What causes azalea leaves to turn yellow and withered?

Poor care after azaleas finish blooming one year often leads to withered buds the following year. When azaleas are in bloom, people usually like to display them indoors for viewing, but this means stale air and insufficient sunlight. In the Shanghai area, where the climate is on the warm side, they can be moved outdoors at night and kept indoors in a bright spot in the morning and evening. After the flowers fade, gradually increase the time spent outdoors; after one week they can be placed in a shaded spot outdoors, and the spent flowers should be cut off promptly. Apply a nitrogen-based liquid fertilizer once every 10 days to encourage new shoots. From June to August the weather is hot and azaleas grow slowly, so fertilizing can be stopped. In late September, apply a phosphorus fertilizer once every 10 days to promote the growth of the plant and flower buds. Stop fertilizing after late October. In winter, move them into a greenhouse, place them in a bright spot, and keep the room temperature between 5 and 15°C. If the temperature deviates from this range, the plant will sprout new leaves, consume nutrients, and this will affect flowering the following spring. In addition, Satsuki azaleas tend to produce offshoots at the roots and stems in late spring; if these are not pruned away promptly, they compete with the parent plant for nutrients and affect flowering.

Azalea leaves turn yellow because the soil lacks iron or is on the alkaline side, or because of improper care; if measures are not taken in time, this can also cause flowers and buds to drop.

A lack of iron in the soil hinders the synthesis of chlorophyll, causing the leaves to turn yellow-white, most noticeably on young leaves. A 500-fold ferrous sulfate solution can be watered on once every 7 days until the leaf color turns green again. If the soil's pH exceeds 6.5, the leaves will also turn yellow; apply the ferrous sulfate solution in the same way as above, and once the plant has returned to normal, repot it into an acidic potting soil based mainly on leaf mold. If the light is too strong or too weak, if watering is excessive, if fertilizing is improper, or if the soil is heavy and clayey, all of these can cause the leaves to turn yellow. Provide appropriate shading, control watering, fertilize moderately, and use a loose, acidic potting soil.