I was thinking of storing it in a bucket i had but started thinking if it might grow fungus.

OK, I'll bite. Why would you want to store 'extra' soil? And how much are you talking about?

Trying to wrap my mind around the "extra soil" concept... same curiosities as rhizo!

I bought a big bag hatt was on sale but was only going to repot a few. Going to repot a few seedlings later but wating for them to get stronger. So for now wanted to store the dirt with out it getting bug or fungus in it and wasn't sure if leaving it in the garage that gets a bit warm around this time was a good idea. I live in Los Angeles. oh and I'm a newbie gardener!

I got a big bag of soil I didn't need at a yard sale and put it in a shed. Went to Alaska for three years. Upon return I opened the bag and all manner of insects flew out. The soil appeared fine so I used it for potting. I always imagined it was somehow improved by the insects but of course had nothing but my imagination to go on.

Ah....I get it now. I keep my extra potting medium in its original bag, tightly folded and taped securely with duct tape. I store it in my tool shed.

Oooh I see what you mean now. Ideally, I would do as rhizo, but realistically, it's extremely likely that there is a "bag in progress" sitting next to the area where I repot as we speak. But I can neither confirm or deny that it's leaning against the back porch right now... It won't last long, though. As soon as the gardenia at the abandoned house next door is finished flowering, I'm taking as many cuttings as I have dirt to fill pots, and I also want to try cuttings of a few shrubs at my Mom's house. The very presence of this "extra dirt" compels me to propagate.