This is Luffa ægyptiaca, giver of sponges for scrubbing with. After a long summer of tracking garden dirt inside, not cleaning under my fingernails, and allowing the overfull laundry basket to sprout horns and hooves and crouch in a corner of the bathroom like an ogre... it's time to clean house.
Cleaning house is boring, unless you have your very own luffa sponge that you grew all by yourself, and then it's kind of fun, at least for a little while.
Luffas need a long season to produce, which we don't have in northeastern Pennsylvania, but I did get one sponge off my vine, and that's all I need. Like I said - I'm kind of a crappy housekeeper.
I start my luffa seeds (available from Fedco) indoors under grow lights, and set plants out after danger of frost, when the soil has warmed. They need as much jump on the season as you can give them. Luffas like to scramble, so the clothesline is a good place for them, especially if you don't intend to do laundry. They send out tendrils every which way, and hightail it wherever they are headed.
Our vine produced one early fruit, which I left to mature and dry, and then cut after frost. If the fruit is totally brown and dry when you cut it, you just peel the skin right off - all that's left inside is the dry sponge and the black seeds.
We had one short, late dry spell this year. In a season as wet as this one was overall, a dry spell is really stressful on annuals that don't have their roots down deep and are accustomed to guzzling as much water as they please. The luffa vine panicked and set fruit - lots - all of a sudden. But the season wasn't long enough to mature this young fruit. Hence the single sponge.
I think I will cut it in half or thirds, depending on how many things I decide to scrub... two, or three?