How these dates are worked out
For every NOAA climate station in a state that records frost regularly, we take the median first fall frost date (the day by which a 32°F reading has happened in half of years). The “typical first frost” is the median across those stations, and the range shows the earliest and latest station. The planting window adds one to three weeks, following the extension guidance in the questions below. The hard-freeze column is the same calculation at 28°F, a common definition of a killing frost.
A state average hides a lot. Mountain and valley stations can be a month apart, so treat the state number as a rough guide and check your ZIP for the dates nearest you. Our crop timing guide uses a slightly wider window, from the first frost to four weeks after.
Other signs it’s time
- Soil temperature. South Dakota State University Extension calls 50°F at 4 inches deep ideal. See our soil temperature guide.
- Ground freeze. The University of Vermont Extension aims for about three weeks before the ground freezes, which in the Northeast is usually mid-October to early November.
- Mulch after the freeze. Several inches of straw or shredded leaves, added once the soil freezes, limit frost heaving.
Mild climates
Counting from the first frost works best where winters are cold. Where frost is rare or comes very late (California, Florida, Hawaii, Puerto Rico, U.S. Virgin Islands), it stops being a useful guide: waiting for frost there would push planting into winter. Many Southern extension calendars recommend planting garlic in October or November instead, and some varieties grow better there if the cloves are chilled before planting. In states marked † (Louisiana, Texas), the typical first frost falls after mid-November, so the frost-based window may also run later than local advice. Your state or county extension office will have local planting dates and recommended varieties.
Planting basics
Break bulbs into cloves a day or two before planting and use the largest ones. Set them pointed end up, about 2 inches deep and 4 to 6 inches apart, in loose, well-drained soil with plenty of organic matter. Extension services advise buying seed garlic from a garlic grower rather than planting grocery-store bulbs, which are often varieties suited to a different climate. Harvest comes the next summer, usually late June to early August, when about half the leaves have browned.
Questions gardeners ask
When should I plant garlic?
In fall, after the soil has cooled but before the ground freezes. University extension services put it at about one to three weeks after the first killing frost (Minnesota says one to two weeks, South Dakota two to three), or roughly three to six weeks before the ground freezes. Soil around 50°F at a 4-inch depth is a good sign.
Is it too late to plant garlic?
Usually not until the ground is frozen. If you can still dig, you can plant. Late cloves have less time to root before winter, so plant a little deeper, mulch well once the soil freezes, and expect slightly smaller bulbs. Montana State University notes planting can run as late as November there.
What happens if I plant garlic too early?
Cloves planted into warm soil can send up green shoots before winter, and those shoots are easily damaged by hard freezes. That is why the usual advice is to wait for cool soil and the first frost rather than planting in late summer.
When is the first frost where I live?
It depends on your nearest weather station, and can vary by weeks within one state. The table here shows the typical station in each state. Enter your ZIP for the stations closest to you, or open your state’s page for every station.
Which state has the earliest garlic planting?
Of the states in this table, Alaska has the earliest typical first frost (Sep 22), so planting there starts around Sep 29. Leaving out the mild-winter states, Arizona has the latest (Nov 13), with planting around Nov 20–Dec 4.
Related
- Planning a fall garden
- Soil temperature for planting
- Cool- vs. warm-season crops
- How frost dates work
- Frost dates by state
Sources: NOAA NCEI 1991–2020 U.S. Climate Normals (frost dates); planting guidance from University of Minnesota Extension, South Dakota State University Extension, University of Vermont Extension, Michigan State University Extension and Montana State University Extension. Long-term averages, not a forecast.