Washing and drying your down jacket the right way is essential before storing it for a long time; you can read our guide on how to wash your down insulation here. If you wear your down jacket weekly, it’s recommended that you should wash it once every two months; for less regular users, washing it once a season is plenty. Some brands even offer kit washing services, if you’re not confident doing it yourself.
Once you’ve washed and dried your jacket, hang it up instead of folding it or putting it into a stuff sack. A down jacket’s performance relies on its filling, and compressing it can cause the down to clump together and lose its insulating effectiveness. This is the same for synthetic insulated jackets, although synthetic filling isn’t as sensitive to compression so can be stored folded in a pinch.