Cucurbita, or ornamental gourds, are members of the cucumber family and related to squash, melons and pumpkins. They're used most often for making decorative items and birdhouses. Some crafters of gourds advocate picking them from the vines when they've only partially hardened. Holes are then drilled into the gourds in keeping with the theory that fluids will drain and curing will be accelerated. This practice is not only messy, it's more likely than not to cause the gourd to rot. To be on the safe side, let nature takes its course and leave your gourds on their vines as long as possible before removing for drying and curing.
Harvest your birdhouse gourds just before the first predicted frost for your area. They're ready when the stems dry and turn brown. Cut them from the vines but leave a few inches of stem attached to each. Inspect the gourds carefully for bruises or soft spots. Pick out immature pieces, or any that feel rotten. Throw these undesirables on the compost heap.
Wash the birdhouse gourds with soap and warm water and pat them dry. Wipe them down with rubbing alcohol.
Set the gourds in a single layer so that they're not touching each other on a wire cooling rack or slatted wood pallet. The idea is to allow for good air circulation. Place them outside in the sun for a week. The colors will set during this time as the outer shells harden.
Move the gourds to a well-ventilated, warm, dark, dry spot indoors for a week. Look them over for the presence of mold and check them for soft spots each day. Throw away any that become moldy or soft. The exteriors of the remaining fruits should be hard and dry in about seven days.
Place the birdhouse gourds in a single layer without touching each other in a shallow cardboard box to begin the internal drying process. Put them back in their warm, dry location. It may take anywhere from another one to four months to complete the curing process.
Turn your gourds every day so that they'll ventilate evenly. While you're handling them, check for developing mold on their exteriors. At this point, just wipe it off with a soft cloth and return the gourds to their warm spots in the box. Discard any that become misshapen, soft or shriveled. Your birdhouse gourds are ready to be crafted when you can hear seeds rattling around inside and the dried gourd feels light.