Brought to you by garden.gg Zone 3a 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 3a is the cooler half of USDA zone 3, where the average coldest winter night bottoms out at −40 to −35°F. Compared with the zone 3 averages, the last spring frost in zone 3a comes about a week later (Jun 1) and the first fall frost about a week earlier (Sep 5), for a growing season of about 91 days. Every planting window on this page is shifted to match: spring sowing and transplant dates move a week later, fall plantings a week earlier. 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 3a garden — free
What to Plant in Zone 3a This Fall (September–November)
The average first fall frost in zone 3a is Sep 5. 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 3a's frost date, that gives these plant-by dates:
Plant by Jul 23
30 days to maturity + 14-day fall factor
Plant by Jul 13
40 days to maturity + 14-day fall factor
Plant by Jul 8
45 days to maturity + 14-day fall factor
Plant by Jul 3
50 days to maturity + 14-day fall factor
Zone 3a and 3b: these dates count back from zone 3a's first frost, which is about a week earlier than the zone 3 average of Sep 12. Zone 3b gardeners have about two weeks more fall time — see the zone 3b fall dates.
Fall crops on this zone 3a 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 3a
The right crops and methods for each season, based on zone 3a'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 28 - Apr 7
Long-day varieties only; start 10-12 weeks before last frost, transplant mid-May.
Feb 28 - Apr 7
Slow to size up; needs the longest possible season.
Mar 8 - Apr 7
Start 10-12 weeks early; transplant after frost danger passes.
Mar 8 - Apr 7
Long-season root; start indoors with celery.
Mar 8 - Apr 17
Start 8-10 weeks before last frost; choose early, short-season varieties.
Mar 8 - Apr 17
Needs bottom heat; pick the earliest cultivars for zone 3.
Mar 28 - May 7
Start 6-8 weeks early; favor early determinate/short-season types (e.g. 55-65 day).
Mar 28 - May 7
Start with tomatoes; plant at least two for pollination.
Mar 28 - May 7
Treat like tomatillo; reliable in short seasons once established.
Mar 28 - May 7
Start indoors, transplant early May; tolerates light frost.
Mar 28 - May 7
Start indoors; keep growth steady to avoid buttoning.
Mar 28 - May 7
Hardy transplant; set out early-to-mid May.
Mar 28 - May 7
Long-season; start early so sprouts size up before hard fall frost.
Apr 8 - May 7
Can also be direct-sown; transplants give an earlier crop.
Apr 8 - May 7
Transplant after frost to reduce bolting risk.
Apr 8 - May 7
Very frost-tender; hold indoors until soil and nights warm (June).
Mar 8 - May 7
Slow to germinate; start early or direct-sow late April.
Mar 8 - May 7
Cold-hardy; transplant early and it shrugs off light frost.
Apr 28 - May 17
Sow as soon as soil is workable; tolerates frost.
Apr 28 - May 17
Very cold-tolerant; one of the earliest sowings.
Apr 28 - May 17
Likes cool weather; sow early before heat.
Apr 28 - Jun 7
Sow early; bolts fast once days lengthen and warm.
Apr 28 - Jun 7
Succession-sow every 2 weeks; very frost-tolerant.
Apr 28 - Jun 7
Fast cool-season green; bolts in summer heat.
Apr 28 - Jun 7
Quick, cold-hardy; sow as soon as soil works.
Apr 28 - Jun 7
Matures in 3-4 weeks; ideal early crop.
May 8 - May 27
Sow once soil reaches ~45°F; keep seedbed moist.
May 8 - May 27
Cold-tolerant; greens and roots both usable.
Apr 28 - Jun 7
Fast cool-season root; sow early.
May 8 - May 27
Slow germinator; needs full season, sweetens after frost.
Apr 28 - Jun 7
Extremely cold-hardy; direct-sow or transplant.
May 8 - May 17
Sow after worst frosts; productive all season.
May 8 - May 27
Plant seed potatoes 2-3 weeks before last frost; hill against late frost.
Apr 28 - Jun 7
Plant sets in early spring for summer harvest.
Apr 28 - Jun 7
Quick and cold-tolerant; succession-sow.
Apr 28 - Jun 7
Cool-season; bolts in heat, so sow early and succession.
May 8 - Jun 7
Direct-sow after frost; self-seeds readily.
Apr 28 - Jun 7
Hardy annual; tolerates cool soil and light frost.
Apr 28 - Jun 7
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.
Jun 8 - Jun 27
Transplant only after frost risk passes; use Wall O' Water or row cover early.
