How do you preserve fresh ginger?

If your goal is longer term preservation, freezing is one of the easiest methods and what I tend to do on occasions when I've bought a lot of ginger at once (for whatever reason). While you'll lose a little flavor with freezing, when used in cooking, I find it still works well and is often difficult to distinguish from fresh. And it's quite convenient: you can actually pull out a frozen piece of ginger, grate off what you need, and just put the rest back in the freezer.

As a side benefit, peeling and grating frozen ginger can actually be a bit easier than doing the same to fresh ginger. If you need chunks of ginger, though, you'll need to let it defrost a bit first (or, alternatively, cut before freezing if you have a standard recipe you want to use it for).

Like garlic, ginger is best stored cool but not refigerated, or it will rapidly dry out.

It will still dry on exposed faces of course, but you can just slice thinly off until you come back to usable flesh.

It may also start to resume growth. That's no problem, if anything I'd say it's good - it's indicative of freshness and good conditions.

A small pot (you can also find them sold specifically for garlic, and perhaps ginger - sometimes oven-safe too) on the side is ideal, failing that just any ramekin/bowl/shelf/whatever - a pot would just help maintain a stable temperature and avoid light.

I find it keeps for around a month at room temperature, longer cool. You may have better luck in the fridge if it's easier to keep sealed there than cool without.

Plant it. That preserves it pretty much forever. And you get more over time! You can keep it as a houseplant. Water it every month or so. It can be harvested whenever you like, you don't even need to wait for it to grow or mature.

I bought a piece of ginger, used what I needed and cut the remaining piece into 1-inch (2.5-3cm) pieces. I soaked the to-plant pieces overnight in warm water and planted them in pots (about 6 inches/15 cm deep and 8 inches/20 cm apart). If they have sprouting bits, put them on the top. Water them after planting and about once a month after that. They like sunlight, but not direct sunlight. Mines were really happy in front of my north-facing window.

If you want to use your ginger, just take it out of the ground (whether it sprouted or not). If it has grown more rhizomes (it takes about 4 months to do so), you can plant part of it back. Just give it a day to heal and perhaps another overnight soak before you do so.

You can find quite a bit of information about growing ginger on our sister site gardening.

Freeze it.

Put the ginger root in the freezer. When you want some ginger just put the frozen root in the sink hole and turn the tap on a trickle for a few minutes. The outside will defrost first while the inside remains frozen. Slice off the defrosted outside and put the frozen core back in the freezer until next time.

Bonus: There is no need to peel the ginger.

Note: This is the sink/plug hole