Question
I don't have a question but a comment. I am a certified arborist in Northern Indiana and enjoy reading the questions and your answers. I pick up information about trees in other parts of the country. I do have one concern about your answers on planting. You recommend refilling the hole with good top soil. When you have clay soil, you will create a bowl which will drown the newly planted tree if you do that. It has always been my understanding and from everything I read that you want to fill the hole with the same soil that came out of it. Your opinion?

Answer
With clay soil you will need to make sure that the sides of the hole are not smooth. I have seen folks that used a machine auger type to dig the hole and this created a "pot in the ground". IF you use this type machine to dig the hole I would make sure you dig into the sides of the hole and the bottom to allow water to seep out or you can get a pot that will hold water and kill the root system. When digging in heavy soil the sides can become slick especially if the soil is somewhat wet. Slick sides can act as a physical barrier to root growth and moisture movement. Use a shovel to make the sides of the hole rough and irregular. I would not put just the clay back into the fill but at least add potting soil mixed with the clay. The clay soil tend to clump and when put back can be compressed into the hole which will cause problems. IT all depends on the soil type where you are. IF what you are doing works--good. We have some clay soil here in Alabama that would just clogs to put back into the hole. Good top soil or potting soil would be best in that situation. I try to give general recommendations since I usually do not know the soil type involved. I hope this answers most of your concerns.