While not as convenient as powder, flake or paste forms, fresh garlic will far surpass the latter in both health-promoting and culinary prowess. Choose garlic cloves that are firm and plump with dry skins, avoiding those that are soft or shriveled, moldy or have begun to sprout.
No need to refrigerate your garlic; just store it in a cool, dark place uncovered and it should last for a month. Once you’ve broken a clove from the bulb, it will only last about a week.
Why buy organic garlic?
Conventional garlic is often treated with chemicals to prevent sprouting, besides the usual pesticides, and often isn’t grown regionally when purchased from your grocery store, so buying organic is always wise.
Source: http://www.organicauthority.com/vegetables/garlic.html