Light Intensity
In general, pot mums benefit from maximum available light, especially in winter months. Be careful not to shade crops with overhead baskets. Under periods of high light and temperatures in greenhouses, petals can scorch and turn brown, especially in red, bronze and deep pink varieties. The Charm family of varieties is particularly sensitive to these conditions, and an inner ring of burnt petals will often develop.
To prevent this sunscald, provide shade with cheesecloth or a 20 to 25% shade fabric above the crop as flowers begin to open. Also, take extra care not to water stress crops under these conditions.