Last summer I decided to try forcing garlic as one would other bulbs. For my experiment I took two types of garlic, german hardneck porcelain and chesnok red purple stripe garlic. These are relatively late garlics for my area and last year the porcelain was barely coming up last Jan.
For both garlics I had two heads from the same source. I refrigerated one head of each for the month of October and kept the other head at room temperature. I planted all the heads on Nov 1st.
Here are the plants as of 1-19, the porcelain on the left, purplestripe on the right. In each rock ringed bed the refrigerated plants are on the right side.
Results: the cloves that were treated in the refrigerator are dramatically larger as of mid-winter, and comparable in size to neighboring artichoke and asiatic (early) garlics. I expect they will produce earlier and/or larger bulbs. I'll post an update at harvest time. This may be a method to allow garlics that are more suited to northern climates to be reliably grown in southern climates where they would otherwise mature too late when summer heat would cause them to be stunted.