[header] How to hang a wreath on a storm door [title] Buy a suction cup hook with a sufficient weight rating. [step] Clear, flexible suction cups with metal hooks attached are easy to find online or at many home goods retailers. Before buying, though, check the packaging for a maximum recommended hanging weight. 
[substeps] If you have a very lightweight wreath-one made primarily of plastic or fabric, for instance-any decent suction cup hook will probably do. For bigger wreaths, though, weigh them before suction cup shopping.