Dowels are easy to store and don’t require maintenance.
Dowels should be stored in a dry place.
If stored in a damp place they can absorb moisture, which will cause them to expand and end up too wide for your screw holes. They could also go mouldy, which makes them unfit for use.
Dowel rods should be stored lying flat rather than standing on end.
If stored leaning against a wall, they can start to sag. This can make them unsuitable for use, as straight dowels are needed for joints.