Will Frost Kill Garlic?
Frost will NOT kill garlic.
More Info: Under most conditions, frost will NOT kill garlic. It's hardiness will depend on the type of garlic and the zone in which you live.
Many an herb garden has suffered damage from frost during the winter season. When deciding the best time to plant your garlic, it is important to consider its hardiness concerning cold temperatures and frost.
Varieties of Garlic
There are two basic types of garlic: softneck and hardneck. Softneck garlic is somewhat less hardy in terms of withstanding extremes in temperature. This type of garlic is the most familiar variety for most gardeners and is characterized by a soft, papery pseudostem. In general, softneck garlic prefers a mild, dry climate. Hardneck garlic is easily cultivated in colder areas.
Garlic and Cold Climates
Both varieties of garlic are considered hardy and frost-resistant in gardening zones four through nine. In general, you should plant garlic in the fall before the ground has had an opportunity to freeze. If you live in a climate zone that does not often experience freezing temperatures, you can sow garlic almost year-round. However, if you live in an area that rarely receives cold temperatures, you may need to artificially simulate cold temperatures for your bulbs prior to planting. If you live in a climate zone that experiences extreme cold, it is a good idea to plant your garlic in early spring rather than fall. While your garlic is indeed hardy and tolerant of frost, extremely cold temperatures can stunt its growth.
Cold weather is actually very beneficial for your garlic. It grows best when allowed to enjoy a period of cold followed by a period of sunshine and warmth. This early exposure to temperatures below 40 degrees is so important that some sources suggest refrigerating bulbs prior to planting to simulate this temperature variation and stimulate maximum bulb development.
Overall, the relative frost tolerance of garlic makes it a hardy addition to your herb garden.