Outdoor rugs are made of plastic for a reason: And that reason is MOLD.
This is what three days’ worth of rain quickly made of this natural fiber rug (World Market, 2006).
Do yourself a favor and if you’re going to decorate a patio, either paint a design straight on the concrete or purchase an outdoor rug. If you do so, you may spare yourself the loss of an old rug friend.
My Friend Staci 
Awww sorry about the rug! Is there any way to dry it out or salvage it? Maybe if you poured some hydrogen peroxide on it?
You mentioned an excellent idea! Painting a design on the concrete :) How cute!
I’m sorry about your rug. I could only imagine the smell from being left outside in the rain :(
♥Carrie
http://ilovebeingonline.com