New Hampshire planting calendar

When to plant garlic in New Hampshire — sow, transplant & harvest dates

New Hampshire is mostly USDA zone 5b (range 3b-6a). Dates below are derived from garlic's frost tolerance and New Hampshire's frost window — not generic national averages.

Garlic planting timetable for New Hampshire

Stage	When in New Hampshire	Anchor
Plant cloves outdoors	mid-August — late August (August 21)	~35 days before New Hampshire's first fall frost (late September)
First harvest	late April the following year	~240 days from autumn planting

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why New Hampshire's climate shifts the garlic dates

New Hampshire's first fall frost averages late September, which sets the autumn planting clock — cloves need 4-6 weeks of root growth before the ground freezes. New Hampshire is a cold New England state with a brief but reliable summer, milder along the small seacoast and colder in the mountains.

Garlic is the unusual one — plant cloves in autumn (4-6 weeks before the first hard fall frost) so they put down roots before winter, then break dormancy in spring and bulb up over the long days of early summer. Cold-winter zones grow hardneck varieties; mild-winter zones do better with softneck.

Frost-risk note

Get cloves in before the ground freezes solid; in the White Mountains and far north (zone 3b) mulch heavily with 10-15 cm of straw to stop freeze-thaw heaving.

Regional variation within New Hampshire

the White Mountains and far north (zone 3b) should plant at the earlier end of the window and grow hardneck types; the short Atlantic seacoast near Portsmouth (zone 6a) can plant later and lean on softneck varieties.

Manchester — USDA zone 5b
Concord — USDA zone 5b
Nashua — USDA zone 5b
Portsmouth — USDA zone 6a

What else to plant in New Hampshire around then

The same autumn slot suits overwintering onions, shallots, and a final sowing of spinach or mache.

Quick-grow guide

Sun: Full sun — 6+ hours direct.
Soil temperature for germination: Soil 10-15 °C (50-60 °F) at planting.
Spacing: 4-6 inches (10-15 cm) between plants.
Days to harvest: ~240 days from autumn planting.

Frequently asked questions

When is the best time to plant garlic in New Hampshire?

In New Hampshire (mostly USDA zone 5b), plant garlic cloves outdoors around mid-August — late August — roughly 35 days before the first fall frost (late September). Cloves root through autumn, overwinter, then bulb up by late April next year. Garlic is fall-planted — cloves need winter chilling, so they go in the ground in autumn, root before the freeze, and bulb up the following summer.

What USDA zone is New Hampshire?

Most of New Hampshire sits in USDA hardiness zone 5b, with the state spanning roughly 3b-6a from the White Mountains and far north (zone 3b) to the short Atlantic seacoast near Portsmouth (zone 6a). The last spring frost averages mid-May and the first fall frost late September.

Can you grow garlic in New Hampshire?

Yes. New Hampshire's dominant zone 5b supports garlic — the key is timing. Garlic is fall-planted — cloves need winter chilling, so they go in the ground in autumn, root before the freeze, and bulb up the following summer.

Does the planting date change across New Hampshire?

What else can I plant in New Hampshire around the same time?

The same autumn slot suits overwintering onions, shallots, and a final sowing of spinach or mache.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.