PlantAlong

When to plant garlic in zone 5a

Plant for fall between Oct 12 and Oct 19. That is 1-2 weeks after zone 5a's median first frost, Oct 51. Across most of zone 5a that date falls between Oct 3 and Oct 27.

Why a range: zone 5a is defined by winter lows, not frost dates. Its ZIP codes have median first frosts from Sep 26 to Oct 132, so a single zone date can be weeks off for you. The rule comes from University of Wisconsin–Madison Division of Extension, Wisconsin Horticulture, written for WI and applied here to zone 5a's frost dates.

Last reviewed
Stations
655
ZIP codes
2,089
Photo: Chris F / Pexels
These dates use the typical last frost for the whole zone. Your ZIP code gives a closer answer.
  1. Plant for fallWisconsin
  • Start indoors
  • Plant outdoors
  • Range across the zone
  • Frost-free season (median)
  • Spring frost risk (90% to 10%)
  • Fall frost risk (10% to 90%)
Figure 1. Garlic in zone 5a. Dark bars: at the zone's median frost dates. Pale bars: across most of the zone's ZIP codes. Hatched blue: where the zone's last and first frosts fall.
Fall planting
Oct 121-2 weeks after first frost

Five digits. The calendar is computed on your device.

What each source says, applied to zone 5a

The same frost dates give different answers depending on whose rule you follow. These are all the published rules we hold for garlic, worked out at zone 5a's median frost dates.

Table 1. Garlic rules from every source, at zone 5a's median last frost (May 3) and first frost (Oct 5).
SourceWhatRuleZone 5a median
Minnesota3Plant for fall1-2 weeks after first frostOct 12 – Oct 19
Wisconsin1Used abovePlant for fall1-2 weeks after first frostOct 12 – Oct 19
Texas A&M (E-502)4Plant for fall4-6 weeks before first frostAug 24 – Sep 7

Frost across zone 5a

  1. Last spring frostmedian May 3
  2. First fall frostmedian Oct 5
  • Frost-free season (median)
Figure 2. Frost dates across zone 5a, from 655 NOAA stations matched to 2,089 ZIP codes.

Sources

  1. University of Wisconsin–Madison Division of Extension, Wisconsin Horticulture, Garlic, Allium sativum, Rev: 10/2023. Retrieved 2026-11-02.
  2. NOAA National Centers for Environmental Information, U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), 2021. Retrieved 2026-11-02.
  3. University of Minnesota Extension, Fruit and Vegetable News blog, Tips for garlic planting season, Page shows October 15, 2026; URL path says 2021/10 (unresolved). Retrieved 2026-11-02.
  4. Texas AgriLife Extension Service, The Texas A&M System, Texas Home Vegetable Gardening Guide (E-502), 2/09. Retrieved 2026-11-02.