Colorado has a great climate for growing garlic (Allium sativum), and October is the best time for planting. Garlic needs four to six weeks to establish roots before the ground freezes and the plants go dormant. When selecting garlic there are two different groups: hardnecks and softnecks.

Hardneck garlic loves cold winters and many people prefer hardneck varieties because of their larger cloves. Hardneck cloves are also easier to peal because of their loose skin, which is why their storage life is shorter than the tight-skinned softneck varieties. Hardneck garlic has cloves growing around a hard central stalk and is believed to be original descendants from wild garlic.

Softneck garlic forms more cloves with large cloves around the outside of the head and many small ones at the center. They do not send up a flower stalk and are more difficult to peel because of their tight skins. Softnecks also tend to keep longer once harvested.

Garlic needs loose, fertile soil. Spread a two or three inch layer of organic matter and aged manure over the area and dig it in. Soggy soil is an invitation for disease and rot. Heavy soil, especially clay, not only limits bulb size, but also can encourage fungal disease. Garlic needs nitrogen for leaf growth and potassium and phosphorus for the development and growth of the bulb and roots. Garlic is a poor competitor with weeds. Unless weeds are controlled early in the spring they can easily overtake young garlic plants, causing significant yield losses.

A bulb of garlic consists of many individual cloves, and when planted, each clove can grow into a new garlic bulb. Select clean, dry bulbs for planting, being careful not to nick the cloves when separating the bulb. A simple nick can create opportunities for disease, especially in wet soil. Plant the cloves the same day as they are divided.

Plant the unpeeled cloves with the pointy side up in a sunny location. Rows should be 12 – 18 inches apart and the cloves gently inserted 2 to 3 inches deep and 4 to 6 inches apart. Irrigate immediately after planting. Garlic cloves require 4 – 6 weeks of cool weather (less that 40 degrees F) after planting to vernalize the plant so it will produce bulbs. During fall and winter, the bulb will produce roots and some top growth. Using mulch will keep the soil moisture levels even and protect against frost heave.

After the weather warms up in spring, long, strap-like leaves will emerge and lengthen. Each green leaf represents a wrapper layer surrounding the garlic head. The plants will need water during spring and early summer. Top flowering garlic will produce seed stalks in late spring which should be removed to allow energy to go into bulb formation.

In June to early July, leaves will turn brown and the top will begin to wither. Irrigation should be stopped so bulbs will not rot. It is time to harvest when the top growth has dried. Loosen the soil with a garden fork so that the bulbs can be removed. Dry the garlic in a well ventilated location out of direct sun. Curing garlic can take two to six weeks and well-cured garlic can last a long time. Softnecks last a year and hardnecks last four to six months. They can be cleaned and trimmed, but the cloves should not be separated until you are ready to use them. The largest bulbs should be set aside for planting in the fall.

Varieties of garlic depend on personal taste. Popular hardneck varieties include Spanish Roja, Carpathian or German red. These all produce large, easy-to-peel cloves and tend to be on the hot and spicy side. Softneck varieties include Inchelium Red, California Early, Chet’s Italian, Mild French and Silverskin. These are milder and produce smaller cloves. Elephant garlic, named for its large size, is very mild in flavor and is not true garlic, but related to the leek; it needs more growing space than hardneck or softneck garlic.

For more information, please see Colorado State University Cooperative Extension Fact Sheet #7.614, “Onions and related species”

The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.

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This page updated:  November 1, 2006