I planted a North Star Cherry tree last August. A number of weeks ago the buds came out during a particulary early warm spell. The buds haven't opened yet even though all of the other trees have leafed out. About 3 weeks ago we had a stretch of very cold below freezing weather. Could that be the reason they haven't opened and what ?will happen to the tree if the leaves don't come out. Will the tree be OK until next year? Terri