I had (21) 2 - 2 1/2" maples B&B. Nineteen of them are in the ground with two still not planted. They have been sitting out for about five days and our temps have dropped into the mid 20's overnight. Are they still okay and if so what is the danger zone for damage due to the root ball freezing? I know I should have mulched around them but I kept thinking Iwas going to get them in the ground. What is your opinion?