When to plant garlic in USDA Zone 5b

Plan your garlic planting around local frost risk and soil temperature, then work backward from the harvest week your buyers need. The calendar below is a starting point, not a field-level weather forecast.

Chicago, Des Moines suburbs, central IL, upstate NY. Average last spring frost May 1, first fall frost October 6 — a 158-day frost-free season.

Zone fit: challenging
Garlic needs a long season and this zone averages just 158 frost-free days. Start early, use black plastic, and plan for row cover on shoulder-season frosts.

Key dates

Direct-seed outdoors
July 17 – August 7
Expected first harvest
March 21 – April 18
Fall planting window
September 1 – September 22
Fall harvest window
May 6 – June 3

Windows are calculated from your zone's average frost dates. Adjust ±1 week for microclimates, elevation, and your own frost records.

Spacing and soil

Plant spacing
6″
Row spacing
12″
Seed depth
2″
Soil temperature
45–60°F
Frost tolerance
hardy
Days to harvest
240 days

Grower notes for Zone 5b

Fall-planted only. Plant 4–6 weeks before first frost so roots establish before soil freezes. Harvest when lower 3 leaves brown.

Plant near: tomatoes, brassicas

Keep away from: beans, peas

Other alliums for Zone 5b

Same crop, other zones

Track your own plantings

BAU Farm Intelligence turns these windows into per-field tasks — indoor seed-start reminders, transplant dates, harvest projections — using your farm's actual frost history.