Pennsylvania · zones 5b–7b
When to plant broccoli in Pennsylvania.
Sow or transplant between Mar 4 to Apr 1 in a typical year, keyed to Pennsylvania's median last frost around Apr 25. A second, fall sowing fits Jun 30 to Aug 9. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Broccoli dates for a typical Pennsylvania 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
Jun 30 to Aug 9
Counted back from the ~Oct 14 first frost.
Harvest
~60 days later
~1.2 lb per plant over ~3 weeks.
Pennsylvania spans more than one climate: Zone 6 is the most common zone, but the state runs 5b to 7b. 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.
Pennsylvania growing notes
Broccoli runs on two different clocks across Pennsylvania.
A full zone separates the plateau from the southeast corner
Pennsylvania's hardiness zones stretch from the colder end across the northern tier and the Allegheny plateau up to the milder end in the far southeastern corner near Philadelphia, and that spread changes which of broccoli's two windows deserves the better bed. A late cold snap hitting young transplants before heads ever start forming can button the plant, locking growth at a head no bigger than a golf ball, and nothing that happens afterward gets it moving again.
Plateau gardens simply run more risk of catching that kind of cold snap during the spring window than gardens in the milder southeast corner do. That tips the balance toward treating the fall crop as the season's main event on the plateau: a transplant set for fall grows through the warmth of late summer and finishes as nights cool, which firms up a head rather than shocking it. Southeastern growers, working milder spring nights, can treat both windows as close enough to equal and let bed space decide.
Ridge-and-valley soil swings from sour to sweet within a few miles
Much of Pennsylvania's ridge-and-valley country sits over naturally acidic ground derived from sandstone and shale, and broccoli stalls hard on soil that reads sour, showing stunted, purplish growth that looks like a feeding problem but is really an acidity problem locking up nutrients that are already present. Lime worked in based on an actual soil test, not a guess, is the fix, and it needs months to shift the ground, so test well ahead of a spring planting rather than the week transplants go in.
Where the ground runs closer to neutral, especially over Pennsylvania's limestone valleys, broccoli skips that stall entirely, but the crop still wants 2 inches of compost worked into the bed ahead of transplanting, and it wants the row held at full spacing rather than squeezed tighter to fit more plants, since a shoulder-to-shoulder row shades its own lower leaves and slows the whole planting down. Broccoli crowded past that spacing comes up small and loose regardless of which rock the garden happens to sit over.
Scouting three separate pests instead of spraying on a calendar
Flea beetles do their worst damage in the first weeks after transplants go in, shot-holing young leaves before the plant has spare leaf area to lose, and row cover kept over the bed from the day transplants go in right up until heads start forming shuts them out entirely, no spray required. Cabbage worms and loopers follow through summer and fall, leaving ragged holes and dark droppings on the underside; a weekly check of 10 plants, reaching for Bt once caterpillars are turning up on more than about one plant in ten with heads already forming, keeps a spray from going out in a light year. Before heads form the plant tolerates far more damage than that, so the same count that justifies treating in August is not worth acting on in June.
Aphids are the one pest on this list that gets into the part you actually eat rather than just chewing the leaves around it, clustering down inside the forming head where a spray cannot reach cleanly. Rinse the colony loose with a strong stream of water pointed straight up into the underside of the head a day or two before you plan to cut it; the curd stays intact and the crop stays free of anything a market grower would need to wash off twice.
In Pennsylvania: watch for
The pests that find broccoli here.
A middle-length season, about 172 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: Pennsylvania gives broccoli about 172 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 Pennsylvania: questions
When should I plant broccoli in Pennsylvania?+
In a typical Pennsylvania 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: Jun 30 to Aug 9. Your exact dates shift with your ZIP code and microclimate.
When do I start broccoli seeds indoors in Pennsylvania?+
Start seeds inside about 6 weeks before set-out: roughly Jan 21 to Feb 18 for a typical Pennsylvania season.
What USDA zone is Pennsylvania?+
Pennsylvania spans zones 5b–7b, 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.