PlantAlong

When to plant garlic in zone 9a

Plant for fall between Dec 3 and Dec 10. That is 1-2 weeks after zone 9a's median first frost, Nov 261. Across most of zone 9a that date falls between Nov 23 and Dec 23.

Why a range: zone 9a is defined by winter lows, not frost dates. Its ZIP codes have median first frosts from Nov 16 to Dec 92, 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 9a's frost dates.

Last reviewed
Stations
432
ZIP codes
1,671
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 9a. 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
Dec 31-2 weeks after first frost

Five digits. The calendar is computed on your device.

What each source says, applied to zone 9a

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 9a's median frost dates.

Table 1. Garlic rules from every source, at zone 9a's median last frost (Mar 2) and first frost (Nov 26).
SourceWhatRuleZone 9a median
Minnesota3Plant for fall1-2 weeks after first frostDec 3 – Dec 10
Wisconsin1Used abovePlant for fall1-2 weeks after first frostDec 3 – Dec 10
Texas A&M (E-502)4Plant for fall4-6 weeks before first frostOct 15 – Oct 29

Frost across zone 9a

  1. Last spring frostmedian Mar 2
  2. First fall frostmedian Nov 26
  • Frost-free season (median)
Figure 2. Frost dates across zone 9a, from 432 NOAA stations matched to 1,671 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.