Planting Zone 3b
Min winter temp -35 to -30°F · last frost ~May · first frost ~September
In Zone 3b, the average last spring frost is around May and the first fall frost around September, about a 128-day growing season. Start tender crops indoors before the last frost and move them out once it passes.
Zone 3b 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 3b
Fall planting in Zone 3b is arithmetic, not guesswork. The average first frost lands around September 18, 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 | Aug 28 | Sep 25 | ~28 |
| Cilantro | Aug 4 | Sep 18 | ~45 |
| Kale | Aug 3 | Oct 2 | ~60 |
| Beets | Aug 1 | Sep 25 | ~55 |
| Lettuce | Jul 30 | Sep 18 | ~50 |
| Carrots | Jul 24 | Oct 2 | ~70 |
| Broccoli | Jul 22 | Sep 25 | ~65 |
| Peas | Jul 20 | Sep 18 | ~60 |
Planted in fall to stand through a Zone 3b winter: garlic (Sep 18 to Oct 16) , onions (Aug 7 to Aug 28) , spinach (Aug 7 to Aug 21) , parsley (Aug 7 to Aug 21) .
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 3b
Tomatoes
~75 days
When to plant
Peppers
~80 days
When to plant
Cucumbers
~60 days
When to plant
Lettuce
~50 days
When to plantSeasonal reading for Zone 3b
- What to plant in October by zone
The October sowing and planting list for Zone 3b.
- What to plant in November by zone
What still goes in the ground in November in Zone 3b.
- Cold frame gardening by zone
How many weeks a cold frame adds to the Zone 3b season, and what to grow in it.
- October garden checklist
The jobs to finish before the first hard freeze in Zone 3b.
- Houseplants for low light
Something to grow while the Zone 3b garden is frozen.
- Winter sowing guide
Winter sowing dates for Zone 3b.
- When to start seeds indoors by zone
Indoor seed-starting dates counted from the Zone 3b last frost.
- What changed in the 2023 USDA zone map
Whether the 2023 USDA map moved Zone 3b, 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 3b?
On average, the last spring frost in Zone 3b is around May; the first fall frost is around September.
What can I grow in Zone 3b?
Nearly all common vegetables and herbs grow in Zone 3b; the difference is timing. Use the planting calendar above, calculated from Zone 3b frost dates.
What can I plant in the fall in Zone 3b?
radishes (sow by Aug 28), cilantro (sow by Aug 4), kale (sow by Aug 3), beets (sow by Aug 1), lettuce (sow by Jul 30), carrots (sow by Jul 24). Each date is counted back from the Zone 3b average first frost around September 18.
How long is the growing season in Zone 3b?
About 128 days between the average last spring and first fall frost.