New Hampshire · zones 4b–6a
When to plant kale in New Hampshire.
Sow or transplant between Apr 7 to May 5 in a typical year, keyed to New Hampshire's median last frost around May 15. A second, fall sowing fits Jun 28 to Aug 13. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Kale dates for a typical New Hampshire season.
1 · Start indoors
Feb 24 to Mar 24
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Apr 7 to May 5
Keyed to the ~May 15 last frost. Sow 0.25" deep, 16" apart.
Fall round
Jun 28 to Aug 13
Counted back from the ~Sep 28 first frost.
Harvest
~45 days later
~2 lb per plant over ~16 weeks.
New Hampshire spans more than one climate: Zone 5 is the most common zone, but the state runs 4b to 6a. 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.
In New Hampshire: watch for
The pests that find kale here.
The short season here, about 136 frost-free days, keeps kale in front of cabbage worms & loopers only briefly. One early row cover usually carries a planting through the worst of it.
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: New Hampshire gives kale about 136 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 New Hampshire: questions
When should I plant kale in New Hampshire?+
In a typical New Hampshire year, sow kale or set out transplants between Apr 7 to May 5, keyed to the state's median last frost around May 15. There's also a fall window: Jun 28 to Aug 13. Your exact dates shift with your ZIP code and microclimate.
When do I start kale seeds indoors in New Hampshire?+
Start seeds inside about 6 weeks before set-out: roughly Feb 24 to Mar 24 for a typical New Hampshire season.
What USDA zone is New Hampshire?+
New Hampshire spans zones 4b–6a, mostly zone 5. 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.