Cultivation and Management Methods for Large Potted Azaleas

The Wuxi Azalea Garden where the author works mainly grows azaleas in pots. The garden has a number of large azaleas over fifty or sixty years old, which are quite difficult to manage. In addition, it hosts the annual azalea flower show every year, and after the show the azaleas generally resume growth about 20 days later, right when they face the extremely unfavorable hot summer for azalea growth. In order to strengthen azalea growth, we gave careful thought to the growing medium. Azaleas have shallow, fine roots and high requirements for potting soil. In the past we always used orchid soil as the growing medium for repotting. In recent years we found that the quality of some orchid soil on the market had declined, lacking fertility and tending to compact, so that after use azalea growth stalled or the plants even died. We also tried sawdust, but found that mixing peat soil, yellow sand and rice chaff gave better results (other regions can adapt this according to local conditions). It has the advantages of good permeability, smooth drainage, easy fertilization and easy availability, and it holds together better than pure coconut husk or pine needle soil, making it a fairly ideal growing medium. We carried out comparisons, and all azaleas repotted with this soil grew noticeably better than the others and recovered their growth more easily after the exhibition. However, newly repotted azaleas need special attention when watering: they must not be allowed to dry out completely before watering, otherwise it will be hard to water them thoroughly later.

Azaleas have a strong ability to sprout new shoots and put out vigorous water sprouts. Maintaining the graceful shape of potted azaleas and restoring their growth can be controlled and adjusted through pruning. In recent years, we gradually pruned some of the large potted azaleas; in addition to routine pruning, we also boldly carried out heavy pruning. The specific method is to cut out thin, weak long branches, old branches that spoil the shape, and branches that are too dense in the inner canopy, so that the remaining thick branches sprout again; the new buds forced out this way are more numerous and stronger, and the flowers are also larger. It must be noted during operation that the best time for heavy pruning is during the peak growth period in May and June. It cannot be done during the dormant period; forcing heavy pruning at the wrong time easily causes the buds to die back and the plant to die. Weaker plants should first have their soil changed before pruning, and be heavily pruned the following year once they have grown strong. When pruning, pay attention to the direction of the retained buds.

Azaleas like to grow in a semi-shaded, semi-sunny environment and are highly susceptible to pests and diseases, especially horticultural varieties, which have weaker resistance to pests and diseases, so timely control is needed throughout the growing season. Common insect pests on azaleas include red spider mites and lace bugs, and diseases include brown spot disease, little leaf disease, and occasionally leaf gall disease. Pest and disease control is mainly based on prevention, especially for diseases. When disease spot symptoms appear on the leaves, spraying is not very effective; in mild cases leaves drop, affecting the ornamental effect of the azaleas and the flowering quality of the following year, and in severe cases the leaves wilt and the whole plant dies. In addition, attention must be paid to improving the ventilation conditions of the site, increasing light in winter, applying more potassium fertilizer to improve disease resistance, and promptly burning collected diseased leaves.