The easiest way to store rhubarb so you can enjoy it when it’s out of season is to freeze it: cut stalks into 1-inch pieces; lay them flat on a parchment-lined baking pan. Freeze until firm, a few hours. Transfer to freezer bags and store in the freezer for up to a year. Use frozen rhubarb the same way as fresh—in sauces, pies, and crumbles.
Martha Stewart Living, May 2014