6
- Thyme Jun 17 – Nov 6
- Cabbage Jun 18 – Aug 1
- Green onions Jun 18 – Aug 14
- Dill Jun 19 – Aug 14
- Broccoli Jun 20 – Aug 5
- Swiss chard Jun 22 – Oct 9
- Marigolds (in bloom) Jun 23 – Sep 25
- Oregano Jun 24 – Nov 6
- Carrots Jun 25 – Aug 19
- Cauliflower Jun 27 – Aug 5
- Basil Jun 30 – Sep 25
July
Sow for fall
- Zucchini Jul 3–17
- Peas Jul 3–17
- Carrots Jul 3–24
- Beets Jul 3–24
- Kale Jul 3–31
- Collard greens Jul 3–31
- Green onions Jul 10–24
- Cilantro Jul 17–31
- Lettuce Jul 17 – Aug 7
- Kohlrabi Jul 17 – Aug 7
- Bok choy Jul 17 – Aug 7
- Spinach Jul 17 – Aug 14
- Turnips Jul 17 – Aug 14
- Arugula Jul 24 – Aug 21
- Mustard greens Jul 24 – Aug 21
Start picking
- Potatoes Jul 3 – Sep 14
- Zucchini Jul 8 – Sep 25
- Nasturtiums (in bloom) Jul 8 – Sep 25
- Sage Jul 9 – Nov 6
- Green beans Jul 13 – Sep 8
- Cucumbers Jul 13 – Sep 18
- Lavender Jul 16 – Sep 10
- Rosemary Jul 16 – Oct 9
- Shallots Jul 18 – Aug 21
- Onions Jul 18 – Aug 31
- Garlic Jul 19 – Aug 9
- Okra Jul 20 – Sep 25
- Tomatoes Jul 23 – Sep 25
- Zinnias (in bloom) Jul 23 – Sep 25
- Cosmos (in bloom) Jul 23 – Sep 25
- Leeks Jul 25 – Nov 6
- Sunflowers (in bloom) Jul 26 – Sep 22
- Sweet corn Jul 28 – Sep 12
- Tomatillos Jul 28 – Sep 25
- Peppers Jul 30 – Sep 25
August
Sow for fall
- Radishes Aug 7–28
Start picking
- Eggplant Aug 4 – Sep 25
- Cantaloupes Aug 9 – Sep 13
- Watermelons Aug 9 – Sep 22
- Hot peppers Aug 9 – Sep 25
- Winter squash Aug 12 – Sep 25
- Celery Aug 17 – Oct 9
- Pumpkins Aug 22 – Sep 25
- Beets Aug 22 – Sep 26
- Arugula Aug 23 – Sep 30
- Mustard greens Aug 23 – Oct 5
- Cabbage Aug 25 – Oct 22
- Bok choy Aug 26 – Oct 1
- Spinach Aug 26 – Oct 3
- Lettuce Aug 26 – Oct 7
- Turnips Aug 26 – Oct 13
- Peas Aug 27 – Sep 25
- Cauliflower Aug 27 – Oct 9
- Broccoli Aug 27 – Oct 19
- Brussels sprouts Aug 29 – Nov 6
- Kohlrabi Aug 31 – Oct 6
- Cilantro Aug 31 – Oct 9
September
Sow for fall
- Garlic (garlic cloves) Sep 11 – Oct 16
Start picking
- Radishes Sep 1–27
- Carrots Sep 1 – Oct 13
- Sweet potatoes Sep 5–25
- Green onions Sep 8 – Oct 20
- Parsnips Sep 11 – Nov 6
October
Nothing new to start; keep picking what is still growing, then clear finished beds and spread compost.
November
Nothing to sow; clean and store the tools and note what grew well.
December
A month to rest the soil and plan next year.