Have you ever noticed trees with their trunks painted bright white while driving through the countryside or walking past an orchard? Although it might look like a decorative choice, this practice has a practical purpose. Known as whitewashing, it is an old agricultural technique used to protect trees from certain environmental conditions and potential damage.

One of the main reasons for applying a white coating is to reflect sunlight. Young trees and those with thin bark are particularly vulnerable to intense sunlight, especially during winter when warm daytime temperatures can be followed by freezing nights. These sudden changes can cause the bark to expand and contract, sometimes resulting in cracks and injuries. The white coating reflects sunlight, helping keep the trunk cooler and reducing the risk of sunscald.

Whitewashing can also make it easier to monitor a tree’s health. Although ordinary white paint does not eliminate pests, the bright surface helps gardeners notice cracks, holes, wounds, and signs of fungal growth during inspections. The coating is usually applied to the lower part of the trunk because this area is more exposed to temperature changes, physical damage, animals, and certain pests. Covering just a few feet of the trunk is often enough for this purpose.

Not every tree needs whitewashing, but it can be particularly beneficial for young, newly planted, and fruit trees growing in areas with strong sunlight or significant winter temperature changes. Traditional whitewash is commonly made from lime and water, while specially formulated tree coatings are also available. Household paint should not be used without checking whether it is safe for trees, as certain products can damage living bark. Healthy, mature trees growing in suitable conditions often do not need this treatment.