Fertilization Methods and Technical Key Points for Azaleas

Azalea roots are delicate and tender, so fertilizer must be fully composted before use. Generally, fertilizer that has been composted for more than 1 year and fully fermented is most suitable. Five points should be noted when fertilizing:

Feed according to the seedling. Seedlings cannot be fertilized; after 4 months, a well-composted, extremely dilute liquid manure can begin to be applied; after the plants are established and transplanted separately in the following spring, more nitrogen and potassium fertilizer should be applied to accelerate vegetative growth. At 2-3 years, during the mature stage, more phosphorus fertilizer should be added to achieve a high flowering rate and large, brightly colored flowers. In the old-age stage, more nitrogen fertilizer can be applied to promote renewal of branches and leaves, rejuvenate the plant body, and extend the plant's lifespan.

Fertilize at the right time. From February to March in early spring, begin applying a light fertilizer mainly of nitrogen and potassium to promote the sprouting of branches and leaves; April to May is the growth and development period, when branches and leaves are luxuriant and roots sprout rapidly, so phosphorus fertilizer should be the main component, supplemented by potassium fertilizer, once every 5 days; stop fertilizing during the dormant period of intense summer heat; during the autumn growth period from August to September, apply dilute phosphorus and potassium fertilizer again, once every 10 days; in early winter, a base fertilizer such as soybean cake can be applied once as a supplementary dressing.

Apply thin fertilizer sparingly. Azalea roots are as fine as a hair, and throughout the entire growth process, fertilization is required to be sparse and dilute. If too much is used or the concentration is too high, not only can the roots not absorb it, but reverse osmosis will occur instead, drawing the cell sap out of the plant body, burning the root hairs, and causing yellow leaves, dried shoot tips, and even death. If this happens, fertilization should be stopped immediately, and water should be applied continuously to dilute the fertilizer solution in order to save the plant.

Use base fertilizer with caution. For 2-3 year old azaleas, each year in early winter a small trench 3 cm deep can be scraped along the inner wall of the pot, and a small amount of dilute, fully composted base fertilizer mixed with livestock and poultry manure and soybean cake can be applied once, then covered with a thin layer of soil, after which it will slowly seep into the soil with watering. Because the fertilizer absorbs sunlight and heat and releases heat at night, it also helps the plant grow in winter.

Control water before fertilizing, and water heavily after fertilizing. Before fertilizing, the potting soil should be dry; otherwise, the fertilizer remains in the mud and cannot spread, ventilation and water permeability are obstructed, and root rot easily occurs. After fertilizing, water heavily the next morning so that the fertilizer fully penetrates and dissolves, which is conducive to absorption by the plant.

It is particularly worth mentioning that azaleas like "green manure water." A large vat or cement pool can be used to soak and compost vegetable leaves, green grass, melon rinds, orange peels, rapeseed cake, and so on, covered with plastic film, increasing heat through sunlight and fully fermenting and composting. Then take the upper clear liquid and add 1/5 green manure water to each normal fertilizer application, with remarkable results. Green manure is rich in organic matter, is slightly acidic, and has mild fertility, does not harm the root system, and can make the plant grow robustly.