What are the reasons that azaleas drop their leaves and die after being watered with organic fertilizer?

After azaleas are watered with a liquid organic fertilizer that has been composted, abnormal leaf drop and death may occur for the following reasons:

First, the eggshells and soybean residue may contain a small amount of table salt (sodium chloride), and the fine fibrous roots of azaleas are relatively sensitive to sodium ions, causing root rot, leaf drop, and death.

Second, the 5% concentration may still be too strong for the fine hairy fibrous roots of azaleas, or the fertilizer liquid left at the end may have an even higher concentration, making it hard for the plant to withstand.

Third, the timing of fertilization may be inappropriate. For example, after the flowers fade, when new root tips have just emerged, or under hot conditions with temperatures above 32°C, the absorption function of azaleas is very weak, which leads to fertilizer damage to the roots and causes the plant to drop its leaves and wither and die. In addition, azaleas are not suitable for watering with well water, especially deep well water. Long-term watering of azaleas with well water can easily reduce root vitality and cause the plant to die.

Azaleas should be fertilized according to the needs of different growth stages. Before flowering, apply phosphorus fertilizer as a supplementary feeding; you can spray the leaves or water the roots with 0.2% monopotassium phosphate, once every 10 days, for 2 to 3 times in a row. Stop fertilizing during the flowering period. After the flowers fade, wait 10 to 15 days before supplementing with nitrogen fertilizer; you can use a 3% organic fertilizer liquid or a 0.2% urea solution to promote the plant to send out new shoots and grow leaves. July to August is the high-temperature season, when plant growth stalls, so it is not suitable to fertilize. After the weather turns cool in autumn, it is the flower bud swelling stage, and more phosphorus fertilizer should be applied, once every 10 days. After winter begins, if the greenhouse or indoor temperature is below 13°C, the plant stops growing, and fertilization should also be stopped promptly.

When fertilizing azaleas, attention should be paid to applying thin fertilizer frequently, and organic fertilizer should not contaminate the leaf surface. Fertilization is best done on a clear evening when the potting soil is relatively dry, and then spray once with clean water the next morning, so as to help dissolve the fertilizer in the soil and make it easier for the roots to absorb.