Brought to you by garden.gg Zone 3b Planting Calendar & Schedule
USDA zone 3 is a cold continental climate with long, harsh winters (annual minimums of -40 to -30°F) and a short, intense growing season of roughly 90-115 frost-free days. Warm spells arrive late and frost returns early, so heat-loving crops require indoor starting and season-extension to mature.
Zone 3b is the warmer half of USDA zone 3, where the average coldest winter night bottoms out at −35 to −30°F. Compared with the zone 3 averages, the last spring frost in zone 3b comes about a week earlier (May 18) and the first fall frost about a week later (Sep 19), for a growing season of about 119 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 3 timing.
Zone 3 takes in Duluth and International Falls, Caribou in northern Maine, the northern plains of North Dakota and Montana, and high-elevation valleys in the Wyoming and Colorado Rockies. Winter lows hit -40°F and the 105-day season leaves no slack: a tomato transplanted a week late may never ripen. The compensation is 16-hour June days that push peas, brassicas, and root crops hard.
States & regions in Zone 3: Northern Minnesota (Duluth, International Falls), Northern North Dakota & Montana (Bismarck, Glasgow), Northern Wisconsin, Interior/northern Maine (Caribou), Northern New Hampshire & Vermont mountains, High-elevation Wyoming & Colorado Rockies, Upper Michigan (interior)
Short season? Make every day count.
With just 120 frost-free days, zone 3 gardeners can't afford to guess. Every week matters when you're racing against September frost. That's why tracking your planting dates, frost alerts, and harvest windows isn't optional — it's survival.
Pro tip: Start seeds indoors in March to get a head start. Use season extenders like cold frames and row covers to squeeze out extra weeks on both ends.
Save a planting for your zone 3b garden — free
What to Plant in Zone 3b This Fall (September–November)
The average first fall frost in zone 3b is Sep 19. 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 3b's frost date, that gives these plant-by dates:
Plant by Aug 6
30 days to maturity + 14-day fall factor
Plant by Jul 27
40 days to maturity + 14-day fall factor
Plant by Jul 22
45 days to maturity + 14-day fall factor
Plant by Jul 17
50 days to maturity + 14-day fall factor
Zone 3a and 3b: these dates count back from zone 3b's first frost, which is about a week later than the zone 3 average of Sep 12. Zone 3a gardeners have about two weeks less fall time — see the zone 3a fall dates.
Fall crops on this zone 3b calendar include Garlic, Spinach, Lettuce, Arugula, Mizuna, Tatsoi, Bok Choy / Pak Choi, Mustard Greens, Radish, Turnip, Pac/Corn Salad (Mâche), Claytonia (Miner's Lettuce). 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 3b
The right crops and methods for each season, based on zone 3b's climate and frost timing.
What to Plant in Spring
Spring in zone 3 is short and unpredictable, with hard frosts possible into early June. Cold-tolerant greens, roots, and brassicas go in as soon as soil can be worked (mid-to-late April), while warm-season crops are started indoors under lights and held until after the last frost.
Feb 14 - Mar 24
Long-day varieties only; start 10-12 weeks before last frost, transplant mid-May.
Feb 14 - Mar 24
Slow to size up; needs the longest possible season.
Feb 22 - Mar 24
Start 10-12 weeks early; transplant after frost danger passes.
Feb 22 - Mar 24
Long-season root; start indoors with celery.
Feb 22 - Apr 3
Start 8-10 weeks before last frost; choose early, short-season varieties.
Feb 22 - Apr 3
Needs bottom heat; pick the earliest cultivars for zone 3.
Mar 14 - Apr 23
Start 6-8 weeks early; favor early determinate/short-season types (e.g. 55-65 day).
Mar 14 - Apr 23
Start with tomatoes; plant at least two for pollination.
Mar 14 - Apr 23
Treat like tomatillo; reliable in short seasons once established.
Mar 14 - Apr 23
Start indoors, transplant early May; tolerates light frost.
Mar 14 - Apr 23
Start indoors; keep growth steady to avoid buttoning.
Mar 14 - Apr 23
Hardy transplant; set out early-to-mid May.
Mar 14 - Apr 23
Long-season; start early so sprouts size up before hard fall frost.
Mar 25 - Apr 23
Can also be direct-sown; transplants give an earlier crop.
Mar 25 - Apr 23
Transplant after frost to reduce bolting risk.
Mar 25 - Apr 23
Very frost-tender; hold indoors until soil and nights warm (June).
Feb 22 - Apr 23
Slow to germinate; start early or direct-sow late April.
