Brought to you by garden.gg Zone 4b Planting Calendar & Schedule
Zone 4 is a cold continental climate with long, freezing winters (annual minimum temperatures of -30 to -20 F) and a short, often variable growing season of about four months. Hard frosts persist into late spring and return by mid-September, making variety selection and season extension essential.
Zone 4b is the warmer half of USDA zone 4, where the average coldest winter night bottoms out at −25 to −20°F. Compared with the zone 4 averages, the last spring frost in zone 4b comes about a week earlier (May 18) and the first fall frost about a week later (Sep 22), for a growing season of about 127 days. Every planting window on this page is shifted to match: spring sowing and transplant dates move a week earlier, fall plantings a week later. Crop notes still quote zone 4 timing.
Zone 4 spans much of Montana and North Dakota, northern Minnesota and Wisconsin, Upper Michigan, the Adirondacks, and the mountain valleys of Vermont and New Hampshire, with winter lows of -30 to -20°F. Its 113-day season is the first that reliably ripens main-season tomatoes and peppers from transplants. Winter squash and melons still need the shortest-season varieties available, started indoors in early May.
States & regions in Zone 4: Northern Minnesota, Northern Wisconsin, Northern Maine, Upper Michigan, Montana (much of the state), North Dakota, Northern New York / Adirondacks, Vermont & New Hampshire mountains, Wyoming valleys, Northern Iowa
The sweet spot of northern gardening.
Zone 4 gives you just enough season to grow the classics — tomatoes, peppers, corn — but you need to be strategic. Start indoors early, harden off carefully, and know exactly when your last frost hits. No room for winging it.
Pro tip: Succession plant lettuce and radishes every 2 weeks from April through August. You'll never run out of salad greens.
Save a planting for your zone 4b garden — free
What to Plant in Zone 4b This Fall (September–November)
The average first fall frost in zone 4b is Sep 22. To find the last safe planting date for any fall crop, count back from that date by its days to maturity plus a 14-day fall factor — growth slows as days shorten and soil cools. Applied to zone 4b's frost date, that gives these plant-by dates:
Plant by Aug 9
30 days to maturity + 14-day fall factor
Plant by Jul 25
45 days to maturity + 14-day fall factor
Plant by Jul 20
50 days to maturity + 14-day fall factor
Plant by Jul 15
55 days to maturity + 14-day fall factor
Zone 4a and 4b: these dates count back from zone 4b's first frost, which is about a week later than the zone 4 average of Sep 15. Zone 4a gardeners have about two weeks less fall time — see the zone 4a fall dates.
Fall crops on this zone 4b calendar include Spinach, Lettuce, Arugula, Radish, Mustard Greens, Mizuna, Tatsoi, Bok Choy / Pak Choi, Napa Cabbage, Kale, Turnip, Rutabaga, and 4 more. Each crop's sowing and transplant window is in the fall planting section below.
For month-by-month detail, see what to plant in October across every zone, what to plant in September, and the fall vegetable planting guide by zone.
What to Plant by Season in Zone 4b
The right crops and methods for each season, based on zone 4b's climate and frost timing.
What to Plant in Spring
Spring is short and the soil is slow to warm. The real work begins indoors in late winter under lights, with cold-hardy greens and roots direct-sown outdoors as soon as soil is workable in April-early May, well ahead of the late-May last frost.
Mar 14 - Apr 23
Start 6-8 weeks before last frost; do not transplant out until after May 25.
Mar 4 - Apr 23
Slow to start; sow 8-10 weeks before last frost with bottom heat.
Mar 4 - Apr 23
Needs warmth and a long start; choose short-season varieties.
Mar 14 - Apr 23
Start with tomatoes; plant at least two for pollination.
Mar 14 - Apr 23
Slow germinator; start 8 weeks early.
Feb 14 - Mar 24
Long-day types for the north; start 10-12 weeks early or use sets in May.
Feb 14 - Mar 24
Very long season; start early indoors.
Feb 22 - Apr 23
Slow; needs steady warmth and moisture to germinate.
Feb 22 - Apr 23
Long season; start 10 weeks before transplanting.
