Re: Rooting hormone. I didn’t know you were meaning it for plants that are already in the ground.
There is a product by Fertilome (I think?) that is used to soak and then pour on the soil, for bare root trees and shrubs. We used to sell it at Jung’s when someone bought a bare root item.
My OLD computer is giving me heartburn this morning, but if I can find it for you, I’ll send you a link and you can look at the make-up of the product.
Yes, a splash of milk might help the Opo situation. I would give it 1/4” cup at the base of the plant, then water that in.
Can’t hurt, might help! When I have an empty 1-gallon milk jug I always fill it up with water right away with any of the little drips of milk still in the bottom. I use that on houseplants and my porch pots in the Summer months. Works really well; it’s a CHEAP fertilizer for all blooming things.