Zone 5 Planting Calendar

What to do

Vegetables sown outdoors go in one of four waves, timed in weeks off your last-frost date rather than a fixed day on the calendar. The table below works those weeks out at both ends of zone 5’s range as worked examples; count the Weeks column’s offset back or forward from your own date to get yours. Crops in the earlier waves generally go into the ground as seed; the tender and very tender waves are often set out as transplants started indoors weeks before, and starting seeds indoors covers that lead time.

Wave	Weeks vs. last frost	Early window (~Apr 8 last frost)	Late window (~May 30 last frost)	Crops
Hardy	2–4 weeks before	Mar 11–25	May 2–16	broccoli, cabbage, kale, kohlrabi, onions, lettuce, peas, radishes, spinach, turnips
Semi-hardy	0–2 weeks before	Mar 25–Apr 8	May 16–30	beets, carrots, cauliflower, parsley, parsnips, potatoes, Swiss chard
Tender	at last frost	Apr 8	May 30	bush beans and trellised pole beans, celery, corn, cucumbers, New Zealand spinach, summer squash
Very tender	2+ weeks after	from Apr 22	from Jun 13	lima beans, cantaloupe, eggplant, okra, peppers, pumpkin, sweet potatoes, tomatillos, winter squash, tomatoes, watermelon

Hardy crops keep growing at daytime temperatures as low as 40°F; semi-hardy crops need 40–50°F minimum daytime temperatures; very tender crops want above 60°F and do best between 70°F and 95°F. A week of daytime temperatures below 55°F can stunt a very tender crop even after its window opens — real risk toward the early end of zone 5, where an April planting date can still meet a cold snap. A longer-season tomato fits at zone 5’s early-window end — roughly 185 frost-free days derived from the windows above, against about 114 at the late end; the tomato guide covers the trade-off.

Soil temperature is the better check than any date on this table. Measure it around 8 a.m., 4 inches deep for most crops and 6 inches for beans, and plant once the soil holds a crop’s minimum at that reading. Two legitimate kinds of minimum show up in university-run gardening research: a germination floor, the temperature at which a seed will eventually sprout (peas at 40°F, corn and tomato around 50°F, beans and warm-season vine crops around 55–60°F), versus a recommendation for prompt growth in a cooler climate, which runs higher for the same crops — tomato around 70°F, beans around 72°F. Use the germination floor for “will this even come up,” and the higher figure if you want strong growth rather than a slow struggle. Vine crops such as cucumbers, squash, and melons resent root disturbance and do best direct-seeded; started as transplants, keep them to 2–3 weeks from seeding before they go in the ground.

Running four offsets against two frost dates for a dozen crops is the tedious part. Arbor asks for your zip code when you set up a garden, resolves your zone and pulls that zone’s average frost dates, and counts each crop’s planting week back from them using that crop’s own offset — then adds the resulting tasks to your list when you confirm the plan. Those per-crop offsets sometimes differ by a week or two from the hardiness-tier windows above, and the app schedules potatoes two weeks after last frost rather than before it.

Zone and season notes

The zone’s national window is wider than most: one region’s last-frost date can run a month or more ahead of another’s even though both carry the zone 5 label. That’s a real, sourced spread rather than something to average away — a USDA zone number measures winter cold, not spring frost timing, and it’s the reason “zone 5 means plant on this date” doesn’t hold up. Treat the window above as a starting point and replace it with your own observed date.

Within a state, region can matter as much as the zone label. Illinois’s own three regions run from an early-April median last frost in the south to late-April in the north, with growing seasons from 215 days in the far south down to 180 in the far north. Southern Illinois starts about two weeks ahead of central Illinois and harvests about two weeks longer, and northern Illinois plants about two weeks later than central — roughly a month end to end inside one state. The 5a/5b half-zone split adds to that. In the same area, 5a plants later than 5b, since 5a is the colder-winter half. Ohio State’s calendar is built on zone 6a and tells 5b gardeners to push spring dates one week later. In 5a, push that adjusted date back further still, or better, work from your own zip-code lookup.

Fall is a second full season here, not an afterthought. Cool-season crops tolerate light frost and keep growing until a hard freeze, and fall plantings are timed backward from your first-frost date using each variety’s days-to-maturity figure from the seed packet — some fall crops can go in as early as July. Once a bed is finished for the year, a cover crop can go in through September or October. Hardneck garlic suits zone 5, and it holds a bed from mid-September or October right through until July. For the frost-date math itself, see when to plant vegetables.