Planting Zone 4b
Min winter temp -25 to -20°F · last frost ~May · first frost ~September
In Zone 4b, the average last spring frost is around May and the first fall frost around September, about a 146-day growing season. Start tender crops indoors before the last frost and move them out once it passes.
Zone 4b planting schedule and calendar
| Crop | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tomatoes | ● | ● | ● | |||||||||
| Peppers | ● | ● | ● | |||||||||
| Cucumbers | ● | ● | ● | |||||||||
| Lettuce | ● | ● | ||||||||||
| Zucchini | ● | ● | ● | |||||||||
| Carrots | ● | ● | ||||||||||
| Beans (bush) | ● | ● | ||||||||||
| Peas | ● | ● | ||||||||||
| Broccoli | ● | ● | ● | |||||||||
| Spinach | ● | ● | ||||||||||
| Kale | ● | ● | ● | |||||||||
| Onions | ● | ● | ● | |||||||||
| Garlic | ||||||||||||
| Potatoes | ● | ● | ||||||||||
| Squash (winter) | ● | ● | ● | |||||||||
| Corn | ● | ● | ||||||||||
| Radishes | ● | ● | ||||||||||
| Beets | ● | ● | ||||||||||
| Eggplant | ● | ● | ● | |||||||||
| Basil | ● | ● | ● | |||||||||
| Cilantro | ● | ● | ||||||||||
| Parsley | ● | ● | ● | |||||||||
| Pumpkins | ● | ● | ● | |||||||||
| Sunflowers | ● | ● |
What to plant this fall in Zone 4b
Fall planting in Zone 4b is arithmetic, not guesswork. The average first frost lands around September 28, so a crop needs its days to maturity, plus about two weeks for the slower growth of shortening days, to fit before then. Hardy crops get some of that back because they keep going past a light frost.
| Crop | Sow by | Fall harvest | Days to harvest |
|---|---|---|---|
| Radishes | Sep 7 | Oct 5 | ~28 |
| Cilantro | Aug 14 | Sep 28 | ~45 |
| Kale | Aug 13 | Oct 12 | ~60 |
| Beets | Aug 11 | Oct 5 | ~55 |
| Lettuce | Aug 9 | Sep 28 | ~50 |
| Carrots | Aug 3 | Oct 12 | ~70 |
| Broccoli | Aug 1 | Oct 5 | ~65 |
| Peas | Jul 30 | Sep 28 | ~60 |
| Zucchini | Jul 7 | Aug 31 | ~55 |
| Beans (bush) | Jul 7 | Aug 31 | ~55 |
| Cucumbers | Jul 2 | Aug 31 | ~60 |
Planted in fall to stand through a Zone 4b winter: garlic (Sep 28 to Oct 26) , onions (Aug 17 to Sep 7) , spinach (Aug 17 to Aug 31) , parsley (Aug 17 to Aug 31) .
More on the method: the fall planting calendar by zone, when to plant garlic and how to stretch your first frost date.
When to plant popular crops in Zone 4b
Tomatoes
~75 days
When to plant
Peppers
~80 days
When to plant
Cucumbers
~60 days
When to plant
Lettuce
~50 days
When to plantCities in Zone 4b, with their own local frost dates: Minneapolis, MN frost dates .
Seasonal reading for Zone 4b
- What to plant in October by zone
The October sowing and planting list for Zone 4b.
- What to plant in November by zone
What still goes in the ground in November in Zone 4b.
- Cold frame gardening by zone
How many weeks a cold frame adds to the Zone 4b season, and what to grow in it.
- October garden checklist
The jobs to finish before the first hard freeze in Zone 4b.
- Houseplants for low light
Something to grow while the Zone 4b garden is frozen.
- Winter sowing guide
Winter sowing dates for Zone 4b.
- When to start seeds indoors by zone
Indoor seed-starting dates counted from the Zone 4b last frost.
- What changed in the 2023 USDA zone map
Whether the 2023 USDA map moved Zone 4b, and what that changes.
- Companion planting chart
Which crops to plant together once you know your dates.
Nearby zones
Frequently asked questions
When is the last frost in Zone 4b?
On average, the last spring frost in Zone 4b is around May; the first fall frost is around September.
What can I grow in Zone 4b?
Nearly all common vegetables and herbs grow in Zone 4b; the difference is timing. Use the planting calendar above, calculated from Zone 4b frost dates.
What can I plant in the fall in Zone 4b?
radishes (sow by Sep 7), cilantro (sow by Aug 14), kale (sow by Aug 13), beets (sow by Aug 11), lettuce (sow by Aug 9), carrots (sow by Aug 3). Each date is counted back from the Zone 4b average first frost around September 28.
How long is the growing season in Zone 4b?
About 146 days between the average last spring and first fall frost.