Jun 8 - Jun 27
Wait for warm nights (>50°F); black mulch boosts soil heat.
Jun 18 - Jun 27
Most heat-demanding nightshade; cloche or low tunnel helps.
Jun 8 - Jun 27
Plant in pairs for fruit set.
Jun 8 - Jun 27
Sprawling; give room and harvest fallen husks.
Jun 18 - Jun 27
Cold-sensitive; do not set out until nights stay above 50°F.
Jun 8 - Jun 17
Direct-sow in warm soil; very productive in short seasons.
Jun 8 - Jun 17
Fast-maturing; sow after frost on warm soil.
Jun 8 - Jun 17
Choose early types (e.g. acorn, buttercup); may also start indoors in May to gain time.
Jun 8 - Jun 17
Pick short-season varieties; start indoors late May for larger types.
Jun 8 - Jun 17
Short-season pie pumpkins ripen reliably; cure before storage.
Jun 8 - Jun 27
Warm soil only; row cover speeds early growth.
Jun 8 - Jun 17
Choose early/short-season hybrids; sow in blocks for pollination.
Jun 8 - Jun 27
Frost-tender; sow once soil warms; quick to harvest.
Jun 8 - Jun 27
Sow on warm soil with a trellis.
Jun 8 - Jun 27
Pick early-maturing edamame varieties for zone 3.
Jun 8 - Jun 27
Handles cool nights better than common beans; ornamental too.
Jun 18 - Jun 27
Marginal; start indoors May, transplant onto black plastic + tunnel.
Jun 18 - Jun 27
Only short-season icebox types under plastic/tunnel will ripen.
Jun 8 - Jun 27
Heat-loving green; sow after soil warms.
May 28 - Jul 7
Direct-sow; choose shorter-season varieties for seed.
Jun 8 - Jun 27
Frost-tender; start indoors or transplant after last frost.
Jun 8 - Jun 27
Plant after frost; good pest companion.
Jun 8 - Jun 17
Easy from direct seed once frost has passed.
Jun 8 - Jun 17
Direct-sow after frost; edible flowers and leaves.
Jun 8 - Jun 17
Direct-sow; attracts pollinators, self-seeds.
Jun 8 - Aug 7
Succession-sow heat-tolerant types in part shade through summer.
Jun 8 - Jul 7
Second sowing for fall storage.
Jun 8 - Jul 7
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 14 - Oct 24
Plant cloves 4-6 weeks before ground freezes; mulch heavily for winter.
Jul 14 - Aug 24
Fall sowing; very frost-hardy and can overwinter under mulch.
Jul 14 - Aug 24
Cool-weather flush; cover during early frosts to extend.
Jul 25 - Aug 24
Fast fall green; flavor improves in cool weather.
Jul 25 - Aug 24
Cold-hardy mustard for fall salads.
Jul 25 - Aug 24
Very cold-tolerant rosette green for fall.
Jul 25 - Aug 24
Fall sowing avoids spring bolting; protect from early frost.
Jul 25 - Aug 24
Quick fall crop; sweeter after light frost.
Jul 25 - Sep 3
Fast fall crop; tolerates frost.
Jul 14 - Aug 24
Roots and greens both improve after frost.
Jul 25 - Sep 23
Extremely cold-hardy; can overwinter under snow.
Jul 25 - Sep 23
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 28 - Mar 7
Begin long-day onion seedlings indoors under lights for a May transplant.
Feb 28 - Mar 7
Start indoors with onions; needs the longest lead time.
Feb 28 - Mar 7
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 3a.
