Gourd growers that have a large field or garden in which to grow their gourds and live in a warmer climate, usually leave them in the field to dry right on the vine. This is the easiest method of drying. But if you have a small garden or raised garden boxes as I do, this method is not the easiest method. Also I live in a colder climate with temperatures below zero for long periods of time.

I do not dry my gourds outside, but carefully place my gourds on wooden pallets inside my garden shed all winter. The temperature in the shed gets cold, but the gourds are not exposed to ice and snow that would cover them if left outside to dry. Green skinned gourds tend to damage easier being exposed to such weather extremes. Drying the gourds on wooden pallets allows air to circulate around them. They need this circulation because the water content in each gourd leeches out through the skin and needs the air circulation to evaporate and not cause rotting.

Turn your gourds often! This allows for even drying and water evaporation. Your gourds are 90% water and need to shed this water to become completely dry.
Also do not let your gourds touch each other. If you want to wipe off the moisture leeching out from the skin, you can use a rag that has been soaked in a mild bleach and water solution. If you have grown a large crop of gourds, this method may not work for you, but for a smaller crop it works great!

While on the wooden pallets during the winter, your gourds will begin to mold and turn brown and black. This is normal. Some of my gourds have the outer skin flaking off as well, and visible fuzzy mold growing on the outside. Even though this is not a pretty site, I know this mold and coloring will leave unique and fascinating patterns on my dried gourds after cleaning them. Some gourd artists prefer gourds with natural patterns that enhance their works of art.

DO NOT DRY YOUR GOURDS IN THE HOUSE!
The mold growing on the gourds could cause breathing problems and make your home environment toxic. Always dry gourds outside or in an outside garden shed with good ventilation.

Some gourds can take up to a year to dry. The smaller ones maybe just a few months. A fully dried gourd will feel light as a feather. If you lightly tap on the shell, it will sound hollow. If you shake them you can sometimes hear the seeds rattle inside. When the drying gourd has any of these characteristics, it is ready to begin the cleaning process.