If you are hanging the gourds in their natural state, a protective finish is an option.
However, if you are painting or otherwise decorating them, a polyurethane coat (either spray-on or brush-on)would help protect the finish.

Jan

i use a polyurethane coat as well,BUT you also must remember to bring these in during the winter.they will still weather if left outside,if you leave them plane and coat them,just sand them down a little and recoat if you need to.

I hang Martin bird gourds and i paint them with white enamel water base paint...Martin birds like white gourds and that is the easy way too do it...I have tried the natural way and didn't get as many birds...With the white gourds i have plenty fo birds..