Garlic (Allium sativum) is a hardy perennial member of the onion family. Garlic is probably native to Central Asia but has long been naturalized in Southern Europe. Garlic differs from the onion, producing a number of small bulbs called cloves, rather than one large bulb. Each bulb contains a dozen or more cloves, and is covered with a thin white skin. The larger outer cloves produce the best garlic. Garlic has flat leaves rather than the round hollow leaves of the onion.
Garlic grows best on friable (crumbly) loamy soils that are fertile and high in organic matter. Gardeners who can grow onions can grow garlic since the culture is similar. Garlic does well with high amounts of fertilizer. As a general recommendation, apply three pounds of 10-10-10 fertilizer per 100 square feet. Follow soil test recommendations for your particular garden soil. The soil must be kept evenly moist as dry soil will cause irregularly shaped bulbs. Heavy clay soils will also create misshaped bulbs and make harvesting difficult. Add organic matter, such as well-rotted manure or compost to the soil on a yearly basis to keep it friable.
Garlic must be planted very early in Ohio (March or April) to permit full leaf development. Later spring planting is not successful. It has been found that long days and warm temperatures favor bulb development in the garlic plant. As soon as bulbing starts, leaf initiation ceases. For highest yields, therefore, the cloves must be planted early enough to permit the development of large vegetative plants during the short, cool days of March and April. The yield potential of the plants depends on the amount of vegetative growth before bulbing begins. Select only larger outer cloves for the best garlic. Garlic seed is not available and is rarely produced by plants. Be sure cloves are free of disease, smooth and fresh. Plant garlic cloves 3-5” apart in an upright position in rows and set them at a depth of ½ -1” deep. Setting the bulbs in an upright position ensures a straight neck. Be sure to allow 18-30” between the rows. Do not divide bulbs into cloves until you are ready to plant since early separation results in decreased yields.
Harvest and Storage
The bulbs may be harvested when the tops start to dry, usually in August. Bulbs should be dug up rather than pulled to avoid stem injury. Allow the tops to dry. After the bulbs have dried, the tops and roots can be removed with shears to within an inch of the bulbs. It is essential the garlic be well cured before going into storage. The mature bulbs are best stored at 32ᵒF. Garlic stores well under a wide range of temperatures, but sprouts are produced most quickly at temperatures at or above 40ᵒF. The humidity in storage should be near 65-70% at all times to discourage mold development and root formation. Cloves should keep for six to seven months.
Source: OSU Ext.,Charles T. Behnke