Now is the time to plant Luffa seeds. Many people (including me) thought that loofahs were related to sea sponges, but in fact they are grown in the garden. Plant them by a fence or trellis.
These would make great Christmas gifts if you let them dry out or you can eat them before the drying stage (they're like cucumbers)
After the luffa has dried, peel off the shell/outer skin and shake out the seeds.
Soak the loofah in warm soapy water with a little bleach, then leave them to dry. Cut the top and bottom off and use the middle part as an exfoliant scrub in the bath or shower or cut into smaller pieces to use as a dish scrubber in the kitchen.
Pictured instructions here