Mar 14 - Apr 23
Transplant out mid-May; tolerates light frost.
Mar 14 - Apr 23
Start indoors for an early summer crop.
Mar 14 - Apr 23
Hardy transplant; can set out before last frost.
Mar 14 - Apr 23
Long season; start early to mature before hard fall freezes.
Mar 25 - Apr 23
Can also be direct-sown in early May.
Mar 25 - Apr 23
Prone to bolting; a fall crop is often more reliable.
Apr 4 - May 3
Very cold tolerant; trellis tall types.
Apr 4 - May 3
Direct sow early; declines in summer heat.
Apr 4 - May 3
Very frost hardy; plant as soon as soil thaws.
Apr 4 - May 24
Direct sow early; bolts in heat.
Apr 4 - May 24
Succession sow every 2 weeks; tolerates light frost.
Apr 4 - May 24
Fast and cold-tolerant.
Apr 4 - May 24
Quick cool-season green.
Apr 4 - May 24
Quick crop; ready in 25-30 days.
Apr 14 - May 24
Sow once soil reaches 45 F; keep evenly moist.
Apr 14 - May 24
Tolerates frost; thin seedlings.
Mar 25 - May 24
Fast cool-season root.
Mar 25 - May 24
Slow germinator; needs the full season, sweetens after frost.
Apr 14 - May 24
Plant seed potatoes ~2 weeks before last frost; hill as they grow.
Apr 14 - May 24
Plant sets in early spring for summer harvest.
Mar 25 - May 24
Very hardy; flavor improves with frost.
Apr 14 - May 24
Heat and cold tolerant; long harvest.
Mar 25 - May 24
Hardy brassica green; tolerates frost.
Mar 25 - May 24
Bolts in heat; succession sow.
Mar 25 - May 24
Direct sow; self-seeds readily.
Feb 22 - Apr 23
Slow to germinate; soak seed first.
Mar 25 - May 24
Hardy perennial; returns each spring.
Apr 14 - May 24
Plant crowns; perennial bed, no harvest year one.
Mar 25 - May 24
Plant crowns; cold-loving perennial ideal for zone 4.
Mar 25 - May 24
Set out bare-root crowns; mulch for winter survival.
Mar 25 - May 24
Cold-tolerant; direct sow early.
Mar 25 - May 24
Loves cool weather; sow as soon as soil is workable.
Feb 22 - Apr 23
Frost tolerant; start early for long bloom.
Mar 25 - May 24
Hardy perennial green.
Mar 25 - May 24
Extremely cold hardy salad green.
What to Plant in Summer
Summer is the brief warm window (June-August) when frost-tender crops finally go in the ground. After the May 25 last frost, transplant heat-lovers and direct-sow warm-season crops quickly, since first frost returns by mid-September.
May 14 - Jun 3
Harden off; protect from any late frost with row cover.
May 25 - Jun 3
Wait for warm soil and settled nights above 50 F.
May 25 - Jun 3
Needs the warmest spot; black plastic mulch helps.
May 14 - Jun 3
Vigorous; give cages and space.
May 14 - Jun 3
Sprawling; harvest fallen husks when papery.
May 25 - Jun 13
Direct sow in warm soil or transplant; trellis to save space.
May 25 - Jun 13
Direct sow after frost; very productive.
May 25 - Jun 13
Harvest young and often.
May 25 - Jun 3
Choose short-season varieties; needs full season to cure.
May 25 - Jun 3
Pick early-maturing types for zone 4 (90-100 days).
May 25 - Jun 3
Compact pie types fit the short season well.
May 25 - Jun 13
Use transplants and black plastic; choose 70-75 day varieties.
May 25 - Jun 13
Only short-season icebox types reliably ripen; use transplants.
May 14 - Jun 3
Sow in blocks for pollination; choose early varieties.
May 25 - Jun 13
Direct sow in warm soil; succession sow for steady harvest.
May 25 - Jun 13
Trellis; longer harvest than bush types.
May 25 - Jun 13
Choose early varieties for a single harvest.
May 25 - Jun 13
Tolerates cool nights better than common beans; ornamental too.
