There seem to be several form of D. binata multifida. I think the answer depends of the form, the temperature the plant is subjected to, and photoperiod. I can only speak to my limited experience. I grow multifida at three places: my unheated greenhouse at home (where the temp occasionally gets near freezing in winter), my outdoor artificial bog (where 30F is not uncommon in winter), and a heated greenhouse at Humboldt State University (where the min temp is kept above 60F). At my home greenhouse and bog, multifida completely dies back to the roots, with all leaves dying. In my greenhouse, the multifida plants have now put out new leaves. In my outside bog, they are still dormant with no sign of new growth (although within a few weeks they will begin to grow again). At the HSU greenhouse, multifida never dies back in winter, although growth of new leaves slows noticably (probably because of reduced photoperiod). At least that is my experience.