Vegetables
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Amaranth (Leaf) | — | Jun 8 - Jun 27 | — | — | Heat-loving green; sow after soil warms. |
| Arugula | — | Apr 28 - Jun 7 | — | — | Fast fall green; flavor improves in cool weather. |
| Beet | — | Jun 8 - Jul 7 | — | Aug 25 - Oct 24 | Cold-tolerant; greens and roots both usable. |
| Bok Choy / Pak Choi | — | Jul 25 - Aug 24 | — | — | Fall sowing avoids spring bolting; protect from early frost. |
| Broccoli | Mar 28 - May 7 | — | — | — | Start indoors, transplant early May; tolerates light frost. |
| Brussels Sprouts | Mar 28 - May 7 | — | — | Aug 25 - Oct 24 | Long-season; start early so sprouts size up before hard fall frost. |
| Bush Bean | — | Jun 8 - Jun 27 | — | — | Frost-tender; sow once soil warms; quick to harvest. |
| Cabbage | Mar 28 - May 7 | — | — | Aug 25 - Oct 24 | Hardy transplant; set out early-to-mid May. |
| Carrot | — | Jun 8 - Jul 7 | — | Aug 25 - Oct 24 | Sow once soil reaches ~45°F; keep seedbed moist. |
| Cauliflower | Mar 28 - May 7 | — | — | — | Start indoors; keep growth steady to avoid buttoning. |
| Celeriac | Mar 8 - Apr 7 | — | — | — | Long-season root; start indoors with celery. |
| Celery | Mar 8 - Apr 7 | — | — | — | Start 10-12 weeks early; transplant after frost danger passes. |
| Claytonia (Miner's Lettuce) | — | Jul 25 - Sep 23 | — | — | Cold-hardy salad green; overwinters in cold frame. |
| Collards | — | — | — | Aug 25 - Oct 24 | — |
| Corn (Sweet) | — | Jun 8 - Jun 17 | — | — | Choose early/short-season hybrids; sow in blocks for pollination. |
| Cucumber | — | Jun 8 - Jun 27 | — | — | Warm soil only; row cover speeds early growth. |
| Edamame (Soybean) | — | Jun 8 - Jun 27 | — | — | Pick early-maturing edamame varieties for zone 3. |
| Eggplant | Mar 8 - Apr 17 | — | Jun 18 - Jun 27 | — | Most heat-demanding nightshade; cloche or low tunnel helps. |
| Fava Bean | — | Apr 28 - May 17 | — | — | Likes cool weather; sow early before heat. |
| Garden Pea | — | Apr 28 - May 17 | — | — | Sow as soon as soil is workable; tolerates frost. |
| Garlic | — | — | Sep 14 - Oct 24 | — | Plant cloves 4-6 weeks before ground freezes; mulch heavily for winter. |
| Husk-less / Pie Pumpkin | — | Jun 8 - Jun 17 | — | — | Short-season pie pumpkins ripen reliably; cure before storage. |
| Kale | — | Apr 28 - Jun 7 | — | Aug 25 - Oct 24 | Extremely cold-hardy; direct-sow or transplant. |
| Kohlrabi | Apr 8 - May 7 | — | — | — | Can also be direct-sown; transplants give an earlier crop. |
| Leek | Feb 28 - Apr 7 | — | — | Aug 25 - Oct 24 | Slow to size up; needs the longest possible season. |
| Lettuce | — | Jul 14 - Aug 24 | — | — | Cool-weather flush; cover during early frosts to extend. |
| Mizuna | — | Jul 25 - Aug 24 | — | — | Cold-hardy mustard for fall salads. |
| Mustard Greens | — | Apr 28 - Jun 7 | — | — | Quick fall crop; sweeter after light frost. |
| Napa Cabbage | Apr 8 - May 7 | — | — | — | Transplant after frost to reduce bolting risk. |
| Onion (Bulb) | Feb 28 - Apr 7 | — | — | Aug 25 - Sep 23 | Long-day varieties only; start 10-12 weeks before last frost, transplant mid-May. |
| Pac/Corn Salad (Mâche) | — | Jul 25 - Sep 23 | — | Nov 24 - Feb 21 | Extremely cold-hardy; can overwinter under snow. |
| Parsnip | — | May 8 - May 27 | — | — | Slow germinator; needs full season, sweetens after frost. |
| Pepper (Bell & Hot) | Mar 8 - Apr 17 | — | Jun 8 - Jun 27 | — | Wait for warm nights (>50°F); black mulch boosts soil heat. |
| Pole Bean | — | Jun 8 - Jun 27 | — | — | Sow on warm soil with a trellis. |
| Pole/Runner Bean (Scarlet) | — | Jun 8 - Jun 27 | — | — | Handles cool nights better than common beans; ornamental too. |
| Potato | — | — | May 8 - May 27 | Aug 25 - Sep 23 | Plant seed potatoes 2-3 weeks before last frost; hill against late frost. |
| Pumpkin | — | Jun 8 - Jun 17 | — | — | Pick short-season varieties; start indoors late May for larger types. |
| Radish | — | Apr 28 - Jun 7 | — | — | Fast fall crop; tolerates frost. |
| Rutabaga | — | — | — | Aug 25 - Oct 24 | — |
| Scallion / Green Onion | — | Apr 28 - Jun 7 | — | — | Quick and cold-tolerant; succession-sow. |
| Shallot | — | — | Apr 28 - Jun 7 | — | Plant sets in early spring for summer harvest. |
| Snap / Snow Pea | — | Apr 28 - May 17 | — | — | Very cold-tolerant; one of the earliest sowings. |