Feb 22 - Apr 23
Cold-hardy; transplant early and it shrugs off light frost.
Apr 14 - May 3
Sow as soon as soil is workable; tolerates frost.
Apr 14 - May 3
Very cold-tolerant; one of the earliest sowings.
Apr 14 - May 3
Likes cool weather; sow early before heat.
Apr 14 - May 24
Sow early; bolts fast once days lengthen and warm.
Apr 14 - May 24
Succession-sow every 2 weeks; very frost-tolerant.
Apr 14 - May 24
Fast cool-season green; bolts in summer heat.
Apr 14 - May 24
Quick, cold-hardy; sow as soon as soil works.
Apr 14 - May 24
Matures in 3-4 weeks; ideal early crop.
Apr 24 - May 13
Sow once soil reaches ~45°F; keep seedbed moist.
Apr 24 - May 13
Cold-tolerant; greens and roots both usable.
Apr 14 - May 24
Fast cool-season root; sow early.
Apr 24 - May 13
Slow germinator; needs full season, sweetens after frost.
Apr 14 - May 24
Extremely cold-hardy; direct-sow or transplant.
Apr 24 - May 3
Sow after worst frosts; productive all season.
Apr 24 - May 13
Plant seed potatoes 2-3 weeks before last frost; hill against late frost.
Apr 14 - May 24
Plant sets in early spring for summer harvest.
Apr 14 - May 24
Quick and cold-tolerant; succession-sow.
Apr 14 - May 24
Cool-season; bolts in heat, so sow early and succession.
Apr 24 - May 24
Direct-sow after frost; self-seeds readily.
Apr 14 - May 24
Hardy annual; tolerates cool soil and light frost.
Apr 14 - May 24
Sow early in cool soil; provide support.
What to Plant in Summer
Summer is the prime warm-season window, but it is brief and nights stay cool. After the last frost (late May/early June) set out all heat-lovers and keep succession-sowing fast greens and roots; aim to have warm crops well-established by mid-June to beat the early-September frost.
May 25 - Jun 13
Transplant only after frost risk passes; use Wall O' Water or row cover early.
May 25 - Jun 13
Wait for warm nights (>50°F); black mulch boosts soil heat.
Jun 4 - Jun 13
Most heat-demanding nightshade; cloche or low tunnel helps.
May 25 - Jun 13
Plant in pairs for fruit set.
May 25 - Jun 13
Sprawling; give room and harvest fallen husks.
Jun 4 - Jun 13
Cold-sensitive; do not set out until nights stay above 50°F.
May 25 - Jun 3
Direct-sow in warm soil; very productive in short seasons.
May 25 - Jun 3
Fast-maturing; sow after frost on warm soil.
May 25 - Jun 3
Choose early types (e.g. acorn, buttercup); may also start indoors in May to gain time.
May 25 - Jun 3
Pick short-season varieties; start indoors late May for larger types.
May 25 - Jun 3
Short-season pie pumpkins ripen reliably; cure before storage.
May 25 - Jun 13
Warm soil only; row cover speeds early growth.
May 25 - Jun 3
Choose early/short-season hybrids; sow in blocks for pollination.
May 25 - Jun 13
Frost-tender; sow once soil warms; quick to harvest.
May 25 - Jun 13
Sow on warm soil with a trellis.
May 25 - Jun 13
Pick early-maturing edamame varieties for zone 3.
May 25 - Jun 13
Handles cool nights better than common beans; ornamental too.
Jun 4 - Jun 13
Marginal; start indoors May, transplant onto black plastic + tunnel.
Jun 4 - Jun 13
Only short-season icebox types under plastic/tunnel will ripen.
May 25 - Jun 13
Heat-loving green; sow after soil warms.
May 14 - Jun 23
Direct-sow; choose shorter-season varieties for seed.
May 25 - Jun 13
Frost-tender; start indoors or transplant after last frost.
May 25 - Jun 13
Plant after frost; good pest companion.
May 25 - Jun 3
Easy from direct seed once frost has passed.
May 25 - Jun 3
Direct-sow after frost; edible flowers and leaves.
May 25 - Jun 3
Direct-sow; attracts pollinators, self-seeds.
May 25 - Jul 24
Succession-sow heat-tolerant types in part shade through summer.
May 25 - Jun 23
Second sowing for fall storage.
May 25 - Jun 23
Main storage sowing; harvest after fall frosts for sweetness.
What to Plant in Fall
Fall arrives fast, with the first frost typically around mid-September. The season belongs to cold-hardy greens and roots that sweeten in cool weather, plus garlic planting; protect tender survivors with row cover and harvest storage crops before hard freezes.
