The guy at the grow store, who I just met, sold FF soils, but when I told him what I wanted to do, he recommended a soil produced by a semi-local maker that came in a few different strengths. He said for an auto the lightest one was probably best. He said it's what he's used for years in all his outdoor grows with tremendous success. I'm in a small town and he seemed pretty straight up*, so I was going to trust him. It was a big bag for $37, but I didn't get the name nor recognize it. Now that I think about it, I'm pretty sure I don't need anything that big, so I'll check what the FF bags sold for first. He had Happy Frog and Ocean (something). Which would I need for this? If it's successful I may do it again in the future, but only with autos. There are bright sodium vapor lights 40 yds away on both sides of my yard, so I would think that would affect photos at night? If my little seed sprouts and does well in its solo cup, I'll swing by the store again and get the name of that local stuff.
*I needed some ph down and was going to get some Advanced Nutrients since he didn't have GH in stock, but instead he sold me some CES for $6 less and also because he had found the ph didn't climb as bad on him after mixing it. I'm always leery of salesmen, but he seemed okay.