The first time you notice rows of trees with their trunks painted white, it can seem unusual. The bright coating stands out against the natural landscape, making it easy to assume it’s for decoration or to mark property lines. In reality, this simple practice has a practical purpose: protecting trees from seasonal damage that is often invisible until it is too late.

One of the biggest threats trees face during winter is a condition known as sunscald. On sunny days, the sun can warm one side of a tree’s trunk while the opposite side remains frozen. When temperatures drop rapidly after sunset, the warmed bark cools too quickly, causing it to crack. These injuries create openings for insects and diseases, weaken the tree, and can even prove fatal, particularly for young or recently planted trees.

To reduce this risk, growers and landscapers apply a white coating, typically made from diluted latex paint. The white surface reflects sunlight instead of absorbing it, helping keep the trunk at a more consistent temperature throughout the day. By minimizing dramatic temperature changes, the coating greatly lowers the likelihood of bark splitting during cold weather.

The white paint serves much the same purpose as sunscreen does for people—it protects against harmful exposure in a simple, affordable way. Farmers, gardeners, and municipalities commonly use this technique to help vulnerable trees survive harsh winters and remain healthy for years to come. So, the next time you see a row of white-painted trunks, you’ll know they represent a thoughtful form of protection rather than decoration.