May 25 - Jun 13
Very frost-sensitive; wait until nights are warm.
May 25 - Jun 3
Warm-season annual herb.
May 25 - Jun 3
Heat-loving green; sow in warm soil.
May 14 - Jun 23
Direct sow; choose shorter-season varieties for seed heads.
May 14 - Jun 23
Edible flowers; thrives in poor soil.
May 14 - Jun 23
Plant after frost; deters some pests.
May 14 - Jun 23
Heat-loving cut flower; sow after frost.
May 14 - Jun 23
Easy from seed; long bloom.
May 14 - Jun 23
Bee magnet; self-seeds.
May 25 - Jul 24
Sow heat-tolerant types in light shade through summer.
May 25 - Jun 23
A June sowing yields a fall storage crop.
May 25 - Jun 23
Sow again in June for fall harvest.
What to Plant in Fall
Fall comes early and fast in zone 4, with first frost around September 15. The focus is harvesting and curing storage crops, plus quick cold-hardy greens and roots sown in mid-to-late summer that mature or sweeten as temperatures drop. Plant garlic in October for next year.
Aug 8 - Sep 7
Late-summer sowing yields a fall crop and can overwinter under mulch.
Aug 8 - Sep 7
Cool-season comeback crop; protect from early frost with row cover.
Aug 8 - Sep 17
Fast and frost-tolerant; great for fall.
Aug 8 - Sep 17
Quick fall crop before hard freeze.
Aug 8 - Sep 7
Cool-weather green; pungency mellows with frost.
Aug 8 - Sep 7
Fast Asian green; cold tolerant.
Aug 8 - Sep 7
Very cold hardy rosette green.
Aug 8 - Sep 7
Less likely to bolt sown in late summer for fall.
Jul 28 - Aug 17
More reliable as a fall crop than spring.
Jun 24 - Aug 24
Sweetens markedly after fall frosts; very hardy.
Jun 24 - Aug 3
Fall roots and greens; frost improves flavor.
May 25 - Jul 3
Long-season storage root; harvest after first frosts.
Jul 28 - Sep 7
Fall storage radish; harvest before ground freezes.
Aug 8 - Oct 7
Extremely hardy; can be harvested through hard frost and snow.
Aug 8 - Oct 7
Cold-hardy winter salad green under cover.
Oct 8 - Nov 7
Plant cloves 3-4 weeks before ground freezes; mulch heavily for next-summer harvest.
What to Plant in Winter
Outdoor planting in zone 4 winter is effectively nil — the ground is frozen and snow-covered from roughly November through March. Winter is for indoor seed-starting under lights, garden planning and seed ordering, and protecting overwintering crops (mulched garlic, parsnips, cold-frame greens).
Feb 14 - Feb 21
Long-day onions need the earliest indoor start of the season.
Feb 14 - Feb 21
Start under lights; very long season crop.
Feb 14 - Mar 24
Begin slow-growing peppers indoors with bottom heat.
Jan 25 - Mar 24
Needs a long warm start indoors.
Jan 25 - Mar 24
Slow; start very early under lights.
Save a planting from your zone 4 calendar
Choose a crop and a date that suits your local conditions. Create a free account or sign in, then review and save your planting plan. Your saved plan is available on web, iOS, and Android.
Zone calendars are starting points, not local forecasts. Check local frost dates, soil temperature, and the crop's planting instructions before choosing a date. This does not change your profile's zone.
Full Planting Timing Table
Start-indoors, direct-sow, transplant, and harvest windows for every crop in zone 4b.
