Down comforters are a luxury on a cold winter night, especially if they are well maintained and cared for. Down keeps its natural warmth and loft if you fluff it daily when you make the bed, and lie under it, not on it. Weight eventually breaks up the clusters of down, causing them to compress and fall apart. Crushing a down comforter into a plastic bag for summer storage makes a little extra fluffing necessary.
Take the down comforter to a laundromat. Most home dryers are not big enough for this task. Take a few tennis balls with you.
Put the down comforter and the tennis balls in the dryer. Set the dryer on a medium temperature and let it run for a full 30 minutes.
Remove the down comforter from the dryer, folding it lightly without pressing it down. Take it home, shake it out and put it back on the bed.
Gently shake the down comforter daily when you make the bed to keep it fluffy. The more the comforter has air circulating through it, the fluffier it will be.