Ohio · zones 5b–6b
When to plant kale in Ohio.
Sow or transplant between Mar 18 to Apr 15 in a typical year, keyed to Ohio's median last frost around Apr 25. A second, fall sowing fits Jul 15 to Aug 30. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Kale dates for a typical Ohio season.
1 · Start indoors
Feb 4 to Mar 4
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Mar 18 to Apr 15
Keyed to the ~Apr 25 last frost. Sow 0.25" deep, 16" apart.
Fall round
Jul 15 to Aug 30
Counted back from the ~Oct 15 first frost.
Harvest
~45 days later
~2 lb per plant over ~16 weeks.
Ohio spans more than one climate: Zone 6 is the most common zone, but the state runs 5b to 6b. That's why the planner works from your ZIP code's frost dates, not your zone: mountain and coastal gardens in the same state can be three weeks apart.
Ohio growing notes
Kale is the one crop Ohio's clay does not scare.
Working with, not against, glacial clay
The clay-heavy glacial till common across northeastern Ohio, the ground left behind when the last ice sheet retreated and dropped everything it was carrying, frustrates most vegetables but barely slows kale down. The crop's roots tolerate heavier ground than tomatoes or carrots ever will, so gardeners on clay can skip the elaborate raised-bed program other crops demand and simply work in 2 inches of compost each fall.
The one clay problem kale cannot shrug off is standing water in early spring, when a saturated bed can rot young transplants before they establish. A quick test: dig a 12-inch hole after a rain and time how long it takes to drain. Longer than 4 hours and the bed needs a slight crown or a few added inches of compost worked through the top layer before kale goes in.
Cold makes it better, not worse
Kale is one of the few crops where an Ohio cold snap improves the harvest instead of ending it. Leaves exposed to temperatures in the low 30s convert stored starches into sugars as a natural antifreeze, which is why a kale leaf picked after a frost tastes noticeably sweeter and less bitter than the same leaf picked in late summer heat.
Established plants tolerate nights into the low 20s without protection and can survive briefly into the teens under a single layer of row cover, which means an Ohio kale bed often keeps producing weeks after the rest of the garden has gone dormant. The test for how much longer to keep picking: as long as the center growth point stays green and firm, new leaves keep coming.
Aphids hide where you are not looking
Kale aphids rarely sit in plain sight on a leaf's top surface; they cluster in the tight curl where a new leaf meets the stem, protected from both rain and a casual glance. A plant that looks clean from a few feet away can be carrying a colony that has already curled and yellowed the newest growth by the time you notice.
A hard spray of water aimed directly into those crevices, repeated every 2 or 3 days for a week, knocks the colony down without reaching for a spray bottle. Flea beetles are the other early-season risk, riddling young leaves with small holes; row cover laid at transplant time keeps both pests off the plant during the stretch it is most vulnerable.
In Ohio: watch for
The pests that find kale here.
A middle-length season, about 173 frost-free days, means kale overlaps cabbage worms & loopers for a stretch each summer. Check plants every week or two and treat early.
Green caterpillars chewing ragged holes; green droppings.
Organic fix: Handpick, cover with netting, spray Bt.
Gray-green clusters tucked into the leaf folds.
Organic fix: Blast with water, then insecticidal soap.
Tiny holes peppering the young leaves.
Organic fix: Row cover from day one; diatomaceous earth.
Black rot
Yellow V-shaped wedges cutting in from the leaf edge, veins blackening inside.
Organic fix: Pull infected plants, water at the base, keep brassicas out of that bed 3 years.
Seedlings wilt, yellow and stall for no reason; white maggots tunnel the roots.
Organic fix: Row cover before the flies are up, when yellow rocket blooms; rotate the bed.
Your season math: Ohio gives kale about 173 frost-free days, and it needs roughly 45 days to a first harvest. It's a one-planting crop, so time that single sowing well.
Planting kale in Ohio: questions
When should I plant kale in Ohio?+
In a typical Ohio year, sow kale or set out transplants between Mar 18 to Apr 15, keyed to the state's median last frost around Apr 25. There's also a fall window: Jul 15 to Aug 30. Your exact dates shift with your ZIP code and microclimate.
When do I start kale seeds indoors in Ohio?+
Start seeds inside about 6 weeks before set-out: roughly Feb 4 to Mar 4 for a typical Ohio season.
What USDA zone is Ohio?+
Ohio spans zones 5b–6b, mostly zone 6. But frost dates, not zones, set planting time. The free planner uses your ZIP code's actual frost dates.
How many kale plants do I need?+
Depends who you're feeding. The crop page has exact counts per household size, or the free planner does the math for your family in about 60 seconds.