care for frostbitten hornbeam trees My 12 year old hornbeams have now been bitten twice by the frost, each time losing some stems - once 7 years ago, and more recently this past Mother's Day. Several small stems have been lost, but more disconcerting is that the leaves mostly have a yellowish tinge, without the beautiful green that we're used to. What should I be doing to save the trees? Yellowing leaves indicate a stressed tree, usually a watering issue. To much or to little. If it has been dry I would compensate and water the tree to help it through the warmest part of the summer. Also mulching can help. 2 to 3 inches of a hardwood mulch will help retain moisture. Watch for signs of insect or fungus in the stressed tree. You could apply a light fertilizer now, but nothing to high in Nitrogen. Look for a balanced formula. 10-10-10. Then in late fall or early spring reapply again.