Ohio · zones 5b–6b
When to plant broccoli in Ohio.
Sow or transplant between Mar 4 to Apr 1 in a typical year, keyed to Ohio's median last frost around Apr 25. A second, fall sowing fits Jul 1 to Aug 10. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Broccoli dates for a typical Ohio season.
1 · Start indoors
Jan 21 to Feb 18
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Mar 4 to Apr 1
Keyed to the ~Apr 25 last frost. Sow 0.5" deep, 18" apart.
Fall round
Jul 1 to Aug 10
Counted back from the ~Oct 15 first frost.
Harvest
~60 days later
~1.2 lb per plant over ~3 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
Near Lake Erie, broccoli runs on the lake's clock.
The lake slows spring and stretches fall
Broccoli wants steady cool weather between about 40 and 70 degrees to form a tight head, and Ohio counties within a few miles of Lake Erie get a strange gift for that: the lake stays cold well into late spring, holding shoreline air temperatures down and delaying the jump into 80-degree afternoons that ruins a spring broccoli crop farther inland. The tradeoff is that shoreline planting runs later than gardeners 30 miles south expect.
That same lake effect works in broccoli's favor once autumn arrives. Water that stored summer heat all season releases it slowly through the fall, buffering shoreline counties against the first hard freeze that shuts down broccoli farther south in the state. A fall crop planted near the lake routinely holds quality 2 to 3 weeks longer than the same variety grown on the inland till plains.
Lean on the fall window and pick varieties for it
Given that lake-effect stretch, Ohio broccoli rewards growers who treat fall as the main event rather than a backup to spring. Belstar produces a large central head with a strong follow-up of side shoots, which matters because those side shoots are most of the harvest once the main head is cut. Waltham 29, bred specifically for cold tolerance, holds up on its own into the upper 20s; a single layer of row cover only buys 4 to 6 more degrees, not enough by itself to guarantee a firm head once true low-20s cold settles in.
Direct-seed nothing here; broccoli started from transplant gets a 5-to-6-week jump that a direct-sown plant never makes up before the lake's warm window closes. Set out transplants at 4 or 5 true leaves and no later, because it is the older, root-bound transplant left too long in its tray, not the young one, that runs the real risk of premature buttoning, forming a tiny head the size of a coin and quitting growth for good.
Flea beetles first, then the caterpillar crew
Flea beetles hit broccoli transplants hardest in the first 2 weeks after they go in the ground, riddling leaves with a shot-hole pattern of tiny holes. Count the holes on a young leaf: fewer than 10 rarely slows a plant down, but a leaf that is more hole than tissue means the transplant needs row cover before it loses too much surface area to recover.
By midsummer the threat shifts to cabbage worms and loopers, both of which start as a single white or gray moth laying eggs on leaf undersides. Check 5 leaves per plant weekly for the pale yellow egg clusters, and treat with Bt as soon as damage appears rather than waiting for a head to form, because a caterpillar working inside a forming head is nearly impossible to rinse out later.
In Ohio: watch for
The pests that find broccoli here.
A middle-length season, about 173 frost-free days, means broccoli 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 broccoli about 173 frost-free days, and it needs roughly 60 days to a first harvest. It's a one-planting crop, so time that single sowing well.
Planting broccoli in Ohio: questions
When should I plant broccoli in Ohio?+
In a typical Ohio year, sow broccoli or set out transplants between Mar 4 to Apr 1, keyed to the state's median last frost around Apr 25. There's also a fall window: Jul 1 to Aug 10. Your exact dates shift with your ZIP code and microclimate.
When do I start broccoli seeds indoors in Ohio?+
Start seeds inside about 6 weeks before set-out: roughly Jan 21 to Feb 18 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 broccoli 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.