What to add to this "soil"?

[jaxs]

If the stuff keeps improving at that rate they might be bagging and selling it before long.

 

[Fuddyduddy1952]

If the stuff keeps improving at that rate they might be bagging and selling it before long.

Of course it's trash dirt. I've been watering plants and they were barely living but just now I added a few scoops of compost I have. It's old horse manure from mucking out stalls. When I dug into it, full of large earthworms and smoking...I bet 100+ degrees. To me within an hour plants already look better!