Both hard shell and ornamental gourds can be cured and dried, however, hard shell gourds (Lagenaria types) will typically have thicker and stronger walls than ornamental gourds (Cucurbita). Drying time will also usually be longer for hard shell gourds.
To begin drying gourds, you must ensure that they have matured fully. If growing your own gourds, you can make reasonable effort to make sure they are matured simply by leaving gourd fruit on the vine as long as possible. Hard shell (Lagenaria) gourds should remain out on the vine at least up to the point where gourd vines become brown and withered, possibly even throughout the fall and winter months as long as there is protection from or no major threat from deer and ground hogs which enjoy snacking on gourds. Ornamental (Cucurbita) gourds should be left on the vine up until the point that the fruit has become hardened and not easily compressed. It is advisable to not allow ornamental gourd fruit to remain on the vine longer than necessary as they will likely undergo additional attacks from insects and disease as well experience undue fading from sun exposure.
When buying green, un-dried gourds from a seller, you have to be careful to make sure you select gourds that are as mature as possible and have the best chance of drying properly. Gourds you find that can bend easily and are somewhat wobbly when shaken and very small for their cultivar size are gourd fruit that are immature or much later fruit sets on gourd vines and not good candidates for dry and curing. If gourds have soft dark spots on them, then the gourds are in the process of rotting. Matured gourds will have often have dark spots like these on them also, but they will remain hard and not become soft indicating the gourd is in the drying process. Gourds that have any of these soft spots on them will for sure not dry and harden properly and they can only be used as decoration or for seed saving purposes.
After finding mature gourd fruit, you are now ready to begin the drying process. You will begin by finding an open space with good air circulation such as in an open storage shed, garage or leave them in the field (only if they are hard shell gourds). If you dry the gourds in an semi-enclosed area (ideally with open windows or doors if possible), you will want to spread gourds out over a piece of wood sheathing or card board, preferably not directly on the floor as some gourd fruit may rot and cause a mess and likely some staining. Although, you may follow all steps properly and make every effort to avoid having rotten or immature gourds, you will almost certainly have a few.
For hard shell gourds as they begin to dry, you will begin to see the skin naturally peeling off and mold begin to grow on the gourd fruit surface. This is a normal process for curing and drying gourds, however, if skin becomes soft, toss out fruit (unless you plan to save seeds) as it is beginning to rot and if not discarded soon it will become messy and smell very bad. It’s a good idea to check on gourds every few days and turn them so as to allow even air circulation around gourds and when necessary discard rotten fruit. You can expect the process of drying and curing gourds to take place in one up to approximately five months depending on gourd size and thickness. For this reason ornamental gourds cure and dry much faster than hard shell gourds. While gourds are curing and drying in place, they may encounter the freezing temperatures of the winter months; this should not be cause for concern as this will not in general be harmful to the gourds.
After the curing and drying process has been completed, the gourd fruit will have a hard surface that is covered in mold and weighs perhaps a quarter or less of its original weight (of course if the fruit remained on gourd vines longer, they should have already begun this drying and weight loss process prior to harvesting). You can clean off this mold (which is naturally occurring) scrubbing it off using a wash rag and / or steel wool in warm, plain water. You may want to wear latex or rubber gloves while cleaning the gourd fruit as the mold can become quite messy. As you are working to clean this mold off, the gourd surface should remain wet so not to allow mold particulates to become airborne, which it’s best not to breathe in if possible. After cleaning gourds, you can disinfect them by washing them in very mild (1 part beach: 10 parts water) solution or by wiping them with a Clorox wipe.
Now after gourds have been cured, dried and cleaned, they are ready to be used or crafted as you would like.
RESOURCES / REFERNCES:
Grassbaugh, Elaine, Metzger, Susan & Riofrio, Marianne. Growing and Curing Gourds in the Home Garden, HYG-1630-96. Ohio State University Extension Fact Sheet, Horticulture and Crop Science. Retrieved from: http://ohioline.osu.edu/hyg-fact/1000/1630.html
Rood, Mary Ann. (1998). North Carolina Gourd Society, Tips on Growing Gourds
Retrieved from: http://www.ncgourdsociety.org/growing.htm