Sep 28 - Nov 7
Plant cloves 4-6 weeks before ground freezes; mulch heavily for winter.
Jul 28 - Sep 7
Fall sowing; very frost-hardy and can overwinter under mulch.
Jul 28 - Sep 7
Cool-weather flush; cover during early frosts to extend.
Aug 8 - Sep 7
Fast fall green; flavor improves in cool weather.
Aug 8 - Sep 7
Cold-hardy mustard for fall salads.
Aug 8 - Sep 7
Very cold-tolerant rosette green for fall.
Aug 8 - Sep 7
Fall sowing avoids spring bolting; protect from early frost.
Aug 8 - Sep 7
Quick fall crop; sweeter after light frost.
Aug 8 - Sep 17
Fast fall crop; tolerates frost.
Jul 28 - Sep 7
Roots and greens both improve after frost.
Aug 8 - Oct 7
Extremely cold-hardy; can overwinter under snow.
Aug 8 - Oct 7
Cold-hardy salad green; overwinters in cold frame.
What to Plant in Winter
Winter is not an outdoor growing season in zone 3 — the ground freezes solid and snow cover lasts for months. Work moves indoors: planning the next garden, ordering seed, starting long-season transplants under lights late in the period, and protecting overwintering garlic and perennials under mulch and snow.
Feb 14 - Feb 21
Begin long-day onion seedlings indoors under lights for a May transplant.
Feb 14 - Feb 21
Start indoors with onions; needs the longest lead time.
Feb 14 - Feb 21
Slow grower; sow indoors at winter's end.
Save a planting from your zone 3 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 3b.
Vegetables
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Amaranth (Leaf) | — | May 25 - Jun 13 | — | — | Heat-loving green; sow after soil warms. |
| Arugula | — | Apr 14 - May 24 | — | — | Fast fall green; flavor improves in cool weather. |
| Beet | — | May 25 - Jun 23 | — | Sep 8 - Nov 7 | Cold-tolerant; greens and roots both usable. |
| Bok Choy / Pak Choi | — | Aug 8 - Sep 7 | — | — | Fall sowing avoids spring bolting; protect from early frost. |
| Broccoli | Mar 14 - Apr 23 | — | — | — | Start indoors, transplant early May; tolerates light frost. |
| Brussels Sprouts | Mar 14 - Apr 23 | — | — | Sep 8 - Nov 7 | Long-season; start early so sprouts size up before hard fall frost. |
| Bush Bean | — | May 25 - Jun 13 | — | — | Frost-tender; sow once soil warms; quick to harvest. |
| Cabbage | Mar 14 - Apr 23 | — | — | Sep 8 - Nov 7 | Hardy transplant; set out early-to-mid May. |
| Carrot | — | May 25 - Jun 23 | — | Sep 8 - Nov 7 | Sow once soil reaches ~45°F; keep seedbed moist. |
| Cauliflower | Mar 14 - Apr 23 | — | — | — | Start indoors; keep growth steady to avoid buttoning. |
| Celeriac | Feb 22 - Mar 24 | — | — | — | Long-season root; start indoors with celery. |
| Celery | Feb 22 - Mar 24 | — | — | — | Start 10-12 weeks early; transplant after frost danger passes. |
| Claytonia (Miner's Lettuce) | — | Aug 8 - Oct 7 | — | — | Cold-hardy salad green; overwinters in cold frame. |
| Collards | — | — | — | Sep 8 - Nov 7 | — |
| Corn (Sweet) | — | May 25 - Jun 3 | — | — | Choose early/short-season hybrids; sow in blocks for pollination. |
| Cucumber | — | May 25 - Jun 13 | — | — | Warm soil only; row cover speeds early growth. |
| Edamame (Soybean) | — | May 25 - Jun 13 | — | — | Pick early-maturing edamame varieties for zone 3. |
| Eggplant | Feb 22 - Apr 3 | — | Jun 4 - Jun 13 | — | Most heat-demanding nightshade; cloche or low tunnel helps. |
| Fava Bean | — | Apr 14 - May 3 | — | — | Likes cool weather; sow early before heat. |
| Garden Pea | — | Apr 14 - May 3 | — | — | Sow as soon as soil is workable; tolerates frost. |
| Garlic | — | — | Sep 28 - Nov 7 | — | Plant cloves 4-6 weeks before ground freezes; mulch heavily for winter. |
| Husk-less / Pie Pumpkin | — | May 25 - Jun 3 | — | — | Short-season pie pumpkins ripen reliably; cure before storage. |
| Kale | — | Apr 14 - May 24 | — | Sep 8 - Nov 7 | Extremely cold-hardy; direct-sow or transplant. |
| Kohlrabi | Mar 25 - Apr 23 | — | — | — | Can also be direct-sown; transplants give an earlier crop. |
