During the offseason store we suggest storing your decoys out of direct sunlight in a shop, garage, enclosed trailer etc. whether in single or slotted bags. To avoid dents and flattening avoid putting weight on top of your decoys and stacking decoys on top of each other. Your spread will be in great shape and ready to go when the next season rolls around.
Or we recommend using your decoys as house decorations while not in use during the offseason... really, the wife will love it.