How should rhododendrons be fertilized correctly?

Rhododendrons are flowers that do not need heavy fertilization. If too much fertilizer is applied or it is too concentrated, it will instead be harmful to their growth. But this is not to say that no fertilizer should be applied at all. To make them bloom abundantly and produce large flowers, it is still necessary to apply some fertilizer at the right time and in the right amount. Therefore, flower-growing experts have summed up their experience with fertilization in 8 words: "Apply dry fertilizer sparingly, apply liquid fertilizer thinly." This is very appropriate and worth referring to for flower growers. Under normal circumstances, 1-2 year old seedlings do not need fertilization, because the fertility contained in the humus soil is already enough to supply the needs of seedling growth and development. For small plants 2-3 years old, starting from late spring or early summer, a dilute cake fertilizer solution or dilute alum fertilizer solution can be applied once every 10-15 days. For plants over 4 years old, about 20 g of dry cake fertilizer can be applied each spring and autumn. In mid-June, a quick-acting phosphorus and potassium fertilizer can be applied once to promote flower bud differentiation. After June, fertilization can be stopped. After the flowers fade, which is exactly when new branches are growing, a liquid fertilizer with a slightly higher concentration can be applied once, but it must not be applied too concentrated, and raw fertilizer must not be applied, otherwise it will damage the root system. Applying too much fertilizer in summer will cause old leaves to fall off and new leaves to turn yellow. It is particularly worth noting that for rhododendrons grown at home, the most likely problem is not a lack of fertilizer in the plant, but damage caused by excessive fertilization. If situations such as yellowing and withering of leaves occur due to too much fertilizer, fertilization must be stopped immediately, the dry fertilizer removed, and more water applied to wash away the fertilizer accumulated in the soil. After watering, move the plant to a ventilated place for care; some need to be rinsed 2 times. In this way, after half a year it can gradually return to normal growth.

If no abnormality appears in summer, then after the Beginning of Autumn, the rhododendron will begin its second period of vigorous growth. During this short period, 1-2 applications of a dilute solution of phosphorus fertilizer such as superphosphate can be given to supply the plant's needs for growth and bud formation. After each fertilization, clear water should be applied 2 days later, and the potting soil should also be loosened once to allow the soil in the pot to be fully aerated. After winter begins, as the weather gradually turns colder, the plant stops growing, and fertilization should also be stopped immediately. If fertilization is not stopped and the plant sprouts tender leaves, it will instead make it harder for the rhododendron to overwinter, so one must never be careless.