The answer to 'why is my hedge brown patches' is that there are several common causes, including drought, pests, disease, or improper pruning. Brown patches in a hedge can be a sign of stress or underlying issues that need to be addressed.
One of the most common causes is drought - if the hedge isn't getting enough water, the leaves and branches will start to turn brown and die off. Pests like aphids, spider mites, or scale insects can also damage the hedge and cause brown patches. Fungal diseases like leaf scorch or canker can also lead to brown, dying foliage. Improper pruning, such as cutting too much at once or at the wrong time of year, can also shock the hedge and lead to brown patches.