Gourds make eco-friendly and effective bird houses. If made correctly, they can last up to 30 years. Pre-made gourd bird houses are easy enough to buy, but they do not offer the flexibility of a homemade one. By selecting the size of the bird house's opening, you can dictate the type of birds your birdhouse will attract. The decorating possibilities are virtually limitless. If you have a sizable crop, consider hosting a gourd decorating party. Or, decorate a few yourself and give them out as green gifts for bird enthusiasts.
Harvest your hard-shell gourd(s) when its vine has withered. An appropriately-sized gourd for a bird house has a diameter between 8 and 13 inches. Use pruning shears to cut the gourd's stem so that it is still attached to the gourd.
Dry the gourd for three to six months. Hang the gourd outside in a sunny spot, or lay it on a sheet of newspaper in a warm, dry place (but turn it frequently). As the gourd dries, it will start to mold. When it does, wipe it clean with a 10 percent bleach solution. If any of the gourds you dry begin to soften or wrinkle, throw them away. Your gourd is dry if the seeds rattle when you shake it.
Clean the outer surface. Use a wire brush and sandpaper to scrape off the mold and the outer skin.
Mix a 10 percent solution of bleach and water in a large bucket. Soak the gourd in the solution for 15 minutes. Remove the gourd and allow it to air-dry completely.
Cut out the entrance hole. Draw the hole to make sure it is in the right place. The hole should be slightly above the center of the gourd and face straight outward (not tilt up or down). Then use a hole saw (an expansion bit will work as well) to cut out the hole.
Remove the seeds and membranes from the inside of the gourd with a long-handled metal spoon (a wire coat hanger or serrated knife work just as well).
Cut two parallel, ¼-inch-diameter holes in the stem end. Later, you'll thread a piece of wire through these holes to hang the gourd.
Drill ventilation holes. Use a 3/8-inch drill bit to drill four to five ventilation holes in the bottom of the gourd and two or three in its neck.
Dip the gourd in wood preservative for 15 minutes. You may have to weigh it down with a gourd to keep it submerged. Then hang it out to dry for several days.
Sand the surface of the gourd lightly with fine sandpaper. Apply one coat of an oil-based primer. Allow it to dry completely.
Paint the gourd with two to three coats of enamel paint. The color is up to you, although white will reflect the sun and keep the interior of the bird house cool. If you want to maintain the natural coat of the gourd, skip the primer and enamel paint and apply two to three coats of clear polyurethane instead.
Hang the gourd. Thread a wire through the holes you made near the stem of the gourd. Secure the wire, then hang the gourd wherever you like.