Answer: If your newly planted trees and shrubs are dying with great regularity, I'd suspect a soil problem. Check to see how quickly the soil drains by digging a hole two feet deep and filling it with water. After it drains, fill it again. If this second amount of water drains away quickly (in an hour or so), the drainage is good. If it remains for several hours, or longer, the soil drains poorly. Plant roots can actually suffocate in poorly draining soils.
You can improve soil drainage by adding organic matter, but you'll want to do so over a large area, not just in the planting hole. Amending just the planting hole will encourage roots to stay in the immediate area instead of venturing out as they should. Good luck with your pin oak - and any future trees and shrubs you plant!
Q&A Library Searching Tips