Vegetables
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Amaranth (Leaf) | — | May 25 - Jun 3 | — | — | Heat-loving green; sow in warm soil. |
| Arugula | — | Apr 4 - May 24 | — | — | Fast and frost-tolerant; great for fall. |
| Asparagus | — | — | Apr 14 - May 24 | — | Plant crowns; perennial bed, no harvest year one. |
| Beet | — | Apr 14 - May 24 | — | Sep 8 - Nov 7 | Tolerates frost; thin seedlings. |
| Bok Choy / Pak Choi | — | Aug 8 - Sep 7 | — | — | Less likely to bolt sown in late summer for fall. |
| Broccoli | Mar 14 - Apr 23 | — | — | — | Transplant out mid-May; tolerates light frost. |
| Brussels Sprouts | Mar 14 - Apr 23 | — | — | Sep 8 - Nov 7 | Long season; start early to mature before hard fall freezes. |
| Bush Bean | — | May 25 - Jun 13 | — | — | Direct sow in warm soil; succession sow for steady harvest. |
| Cabbage | Mar 14 - Apr 23 | — | — | — | Hardy transplant; can set out before last frost. |
| Carrot | — | Apr 14 - May 24 | — | — | Sow once soil reaches 45 F; keep evenly moist. |
| Cauliflower | Mar 14 - Apr 23 | — | — | — | Start indoors for an early summer crop. |
| Celeriac | Feb 22 - Apr 23 | — | — | — | Slow; start very early under lights. |
| Celery | Feb 22 - Apr 23 | — | — | — | Needs a long warm start indoors. |
| Claytonia (Miner's Lettuce) | — | Aug 8 - Oct 7 | — | — | Cold-hardy winter salad green under cover. |
| Collards | — | Mar 25 - May 24 | — | — | Hardy brassica green; tolerates frost. |
| Corn (Sweet) | — | May 14 - Jun 3 | — | — | Sow in blocks for pollination; choose early varieties. |
| Cucumber | — | May 25 - Jun 13 | — | — | Direct sow in warm soil or transplant; trellis to save space. |
| Daikon Radish | — | Jul 28 - Sep 7 | — | — | Fall storage radish; harvest before ground freezes. |
| Edamame (Soybean) | — | May 25 - Jun 13 | — | — | Choose early varieties for a single harvest. |
| Eggplant | Mar 4 - Apr 23 | — | May 25 - Jun 3 | — | Needs warmth and a long start; choose short-season varieties. |
| Fava Bean | — | Apr 4 - May 3 | — | — | Very frost hardy; plant as soon as soil thaws. |
| Garden Pea | — | Apr 4 - May 3 | — | — | Very cold tolerant; trellis tall types. |
| Garlic | — | — | Oct 8 - Nov 7 | — | Plant cloves 3-4 weeks before ground freezes; mulch heavily for next-summer harvest. |
| Husk-less / Pie Pumpkin | — | May 25 - Jun 3 | — | — | Compact pie types fit the short season well. |
| Kale | — | Jun 24 - Aug 24 | — | — | Sweetens markedly after fall frosts; very hardy. |
| Kohlrabi | Mar 25 - Apr 23 | — | — | — | Can also be direct-sown in early May. |
| Leek | Feb 14 - Mar 24 | — | — | Sep 8 - Nov 7 | Start under lights; very long season crop. |
| Lettuce | — | Apr 4 - May 24 | — | — | Cool-season comeback crop; protect from early frost with row cover. |
| Mizuna | — | Aug 8 - Sep 7 | — | — | Fast Asian green; cold tolerant. |
| Mustard Greens | — | Apr 4 - May 24 | — | — | Cool-weather green; pungency mellows with frost. |
| Napa Cabbage | Mar 25 - Apr 23 | Jul 28 - Aug 17 | — | — | More reliable as a fall crop than spring. |
| Onion (Bulb) | Feb 14 - Mar 24 | — | — | — | Long-day onions need the earliest indoor start of the season. |
| Pac/Corn Salad (Mâche) | — | Aug 8 - Oct 7 | — | — | Extremely hardy; can be harvested through hard frost and snow. |
| Parsnip | — | Mar 25 - May 24 | — | — | Slow germinator; needs the full season, sweetens after frost. |
| Pepper (Bell & Hot) | Mar 4 - Apr 23 | — | May 25 - Jun 3 | — | Slow to start; sow 8-10 weeks before last frost with bottom heat. |
| Pole Bean | — | May 25 - Jun 13 | — | — | Trellis; longer harvest than bush types. |
| Pole/Runner Bean (Scarlet) | — | May 25 - Jun 13 | — | — | Tolerates cool nights better than common beans; ornamental too. |
