I have a regular common variety elm. The kind if you see in your yard taling root you hit it with round up. I recently put it in a new pot after trimming the roots. i used miracle grow potting mix for my soil. Is this correct. Most of my collection is Ponderosas collected from the mountains which I use Turface, fine mulch and small pebbles for a mix so I am new to Elm trees. Any thoughts? Dave in Sunny Colorado.