Before harvesting garlic, it is best to discontinue watering for two weeks. This assures that bulbs begin the dormancy and curing process in soils that will not promote rot. Harvest garlic when the green tops turn brown and die down. It typically takes 90 to 100 days for spring-planted garlic to reach this stage. Pull up, or use a spading fork to get them out of the soil, and let dry for a couple of days. You can trim the leaves off before curing if you don’t cut into the bulb.
To cure, spread the garlic bulbs out, or hang them in a warm, airy place out of the sun such as a covered patio. They can also be covered with a light-weight cotton sheet that will provide shade but allows good air circulation. Do not use plastic or heavy fabrics that will restrict air movement around the bulbs. Cure for two to three weeks and then store at 40-60 degree F temperatures.
For more information, see the following Planttalk Colorado™ script(s).