| Potato | — | — | Apr 14 - May 24 | Sep 8 - Oct 7 | Plant seed potatoes ~2 weeks before last frost; hill as they grow. |
| Pumpkin | — | May 25 - Jun 3 | — | Sep 8 - Oct 7 | Pick early-maturing types for zone 4 (90-100 days). |
| Radish | — | Apr 4 - May 24 | — | — | Quick fall crop before hard freeze. |
| Rhubarb | — | — | Mar 25 - May 24 | — | Plant crowns; cold-loving perennial ideal for zone 4. |
| Rutabaga | — | May 25 - Jul 3 | — | — | Long-season storage root; harvest after first frosts. |
| Shallot | — | — | Apr 14 - May 24 | — | Plant sets in early spring for summer harvest. |
| Snap / Snow Pea | — | Apr 4 - May 3 | — | — | Direct sow early; declines in summer heat. |
| Spinach | — | Apr 4 - May 24 | — | — | Late-summer sowing yields a fall crop and can overwinter under mulch. |
| Summer Squash | — | May 25 - Jun 13 | — | — | Harvest young and often. |
| Swiss Chard | — | Apr 14 - May 24 | — | Sep 8 - Nov 7 | Heat and cold tolerant; long harvest. |
| Tatsoi | — | Aug 8 - Sep 7 | — | — | Very cold hardy rosette green. |
| Tomatillo | Mar 14 - Apr 23 | — | May 14 - Jun 3 | — | Start with tomatoes; plant at least two for pollination. |
| Tomato | Mar 14 - Apr 23 | — | May 14 - Jun 3 | — | Start 6-8 weeks before last frost; do not transplant out until after May 25. |
| Turnip | — | Jun 24 - Aug 3 | — | — | Fall roots and greens; frost improves flavor. |
| Winter Squash | — | May 25 - Jun 3 | — | Sep 8 - Oct 7 | Choose short-season varieties; needs full season to cure. |
| Zucchini | — | May 25 - Jun 13 | — | — | Direct sow after frost; very productive. |
Herbs
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Basil | — | — | May 25 - Jun 13 | — | Very frost-sensitive; wait until nights are warm. |
| Chives | — | Mar 25 - May 24 | — | — | Hardy perennial; returns each spring. |
| Cilantro / Coriander | — | Mar 25 - May 24 | — | — | Bolts in heat; succession sow. |
| Dill | — | Mar 25 - May 24 | — | — | Direct sow; self-seeds readily. |
| Parsley | Feb 22 - Apr 23 | — | — | — | Slow to germinate; soak seed first. |
| Sorrel | — | Mar 25 - May 24 | — | — | Hardy perennial green. |
| Summer Savory | — | May 25 - Jun 3 | — | — | Warm-season annual herb. |
Fruits
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Ground Cherry | Mar 14 - Apr 23 | — | May 14 - Jun 3 | — | Slow germinator; start 8 weeks early. |
| Muskmelon / Cantaloupe | — | — | May 25 - Jun 13 | — | Use transplants and black plastic; choose 70-75 day varieties. |
| Strawberry | — | — | Mar 25 - May 24 | — | Set out bare-root crowns; mulch for winter survival. |
| Watermelon | — | — | May 25 - Jun 13 | — | Only short-season icebox types reliably ripen; use transplants. |
Flowers
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Borage | — | May 14 - Jun 23 | — | — | Bee magnet; self-seeds. |
| Calendula | — | Mar 25 - May 24 | — | — | Cold-tolerant; direct sow early. |
| Cosmos | — | May 14 - Jun 23 | — | — | Easy from seed; long bloom. |
| Marigold | — | — | May 14 - Jun 23 | — | Plant after frost; deters some pests. |
| Nasturtium | — | May 14 - Jun 23 | — | — | Edible flowers; thrives in poor soil. |
| Snapdragon | Feb 22 - Apr 23 | — | — | — | Frost tolerant; start early for long bloom. |
| Sunflower | — | May 14 - Jun 23 | — | — | Direct sow; choose shorter-season varieties for seed heads. |
| Sweet Pea | — | Mar 25 - May 24 | — | — | Loves cool weather; sow as soon as soil is workable. |
| Zinnia | — | May 14 - Jun 23 | — | — | Heat-loving cut flower; sow after frost. |
Zone 4a vs Zone 4b
USDA divides zone 4 into two half-zones 5°F apart. Zone 4b is the warmer one; here is how its frost dates compare with zone 4a and the zone 4 average.
