Hi there, we have a potted olive tree that has begun to get some yellow leaves throughout. It's in a full day of sun here in Portland. I give it a good soak once a week, as I thought they like a dry soil. There is new growth on the top of the tree, but the yellow leaves are all throughout. I'm also wondering what the best soil would be for it? I've read someone mention soil-free, with just peat moss and sand? Thank you for any advice!