we had a 5 feet blue spruce planted in our yard of a new subdivision. But the top of the rootball is 2-4 inches lower than the ground level. I wonder if this is still ok, or do we need raise the rootball higher which might be very difficult?

Hello Lei, We learn more and more every year about how planting depth impacts the performance of transplanted trees and evergreens. Without knowing more of your situation, I would say that your evergreen is planted too deep. If this evergreen was recently transplanted I would contact the firm that installed it and let them know of your concern. Even with a warranty that covers your plant for a period of time, if it does not recover from transplanting, you will have lost a season or two and the replacement will also take a season or two to recover, so you lose 4+years. A plant that remains in stress will not grow well and be more prone to insects and diseases, and enviornmental stress, more so as it gets older.

I hope this information helps you resolve your concern with your blue spruce.

Sincerely, Richard Hentschel