As others have said....where you are, or, more to the point, what your climate is like would be the deciding factor. If you have 30 days, or more, until your ground freezes (or if you live someplace it DOESN'T freeze !) I'd plant them in the ground, and either "pin" them to the ground with landscape staples, or weight them down (at the first sign of freezing soil) with a brick. If you don't have 30 days, I'd put them someplace cool and dry, and plant them in the spring....if you choose this route, give the roots (not the whole rhizome)a good two day soaking in water before you plant them.
And,

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