Let your gourds ripen on the vines as long as possible. Wait until the stem turns brown, but harvest before frost. The fruit bruises easily, so handle it carefully. Cut the stems 2-3 inches above the fruit with a sharp knife, and dry off any moisture.
Most gourds will need some indoor drying time before they are ready to use. Wipe them down with a weak bleach solution and lay them out in a well-ventilated area to dry. Gourds are completely dry when the seeds rattle around inside. Small gourds will dry in less than a month, and large ones can take up to six months. If mold appears during the drying process, scrape it off with a knife. Thin-shelled gourds dry best when hung in a mesh bag.
Once the gourds are completely dry, remove the thin outer shells with steel wool. Now they're ready to decorate. Use a wax or varnish for protection.
Pick sponge gourds (luffas) when they are young and green for a soft sponge, or wait until they are yellow or brown for a hard, scratchy sponge. Soak them in water for a few days, then peel off the skin. To remove the seeds, cut off one end and shake them out.
Instructions for making a gourd birdhouse