When to Plant Garlic in Minnesota
Planting Date
In Minnesota, garlic is usually planted in the fall so that cloves are exposed to the cold temperatures (vernalization) that many garlic varieties require. Garlic can be planted in spring, but the plants often form single-cloved bulbs (called rounds) or they grow normal bulbs that are much smaller than fall-planted cloves (see our Planting Garlic in Spring guide for more info).
The best fall planting date for garlic depends mostly on where you live in Minnesota. Your goal is to plant early enough for the cloves to develop a large root system, while also planting late enough that garlic cloves don't sprout and show significant green top growth above the soil.
This means that the planting date can range from the beginning of September to the beginning of November, depending on your location and how long you want your cloves to settle in before winter.
In colder zone 3 regions of Minnesota, located in the Northern part of the state, where winter comes early, garlic can be planted as early as September 7 or as late as October 21.
In warmer zones 4 to 5 southern regions, including Minneapolis & St. Paul, where fall is a bit longer, planting can range from September 15 until the first week of November.
In Minnesota, if you plant your garlic early in the season, you can sometimes end up with a small amount of green top growth above the soil line going into winter. These first green leaves may die back if they are exposed to extremely cold temperatures, but the cloves will re-grow new leaves in spring, and the garlic usually won't be harmed.
A garlic clove that was planted early and emerged from the soil before winter. Notice the slight tip burn at the end of the first leaf.
Planting Depth
Garlic cloves can be planted 1 to 3 inches deep (top of clove to soil surface), and the roots will continue to grow as long as the soil is not frozen.
The deeper the garlic is planted, the longer it will take for the soil below the cloves to freeze. This means that deeper-planted garlic will usually have a slightly longer time period for its roots to continue growing before the ground completely freezes.
For growers planting later in the planting window, slightly deeper clove depth often gives the roots a little more time to fully mature before winter.
Mulching
Most growers in Minnesota mulch their garlic for winter protection. Mulching helps moderate soil temperatures and keeps cloves protected from fluctuating temperatures.
Mulching also keeps the ground from freezing until the coldest winter temperatures arrive. The mulch forms a blanket that prevents ground heat from escaping, thus keeping the ground warmer. This means that by adding a thick layer of mulch (such as straw) over garlic beds, it is possible to extend the growing season in the fall. The mulch cover allows the clove roots to continue growing into late fall and early winter, even as the outside temperatures have fallen below freezing.
Thick mulch also protects any garlic leaf sprouts that have prematurely emerged in fall and often prevents them from dying back to the ground level over winter.
Wheat straw is the most commonly used mulch and should be applied at least 4 to 6 inches (10 to 15 cm) deep directly over the planted garlic. Other types of mulch, such as oat straw, barley straw or hay, can also be used.
In early spring, some growers remove the mulch completely once the threat of extreme cold is gone. Removal helps warm the soil once the snow melts, minimizes disease during wet weather, and makes weeding easier during the growing season.
For more growing information, see How to Plant Garlic in Minnesota or our other Growing Garlic articles!
About the Author: John Cote owns and operates John Boy Farms and Garlic Boy Seeds with his Brother, Wife and family, who have been farming the same land for over 140 years. As an agronomist and experienced farmer, he helps others learn how to grow garlic successfully. He has written many articles and is the author of The Master Guide to Growing Big Garlic.