You may have noticed that some trees have their lower trunks painted white. This is not for decoration but to protect the bark from sunscald, a condition similar to sunburn in plants. Sunscald commonly occurs in winter when fluctuating temperatures—from cold nights to sunny days—damage the bark. The white paint helps prevent the tree from overheating and cracking, which can expose it to diseases, fungi, and pests. This treatment is usually done on young, thin-barked residential trees or in orchards until they become more resilient.

White paint helps moderate daytime heating of the bark and reduces the risk of sunscald. Other colors and markings convey different instructions, such as indicating disease, the need for removal, or pruning requirements. In forests, paint can mark hazardous or safe trees, private hiking trails, or nests of endangered species. However, there is no universal standard, so check local guidelines before making assumptions. In many states, purple paint marks private property.

If you decide to paint trees white, choose the right product. Use water-based latex paint diluted with one gallon of latex to four or five quarts of water. Avoid oil-based paint, as it can seal the bark and prevent the tree from absorbing oxygen. Any light color works, but darker shades absorb more heat and worsen sunscald. Apply with a paintbrush, as sprays are less effective.

One coat is generally sufficient unless weather conditions are extreme. In areas with severe weather, reapply annually. Young trees benefit most from this protection. By understanding the reason behind painting trees white, you can help young trees grow strong and healthy while avoiding common mistakes that might harm them.