I don't know anywhere on line but if you have a walmarts close by ,i've seen some that look about that size.
vickie

Hello,
I found the following source for peat pots of all size up to 13". That's pretty large. They also have every size smaller than that and you can buy in bulk to save money. The website hyper-link is the following:

http://www.novoselenterprises.com/products/jiffy.asp

I hope this helps!!!

Here is a link that might be useful: Extra Large Peat Pots