| Spinach | — | Jul 14 - Aug 24 | — | — | Fall sowing; very frost-hardy and can overwinter under mulch. |
| Summer Squash | — | Jun 8 - Jun 17 | — | — | Fast-maturing; sow after frost on warm soil. |
| Swiss Chard | — | May 8 - May 17 | — | — | Sow after worst frosts; productive all season. |
| Tatsoi | — | Jul 25 - Aug 24 | — | — | Very cold-tolerant rosette green for fall. |
| Tomatillo | Mar 28 - May 7 | — | Jun 8 - Jun 27 | — | Plant in pairs for fruit set. |
| Tomato | Mar 28 - May 7 | — | Jun 8 - Jun 27 | — | Transplant only after frost risk passes; use Wall O' Water or row cover early. |
| Turnip | — | Jul 14 - Aug 24 | — | — | Roots and greens both improve after frost. |
| Winter Squash | — | Jun 8 - Jun 17 | — | — | Choose early types (e.g. acorn, buttercup); may also start indoors in May to gain time. |
| Zucchini | — | Jun 8 - Jun 17 | — | — | Direct-sow in warm soil; very productive in short seasons. |
Herbs
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Basil | Apr 8 - May 7 | — | Jun 18 - Jun 27 | — | Cold-sensitive; do not set out until nights stay above 50°F. |
| Cilantro / Coriander | — | Apr 28 - Jun 7 | — | — | Cool-season; bolts in heat, so sow early and succession. |
| Dill | — | May 8 - Jun 7 | — | — | Direct-sow after frost; self-seeds readily. |
| Parsley | Mar 8 - May 7 | — | — | — | Slow to germinate; start early or direct-sow late April. |
Fruits
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Ground Cherry | Mar 28 - May 7 | — | Jun 8 - Jun 27 | — | Sprawling; give room and harvest fallen husks. |
| Muskmelon / Cantaloupe | — | — | Jun 18 - Jun 27 | — | Marginal; start indoors May, transplant onto black plastic + tunnel. |
| Watermelon | — | — | Jun 18 - Jun 27 | — | Only short-season icebox types under plastic/tunnel will ripen. |
Flowers
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Notes |
|---|---|---|---|---|---|
| Borage | — | Jun 8 - Jun 17 | — | — | Direct-sow; attracts pollinators, self-seeds. |
| Calendula | — | Apr 28 - Jun 7 | — | — | Hardy annual; tolerates cool soil and light frost. |
| Cosmos | — | Jun 8 - Jun 17 | — | — | Easy from direct seed once frost has passed. |
| Marigold | — | — | Jun 8 - Jun 27 | — | Plant after frost; good pest companion. |
| Nasturtium | — | Jun 8 - Jun 17 | — | — | Direct-sow after frost; edible flowers and leaves. |
| Snapdragon | Mar 8 - May 7 | — | — | — | Cold-hardy; transplant early and it shrugs off light frost. |
| Sunflower | — | May 28 - Jul 7 | — | — | Direct-sow; choose shorter-season varieties for seed. |
| Sweet Pea | — | Apr 28 - Jun 7 | — | — | Sow early in cool soil; provide support. |
| Zinnia | — | — | Jun 8 - Jun 27 | — | 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 3a is the cooler one; here is how its frost dates compare with zone 3b 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 3a 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 3a?
In zone 3a, 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 3a?
The average last spring frost date for USDA zone 3a is Jun 1. The first fall frost typically arrives around Sep 5, giving a growing season of approximately 91 days.
When is the first frost in zone 3a?
The average first fall frost in USDA zone 3a arrives around Sep 5. 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 3a?
In zone 3a, start crops like Onion (Bulb) indoors around Feb 28 - Apr 7. Check the seasonal sections above for each crop's indoor-sowing window.
What can I plant in fall in zone 3a?
Fall planting in zone 3a includes Garlic, Spinach, Lettuce, Arugula, Mizuna, Tatsoi, Bok Choy / Pak Choi, Mustard Greens, and more.
How long is the growing season in zone 3a?
Zone 3a has an average growing season of 91 days, from the last spring frost around Jun 1 to the first fall frost around Sep 5.
What is the difference between zone 3a and zone 3b?
Zone 3a is the cooler half of USDA zone 3, with average coldest winter nights of −40 to −35°F. Compared with the zone 3 averages (last frost May 25, first frost Sep 12), zone 3a's last spring frost is about a week later (Jun 1) and its first fall frost about a week earlier (Sep 5), so zone 3b gardeners plant about two weeks earlier in spring and later in fall than zone 3a.
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