Our pussy willows are well established. I plan on building up the area where they are planted with 8 to 10 inches of soil, covering the root line. Will the pussy willows survive this or will I smother them?
Building up soil around the base of the tree will inhibit gas exchange by cutting off the supply of oxygen to the roots. The excess soil will also encourage root girdling, which will eventually lead to the death of the tree. It is recommended to keep excess soil/mulch at least 4-5 inches from the root flare of the tree to ensure good health.