How do, ThelmaLou!
I used to worry about paper cups falling apart too fast, and used plastic Dixie cups instead.
Now, I saved my paper coffee cups for a year. I figure, if I'm giving plants away and want to urge people to pot them up or plant them out before they get root-bound, what better way than to tell them "now, you have to pot this up before the paper cup dissolves and you have mud everywhere!
(Actually, I bet they last a long time.)
>> will use the food grade h2o2 later.
If you have access to food grade hydrogen peroxide, it might be 32% strong! The recipes that we toss around are based on "drugstore peroxide", which is 3%. So 1-3 ounces per quart of drugstore peroxide is fine, but if you start with the strong stuff, you might want to try 2-6 teaspoons per gallon so you don't bleach any seedlings blonde.