When to plant garlic in USDA Zone 5a

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.

Madison WI, Des Moines, southern MN, central MI. Average last spring frost May 8, first fall frost September 29 — a 144-day frost-free season.

Zone fit: challenging
Garlic needs a long season and this zone averages just 144 frost-free days. Start early, use black plastic, and plan for row cover on shoulder-season frosts.

Key dates

Direct-seed outdoors
July 24 – August 14
Expected first harvest
March 28 – April 25
Fall planting window
August 25 – September 15
Fall harvest window
April 29 – May 27

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 5a

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 5a

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.