| Leek | Feb 14 - Mar 24 | — | — | Sep 8 - Nov 7 | Slow to size up; needs the longest possible season. |
| Lettuce | — | Jul 28 - Sep 7 | — | — | Cool-weather flush; cover during early frosts to extend. |
| Mizuna | — | Aug 8 - Sep 7 | — | — | Cold-hardy mustard for fall salads. |
| Mustard Greens | — | Apr 14 - May 24 | — | — | Quick fall crop; sweeter after light frost. |
| Napa Cabbage | Mar 25 - Apr 23 | — | — | — | Transplant after frost to reduce bolting risk. |
| Onion (Bulb) | Feb 14 - Mar 24 | — | — | Sep 8 - Oct 7 | Long-day varieties only; start 10-12 weeks before last frost, transplant mid-May. |
| Pac/Corn Salad (Mâche) | — | Aug 8 - Oct 7 | — | Dec 8 - Mar 7 | Extremely cold-hardy; can overwinter under snow. |
| Parsnip | — | Apr 24 - May 13 | — | — | Slow germinator; needs full season, sweetens after frost. |
| Pepper (Bell & Hot) | Feb 22 - Apr 3 | — | May 25 - Jun 13 | — | Wait for warm nights (>50°F); black mulch boosts soil heat. |
| Pole Bean | — | May 25 - Jun 13 | — | — | Sow on warm soil with a trellis. |
| Pole/Runner Bean (Scarlet) | — | May 25 - Jun 13 | — | — | Handles cool nights better than common beans; ornamental too. |
| Potato | — | — | Apr 24 - May 13 | Sep 8 - Oct 7 | Plant seed potatoes 2-3 weeks before last frost; hill against late frost. |
| Pumpkin | — | May 25 - Jun 3 | — | — | Pick short-season varieties; start indoors late May for larger types. |
| Radish | — | Apr 14 - May 24 | — | — | Fast fall crop; tolerates frost. |
| Rutabaga | — | — | — | Sep 8 - Nov 7 | — |
| Scallion / Green Onion | — | Apr 14 - May 24 | — | — | Quick and cold-tolerant; succession-sow. |
| Shallot | — | — | Apr 14 - May 24 | — | Plant sets in early spring for summer harvest. |
| Snap / Snow Pea | — | Apr 14 - May 3 | — | — | Very cold-tolerant; one of the earliest sowings. |
| Spinach | — | Jul 28 - Sep 7 | — | — | Fall sowing; very frost-hardy and can overwinter under mulch. |
| Summer Squash | — | May 25 - Jun 3 | — | — | Fast-maturing; sow after frost on warm soil. |
| Swiss Chard | — | Apr 24 - May 3 | — | — | Sow after worst frosts; productive all season. |
| Tatsoi | — | Aug 8 - Sep 7 | — | — | Very cold-tolerant rosette green for fall. |
| Tomatillo | Mar 14 - Apr 23 | — | May 25 - Jun 13 | — | Plant in pairs for fruit set. |
| Tomato | Mar 14 - Apr 23 | — | May 25 - Jun 13 | — | Transplant only after frost risk passes; use Wall O' Water or row cover early. |
| Turnip | — | Jul 28 - Sep 7 | — | — | Roots and greens both improve after frost. |
| Winter Squash | — | May 25 - Jun 3 | — | — | Choose early types (e.g. acorn, buttercup); may also start indoors in May to gain time. |
| Zucchini | — | May 25 - Jun 3 | — | — | Direct-sow in warm soil; very productive in short seasons. |
Herbs
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Basil | Mar 25 - Apr 23 | — | Jun 4 - Jun 13 | — | Cold-sensitive; do not set out until nights stay above 50°F. |
| Cilantro / Coriander | — | Apr 14 - May 24 | — | — | Cool-season; bolts in heat, so sow early and succession. |
| Dill | — | Apr 24 - May 24 | — | — | Direct-sow after frost; self-seeds readily. |
| Parsley | Feb 22 - Apr 23 | — | — | — | Slow to germinate; start early or direct-sow late April. |
Fruits
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Ground Cherry | Mar 14 - Apr 23 | — | May 25 - Jun 13 | — | Sprawling; give room and harvest fallen husks. |
| Muskmelon / Cantaloupe | — | — | Jun 4 - Jun 13 | — | Marginal; start indoors May, transplant onto black plastic + tunnel. |
| Watermelon | — | — | Jun 4 - Jun 13 | — | Only short-season icebox types under plastic/tunnel will ripen. |
Flowers
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Borage | — | May 25 - Jun 3 | — | — | Direct-sow; attracts pollinators, self-seeds. |
| Calendula | — | Apr 14 - May 24 | — | — | Hardy annual; tolerates cool soil and light frost. |
| Cosmos | — | May 25 - Jun 3 | — | — | Easy from direct seed once frost has passed. |
