So, yes, this article is about when to fertilize azaleas and how to do it right, but it is also appropriate info for the feeding of rhododendrons, too. The yellowing older leaves on this azalea may indicate a lack of nitrogen in the soil, but they could also indicate plant stress. But these signs can also be a symptom of soil that is excessively wet or compacted, or even an insect or disease issue. From there forward, test the soil every few years to determine whether or not more fertilization is even necessary.

They are forced to bloom out of season which requires a huge expenditure of energy on the part of the plant. It contains a wide range of trace elements including iron that prevents leaf yellowing caused by lack of iron. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. If they are grown in soil where the pH is too high (alkaline), they produce poor growth, few flowers and the leaves tend to become yellowish in colour.This concentrated feed is ideal for all ericaceous and acid loving plants such as berberis, magnolias, heathers, hydrangeas, pieris, blueberries and raspberries.

This is the first year I have decided to feed my azaleas and camellias, after having several years of unimpressive flowers. see “Signs of over fertilization” section below) Soil acidifiers are a good option if your nutrient levels are good but the soil pH is too alkaline. Organic soil acidifiers work best to support the correct pH balance and nutritional needs of azaleas.Insects and mites like scale, lace bugs, aphids, and spider mites are drawn to tender, over-fed foliage.