Well, not always. If you’ve bought fresh ginger to use, then use it before you freeze it. And If you know you’re going to be cutting the ginger into chunks later on (to be used to season a soup, for instance) then don’t freeze it whole, because it will be difficult to cut up frozen solid.
But if you usually grate your fresh ginger (like in today’s one-bowl meal, or in another meal I’ve featured, turkey tofu) then it’s definitely worthwhile to freeze it. Simply wrap the ginger whole, with the peel still on, in a decent-sized square of aluminum foil.
What are the benefits? First of all, freezing the ginger keeps it from drying out. Most ginger is sold in quantities much larger than the home cook will ever use at one time, and by tossing it in the freezer it will keep for months.
Second, I find it easier to peel the ginger when it’s frozen. Use a paring knife to peel the ginger and when it’s frozen, only its thin skin will come off.
Third, it’s definitely easier to grate and prepare when frozen. I use a Microplane grater and even with that very sharp grater, a mess of stringy ginger fibers will still form when grating the root fresh. Grate frozen ginger and you won’t have the same problem – just a pile of very fine gratings that will thaw and quickly integrate into whatever you are cooking.