Is there a specific fertilizer to use on my Camperdown Elm?
I live in Zone 9.(PAC-Northwest)
Certified GKH Gardening Expert
These don't really need an extra fertilizer. You want them to grow a little more slowly to avoid contracting Elm Disease, which is a huge problem once it gets established.
If you still choose to fertilize them, you will want to choose a fertilizer you will want something with low nitrogen, and high phosphorus and potassium. You want this to be in slow release form, too.
Really, it is best to plant them in the correct soil, light, and area to get the most from the trees, as it is tedious to fertilize them without accidentally causing the death of the tree.
This article will give you more information on the care of the tree: https://www.gardeningknowhow.com/ornamental/trees/elm/camperdown-elm-tree-information.htm