Arbor

Zone 4 Planting Calendar

Updated August 2026

Zone 4’s last frost typically falls somewhere between about May 11 and May 29, and the first fall frost between about September 24 and September 30. Only zone 3 runs a shorter season in this series. A USDA hardiness zone is built from a 30-year average of winter’s extreme minimum cold, not from frost dates or season length, so the zone number alone won’t tell you when to plant. Find your own last-frost date before you use any date below: the National Weather Service publishes average freeze dates station by station on weather.gov. For the frost-date math itself, see when to plant vegetables.

A season this short changes the planning. Every week saved by starting a crop indoors instead of direct-seeding it is a week added to the growing side, and the days-to-maturity number on a seed packet matters more here than in a longer zone — an 85-day tomato variety and a 60-day one are two different bets in a zone whose weather stations run from about 118 frost-free days to 141. Growing tomatoes covers how to weigh that trade-off by variety, and the same math decides whether winter squash and melons finish at all in the late window; check their guides’ variety notes first. Vine crops are the exception to that transplant-first logic: cucumbers, squash, and melons resent root disturbance and do best direct-seeded once the soil is warm enough. If you do start them indoors, set them out no more than 2–3 weeks from seeding.

Zone 4 · Frost & planting windows

JanFebMarAprMayJunJulAugSepOctNovDec
Zone 4: last frost typically May 11–May 29, first frost typically Sep 24–Sep 30. Plant hardy and semi-hardy crops before last frost (Apr 13–May 29); tender and very tender crops from last frost onward (May 11–Jun 12). Find your own frost dates — the zone is a window, not a single day.

What to do

Vegetables sown outdoors go in one of four waves, timed in weeks off your last-frost date, not a fixed calendar day. The table works those weeks out at both ends of zone 4’s range — find the column closer to your own last-frost date and read down it, or, if your date lands mid-range, count each wave’s offset off your own date.

Wave Weeks vs. last frost Early window (~May 11 last frost) Late window (~May 29 last frost) Crops
Hardy 2–4 weeks before Apr 13–27 May 1–15 broccoli, cabbage, kale, kohlrabi, onions, lettuce, peas, radishes, spinach, turnips
Semi-hardy 0–2 weeks before Apr 27–May 11 May 15–29 beets, carrots, cauliflower, parsley, parsnips, potatoes, Swiss chard
Tender at last frost May 11 May 29 bush beans and trellised pole beans, celery, corn, cucumbers, summer squash
Very tender 2+ weeks after from May 25 from Jun 12 lima beans, cantaloupe, eggplant, okra, peppers, pumpkin, sweet potatoes, tomatillos, winter squash, tomatoes, watermelon

Those are outdoor dates, sown in the bed or set out as transplants started weeks earlier. A common seed-packet convention is to start trays 4 to 6 weeks before your last-frost date, with tomatoes at the long end of that and peppers closer to 8. Hardy crops keep growing at daytime temperatures as low as 40°F; very tender crops want above 60°F and prefer 70–95°F, and a week of daytime temperatures below 55°F can stunt one even after its window opens — a real risk in a zone 4 spring.

Soil temperature is a better check than any date on this table: the last-frost date tracks air temperature, germination tracks soil temperature, and the two don’t move together in a variable spring. Measure at 8 a.m., 4 inches deep (6 inches for beans), and plant once the soil holds a crop’s minimum: 40 to 50°F for cool-season crops, 55 to 60°F for moderately warm-season ones, 65°F or better for heat lovers. Reported minimums vary widely depending on whether a guide means the coldest soil a seed will germinate in, or the temperature it recommends waiting for. Treat any single number as a floor, not a target. Lettuce and onions germinate as cold as 35°F but come up stronger well above that; corn, tomatoes, and cucumbers are worth waiting on either way.

Running four offsets against two frost dates is the tedious part. Arbor asks for your zip code when you set up a garden, resolves your zone, pulls that zone’s average frost dates, and counts each crop’s planting week back from them using its own offset — then adds the tasks to your list when you confirm the plan. Those offsets don’t always match the waves above, which group crops by cold hardiness rather than by sowing date: beans, corn, cucumbers, and squash get held two weeks past last frost, the safer call in this zone.

Zone and season notes

Zone 4 spans northern New England, the Great Lakes states, the northern Great Plains, and higher-elevation pockets of the Rockies. Even inside that band the spread is real. Stations across Minnesota, North Dakota, and northern Wisconsin run two and a half weeks apart in spring last frost and about a week apart in fall, among places sharing one winter low. Your own station-level number beats a zone-wide average every time. Colder pockets nearby run short enough to behave like zone 3, because lake proximity, elevation, and latitude shift a real season by weeks inside one named zone.

Fall is the second season here, and with frost by late September it starts earlier than a longer zone’s. Count a crop’s days to maturity back from your first-frost date to find its last safe sowing date. Hardy crops can go in later than that: spinach and turnips tolerate light frost and keep growing past it. Beans and squash need every day of that count. With those same stations working out to 118 to 141 frost-free days apiece, count your own from your own two dates: a short-season variety and a head start indoors both do real work toward closing that gap. A row cover (light fabric or perforated plastic laid over the plants) raises daytime air temperature under it by up to 10°F at either end of the season. If your own observed frost dates fall outside the window above, trust your dates over the zone.

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