When we buy garlic, they usually make us to buy 2 for $1. The problem is we can never finish them in time before they turn black! We end up throwing them away. Here is a tip of what I usually do to make sure we don't have to dump them. You can do this with ginger or green onions.
Cut the root off.
Peel the skin off
Done peeling!
Put them in the food processor
Blend them!
Put them in a sandwich bag. Make sure to make them flat. Put them in the frezzer. When you need to use garlic, just break a small piece. (this is why you have to make sure to put them in a thin layer in a sandwtch bag)