Azaleas and rhododendrons add their beauty to the spring flower show. These flowering shrubs are generally carefree. Occasionally, azaleas and rhododendrons require light feeding to boost their health and blossom production. Feeding them at the right time will ensure their continued health and beauty for several years.
Most azaleas and rhododendrons require very little supplemental feeding. Give them spare feedings of ammonium sulphate or similar acidic fertilisers, if necessary.
Leaf chlorosis, or yellowing foliage, is a sign that azaleas or rhododendrons need an application of a balanced acid-based fertiliser.
Rhododendrons and azaleas that have yellowing at the point at which the leaves join the stems may benefit from a light application of Epsom salts to the surrounding soil, which supplies supplemental magnesium, a necessary nutrient for this family of plants.
Azaleas and rhododendrons mulched with fresh sawdust or wood chips are more likely to require supplemental feeding. Plants mulched with pine needles or similar material usually don't require additional fertiliser applications.
Feed azaleas and rhododendrons in late winter or early spring, and never later than July 1 in most areas. Feeding after this date will encourage new growth that will not have time to harden before winter, encouraging dieback at the plants' growing tips.