Mountain laurel is a broad-leaved evergreen shrub, native to the United States where it is much beloved. Mountain laurel usually remains green year round, so brown leaves on mountain laurels can be a sign of trouble. Determining the reason for brown mountain laurel leaves can be challenging and involves careful detective work. The following information may help.
Why Mountain Laurel Leaves are Browning
Below are the top reasons for brown leaves on mountain laurels:
Desiccation/winter burn – Brown leaves on mountain laurels can be caused by desiccation, which occurs when winter wind draws moisture from the tissues. If the plant is unable to pull moisture from the soil, the water in the cells isn’t replaced and leaves turn brown. To prevent desiccation, ensure the tree is properly watered during dry periods.
Cold temperatures – Damage can occur when winter temperatures are unusually cold, but it is most likely to occur in trees planted in the northern borders of their USDA hardiness range. An organic mulch will help during the winter. If necessary, protect mountain laurel trees with a burlap windbreak.
Improper watering – Brown mountain laurel leaves, primarily when browning shows up at leaf tips, may be due to improper watering or excessively dry soil. Always water the tree deeply every seven to 10 during absence of rain by allowing a hose or soaker to soak the ground for at least 45 minutes. A layer of mulch will keep the soil evenly moist but be sure to leave a span of bare ground around the stem.
Fertilizer burn – Strong chemical fertilizer may be the reason for mountain laurel leaves turning brown, especially if discoloration affects the tips and edges. The tree may be absorbing too much fertilizer without your realization if it’s planted close to a heavily fertilized lawn. Follow fertilizer manufacturer recommendations closely. Never fertilize dry soil or a thirsty tree.
Sunburn – When mountain laurel leaves are browning, it may be because the tree is exposed to too much intense, direct sunlight. Mountain laurel shrubs prefer plenty of morning sunlight but should be in shade during the afternoon.
Drought – Established mountain laurel trees are relatively drought tolerant, but they aren’t likely to tolerate long periods of extreme drought. Mulch is critical to help mountain laurel trees survive drought and summer heat.
Disease – While not often an issue, mountain laurel shrubs do suffer from occasional fungal problems, especially in areas with abundant humidity and moisture. Leaf spot is the most common of these and will cause browning of the leaves. Fungicides can help.