Why are the inner leaves of my Arborvitae turning brown?

Why are the inner leaves (foliage) of my Arborvitae turning brown?

Simply put, and in my experience, it is just a shedding process that helps the plant shed its old leaves just as any deciduous tree loses its leaves in the fall. Unless the whole bush is turning brown, this inside browning and shedding is very common in the late summer and fall months.

In my pictures here you can see the process of this shedding and this is normal. However, if the whole Arborvitae is browning and losing its leaves, then you have a bigger problem which I will address in other posts.

Arborvitae are very hardy shrubs and once established can be drought tolerant. However, browning leaves on the outside and inside of the shrub can indicate the plant is dying from a lack of water. If the leaves are turning a darker brown or even black, this can be a blight or fungal disease problem and needs further investigation. You also have to watch for bagworms and insect infestations but most plants in any landscape or garden can attract diseases and insects. Either way, you may be able to save the plant in the early stages of decline.

In my years of experience growing Arborvitae, I have found them to grow in the red clay soil of Virginia and grow during the bouts of drought and unrelentless downpours of springtime rains. I grow them in pots too and find them to give winter interest in the landscape with minimal care and watering.