It is easy how to keep your "Kunyit" fresh or how to let it germinate. Just put it inside a plastic bag and put some water.
Make sure you put some air inside. Place it over the window near your kitchen. After a few days new shoot will come out. Wait till roots develope. After two weeks you can see a new roots coming out of the rhyzome.
Place it in a pot. A good planting medium for "Kunyit" is the ashes from your garbage mix with garden soil. The more ashes the better for the plant. If you have problem in looking for the ashes you go and find good soil from the jungle or rubber plantation. Those soil is rich in organic. This plants need alot of organic. I make my own organic soil by gathering the leaves and let it rot by it self.