| Marigold | — | — | May 25 - Jun 13 | — | Plant after frost; good pest companion. |
| Nasturtium | — | May 25 - Jun 3 | — | — | Direct-sow after frost; edible flowers and leaves. |
| Snapdragon | Feb 22 - Apr 23 | — | — | — | Cold-hardy; transplant early and it shrugs off light frost. |
| Sunflower | — | May 14 - Jun 23 | — | — | Direct-sow; choose shorter-season varieties for seed. |
| Sweet Pea | — | Apr 14 - May 24 | — | — | Sow early in cool soil; provide support. |
| Zinnia | — | — | May 25 - Jun 13 | — | Frost-tender; start indoors or transplant after last frost. |
Zone 3a vs Zone 3b
USDA divides zone 3 into two half-zones 5°F apart. Zone 3b is the warmer one; here is how its frost dates compare with zone 3a and the zone 3 average.
| Zone 3a | Zone 3 | Zone 3b | |
|---|---|---|---|
| Winter low | −40 to −35°F | −40 to −30°F | −35 to −30°F |
| Last spring frost | Jun 1 | May 25 | May 18 |
| First fall frost | Sep 5 | Sep 12 | Sep 19 |
| Growing season | 91 days | 105 days | 119 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 3b Growing Tips
- ✓ Start long-season heat-lovers (onions, leeks, celery, peppers, eggplant) indoors under grow lights 8-12 weeks before the late-May last frost; buying transplants is otherwise the only way to get a crop.
- ✓ Always choose the earliest, shortest-season cultivars (look for sub-65-day tomatoes, 70-85 day corn, and acorn/buttercup squash) — full-season varieties will not ripen before the September frost.
- ✓ Use season-extension aggressively: black plastic mulch, row cover, low tunnels, cloches, and Wall O' Water devices add the heat units that marginal crops (melons, peppers, eggplant) need.
- ✓ Plant garlic in late September/October and mulch heavily (6-8 inches of straw) so it overwinters under snow for a July harvest the next year.
- ✓ Lean into cold-hardy crops that thrive here — kale, Brussels sprouts, carrots, parsnips, cabbage, and mâche actually improve in flavor after frost and define the productive fall garden.
- ✓ Watch microclimates and protect against frost into early June and again from late August onward — keep row cover on hand all season, since killing frosts can bookend the short summer.
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Sign Up FreeFrequently Asked Questions
What can I plant in spring in zone 3b?
In zone 3b, spring planting includes Onion (Bulb), Leek, Celery, Celeriac, Pepper (Bell & Hot), Eggplant, Tomato, Tomatillo, and more. See the spring section above for each crop's timing.
What is the last frost date for zone 3b?
The average last spring frost date for USDA zone 3b is May 18. The first fall frost typically arrives around Sep 19, giving a growing season of approximately 119 days.
When is the first frost in zone 3b?
The average first fall frost in USDA zone 3b arrives around Sep 19. 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 3b?
In zone 3b, start crops like Onion (Bulb) indoors around Feb 14 - Mar 24. Check the seasonal sections above for each crop's indoor-sowing window.
What can I plant in fall in zone 3b?
Fall planting in zone 3b includes Garlic, Spinach, Lettuce, Arugula, Mizuna, Tatsoi, Bok Choy / Pak Choi, Mustard Greens, and more.
How long is the growing season in zone 3b?
Zone 3b has an average growing season of 119 days, from the last spring frost around May 18 to the first fall frost around Sep 19.
What is the difference between zone 3a and zone 3b?
Zone 3b is the warmer half of USDA zone 3, with average coldest winter nights of −35 to −30°F. Compared with the zone 3 averages (last frost May 25, first frost Sep 12), zone 3b's last spring frost is about a week earlier (May 18) and its first fall frost about a week later (Sep 19), so zone 3a gardeners plant about two weeks later in spring and earlier in fall than zone 3b.
What to plant right now
Month-specific guides for zone 3, 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