Leave the gourds on the vine until a light frost or the stems turn brown. If you need to pick a gourd before the frost, the gourd should be very firm to the touch. Cut the gourd with an inch or more of stem. Wash the gourds in soapy water. Dilute household bleach may be added to the water if desired, and may help delay mold formation. A light coat of non-glossy floor wax gives the gourds a natural glow.
Dry the gourd fruits naturally by placing in an area with good air circulation. Bringing the gourds indoors may help them dry faster, but gourds can be dried outdoors even in cold areas, however repeated freezing and thawing will affect the viability of seeds. When the seeds rattle, the gourd is dry and ready for crafting. How long it takes a gourd to dry depends on the drying environment -- the warmer and the better the circulation, the faster the water will evaporate from the gourd. Most moderate-sized hardshell gourds will be dry by Christmas. Larger or particularly thick-shelled gourds may not dry for several more months. Light may help to retard formation of mold, but the mold on the outside of gourds is a natural part of the drying process; as long as the gourd remain firm to the touch, do not discard it. Turning the gourds and wiping off the mold on a weekly basis may help the gourds dry sooner.
While the natural method of drying in time-consuming, it is still the best recommendation for drying gourds. There are a few other tricks which work for some growers but do not give consistent results for everyone. Some growers have luck using an ice pick to pierce the gourd to help it dry sooner. This may work depending on the environment; for most gardeners, however, this only serves to introduce mold and bacteria into the gourd which causes the fruit to rot. Another technique which works for some growers is to "bake" the hardshell gourd by putting it in a conventional oven (not a microwave!) at a very low heat with the door open to let the moisture escape; if the gourd is too "green" when this is tried, it may cause a lot of undesirable wrinkling of the skin.
"Greenscraping" of gourds may help gourds dry a little faster and may prevent some of the darker patterns of mold. It seems to work best if the gourd has a chance to dry out slightly first. Using the back (dull) side of a knife, scrape off the outer skin, revealing the lighter surface below. Place the greenscraped gourds in a warm, lighted, well-ventilated area; turn and wipe them off every few days. If the gourds dry too quickly, they may tend to wrinkle. The disadvantage to this method is the amount of time put into scraping if the gourd does not "cure".
Once the gourd is completely dry it is ready to be cleaned. Rattling of seed is a good indication of dryness; however sometimes the seeds adhere to the inside of the gourd and in this case the gourd will be very light and sound hollow when tapped. Submerge the gourd in a bucket of warm soapy water and scrape off the outer skin with the dull side of a table knife or a plastic mesh kitchen scrubby. Bleach may be added to the water, but it is not a necessity.
Using sandpaper or steel wool to clean dry gourds is OK if the gourd is going to be painted -- but there will be fine scratches from these abrasive materials which will show up if the gourd is stained with wood stains or a light coat of leather dye. Small holes or cracks can be filled with wood putty. Cut edges of gourds and the interiors can be sanded smooth.