Once your spoil is prepared (Growing Gourmet Garlic: Planting Part 3 – When to Plant and Soil Preparation) choose a likely day for planting, and crack your bulbs accordingly. Bulbs of gourmet garlic should not be broken apart (or "cracked") until one or two days before planting. We crack ours on the day of planting whenever possible. Cloves begin to deteriorate once separated from the root plate, so leaving the bulbs whole until the last minute keeps the cloves in optimal condition.
Bulbs can be separated mechanically or by hand. At Calling Quail, we crack thousands of pounds of garlic each fall. To make the process more efficient, we have a dedicated "cracking" machine, composed of two large adjustable rollers that gently squeeze the bulbs apart. This process does not separate each individual clove, but it does break the bulbs into halves and quarters. The remaining pieces are then cracked by hand.
Softneck cultivars are cracked with relative ease. They possess multiple rows of cloves and lack the central stem of hardneck varieties, both of which aid the cracking process. To crack a softneck cultivar, hold the bulb in one hand while applying gentle downward pressure with the thumb of your other hand to the outer layers of skin. Once the skin has been removed, the exposed outer layer of cloves are easily removed from the rest of the bulb. Repeat this process on the inner layers of cloves until all have been separated.
Hardneck cultivars are more difficult to pop, due to the woody stalk. To crack, carefully break the skin around the top of the cloves and down one side of the bulb. Grip the bulb with one hand, and insert the thumb of the other between two of the cloves or, at the very least, get a good grip of both sides of the bulb. Apply a gentle pressure, twisting slightly if required, and pull the bulb in half. Holding the stem along with one of the halves while cracking will provide you with greater leverage, making the process easier.
While cracking your garlic, examine each clove to separate good planting stock from bad. Check each clove for signs of mold, disease, or damage, and discard these cloves. Cloves should also be firm and relatively plump. The skins on each individual clove need not be intact, but extra care must be taken with skinless cloves while you are planting, since the lack of outer skin makes them more vulnerable to damage.
Examine the base of each clove to determine whether or not the basal plate (the small brown crater at the bottom of each clove) is still intact. As this small plate is where the roots and leaves originate, it needs to be in good condition to produce a robust root system. If only a small piece of the plate is missing the clove can still be planted because the prolific growth of the roots will often compensate for its absence. Keep in mind, however, that missing portions of plates expose the clove flesh to bacteria that may be present in the soil.
When planting certain Rocambole cultivars, such as Russian Red, you will come across a significant number of double cloves - two cloves in the same skin which have not fully separated. Planted whole, double cloves will produce two plants that grow against each other resulting in full, but often misshapen, bulbs. If you are planting gourmet garlic for your own consumption these malformed bulbs are not an issue, since they taste just as delicious as those perfectly formed. On the other hand, if you are planning to market your garlic, the double cloves should be separated or eaten. Successful separation is difficult when the double clove is not completely divided. If you cannot split the joined cloves without damaging the flesh, put the cloves aside for another use.
If you are planning to plant your cloves in sections based on size, separate them accordingly while cracking the bulbs. For most cultivars we have a series of buckets; one each for the larger cloves, the smaller cloves, and the determined doubles, one for the damaged cloves for eating, and a last container for any too compromised by damage or previously unnoticed disease that will be discarded. Any moldy or diseased garlic we burn to prevent contamination of our other stock. Once your garlic is separated, store the cloves as you did the bulbs.
Want to read the other parts in this series? Check out:
Growing Gourmet Garlic, Part 1: Where to Get Seed and How Much to Plant
Growing Gourmet Garlic, Part 2: Choosing Which Bulbs to Plant
Growing Gourmet Garlic, Part 3: When to Plant and Soil Preparation
Growing Gourmet Garlic, Part 5: Spacing, Planting and Mulching