| Zone 4a | Zone 4 | Zone 4b | |
|---|---|---|---|
| Winter low | −30 to −25°F | −30 to −20°F | −25 to −20°F |
| Last spring frost | Jun 1 | May 25 | May 18 |
| First fall frost | Sep 8 | Sep 15 | Sep 22 |
| Growing season | 99 days | 113 days | 127 days |
Not sure which half you're in? The half-zone comes from your area's average coldest winter night, so check the USDA map for your ZIP code. Your own microclimate — slope, shelter, pavement, elevation — can move dates as much as the half-zone does.
Zone 4b Growing Tips
- ✓ Start warm-season crops (tomatoes, peppers, eggplant, onions, leeks) indoors under grow lights 6-12 weeks before the late-May last frost — direct sowing leaves too little season for them to mature.
- ✓ Choose short-season, cold-adapted varieties: look for tomatoes, melons, corn, and squash rated under 70-90 days to maturity so they finish before the mid-September frost.
- ✓ Use season-extension tools aggressively — row covers, low tunnels, black plastic mulch, and cold frames buy weeks on both ends and let heat-lovers like melons and peppers actually ripen.
- ✓ Plant garlic in October, then mulch heavily (6-8 inches of straw) to prevent frost heaving over the long winter for a strong summer harvest.
- ✓ Lean into cold-hardy crops that thrive here — kale, Brussels sprouts, carrots, parsnips, leeks, and rutabaga sweeten after frost and store or overwinter well under mulch.
- ✓ Watch the wide frost window: the last spring frost can come as late as June 5 and the first fall frost as early as September 5, so keep row cover handy at both ends of the season.
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Sign Up FreeFrequently Asked Questions
What can I plant in spring in zone 4b?
In zone 4b, spring planting includes Tomato, Pepper (Bell & Hot), Eggplant, Tomatillo, Ground Cherry, Onion (Bulb), Leek, Celery, and more. See the spring section above for each crop's timing.
What is the last frost date for zone 4b?
The average last spring frost date for USDA zone 4b is May 18. The first fall frost typically arrives around Sep 22, giving a growing season of approximately 127 days.
When is the first frost in zone 4b?
The average first fall frost in USDA zone 4b arrives around Sep 22. That is an average, not a guarantee — the actual first frost varies by up to 2 weeks either way, so watch your local forecast from a few weeks before that date and have row covers ready for tender crops still in the ground.
When can I start seeds indoors in zone 4b?
In zone 4b, start crops like Tomato indoors around Mar 14 - Apr 23. Check the seasonal sections above for each crop's indoor-sowing window.
What can I plant in fall in zone 4b?
Fall planting in zone 4b includes Spinach, Lettuce, Arugula, Radish, Mustard Greens, Mizuna, Tatsoi, Bok Choy / Pak Choi, and more.
How long is the growing season in zone 4b?
Zone 4b has an average growing season of 127 days, from the last spring frost around May 18 to the first fall frost around Sep 22.
What is the difference between zone 4a and zone 4b?
Zone 4b is the warmer half of USDA zone 4, with average coldest winter nights of −25 to −20°F. Compared with the zone 4 averages (last frost May 25, first frost Sep 15), zone 4b's last spring frost is about a week earlier (May 18) and its first fall frost about a week later (Sep 22), so zone 4a gardeners plant about two weeks later in spring and earlier in fall than zone 4b.
What to plant right now
Month-specific guides for zone 4, hand-tuned to current frost dates and crop windows.
- What to Plant in October: Garlic Month, Cover Crops, and the Southern Fall Garden — What to plant in October: garlic goes in across zones 3-7, cover crops hit their deadline, and zones 8-10 plant the best garden of their year.
Learn more: When to plant vegetables by zone