The answer to 'why is my patio brown patches' is that there are several common causes, including drought stress, fungal diseases, and weed infestations. Brown patches on your patio can be an unsightly problem, but there are usually straightforward solutions.
One of the most common causes of brown patches is drought stress. If your patio doesn't get enough water, the grass or plants can start to turn brown and die off. This is especially common during hot, dry summer months. The solution is to increase watering, either manually or with an irrigation system.