Azaleas belong to the genus Rhododendron and are among one of the most popular flowering plants in central Florida. Evergreen species are native to eastern Asia, and deciduous species are native to North America. Native azaleas are naturally hybridized in nature, resulting in many intermediate forms with unusual flower colors. In Florida, azaleas bloom from February to April, depending upon variety characteristic or climatic conditions. Azaleas are easy to grow, but like any other plant, there are certain conditions required for growing this plant successfully.
Light: Azaleas grow well under partial shade, but dense shade will reduce growth and flowering.
Soils: Organic, well-drained soils with a pH of 4.0 to 5.5 are best for azaleas. At higher soil pH, some micronutrients, especially iron, become less available to the plants and can produce nutrient deficiencies that will interfere with the normal growth of the plants. Organic amendments such as peat, compost or pine bark increase water and nutrient holding capacity while lowering the soil pH. A soil test for pH should indicate if soil amendments are necessary to correct the soil reaction. The Cooperative Extension office will do the test for a small fee.
Fertilization: A general fertilizer such as 6-6-6 or 8-8-8 can be used for azaleas. There are many "azalea fertilizers" available in garden stores, which usually take care of the guessing game of fertilizing azaleas. On sandy soils, it is recommended to make frequent but light applications of fertilizers. A general rule of thumb for fertilizing azaleas is to apply a double handful of fertilizer per plant (1/2 pound to a mature size plant) or use 2 to 3 pounds of fertilizer per 100 square feet of plant bed. Micronutrients should be applied with the complete fertilizer in the soil or to the foliage.
Planting: Azaleas should be planted at the same depth they had in the container or nursery. The hole should be about 12 inches wider and as deep as the root ball. Organic amendments such as peat, compost or pine bark can be used in the back fill soil at a rate of about one third of the total volume. An organic mulch with a depth of 2-3 inches will help in conserving water and control weeds. Plants should be spaced 3 to 5 feet apart.
Irrigation: Newly transplanted plants need to be watered frequently to insure proper moisture around the root zone. During dry periods, transplanted azaleas may need watering twice a week but established plants will only require watering every 7-10 days.
Pruning: Established azalea plants should be pruned shortly after flowering and before the flower buds set for the next season. Spring flowering azalea buds are formed in July. Pruning at this time or before the new flowering period will reduce the number of flowers produced per plant.
Propagation: Evergreen azalea cuttings are usually rooted when taken after the spring growth has hardened or matured, around the month of June. Cuttings about 3 to 4 inches long are considered best for propagation. Deciduous azaleas are propagated by seed or layering because their cuttings are difficult to root.
Diseases: Azaleas have a shallow root system and do not grow well in poor soils, make sure that water drains well because they are very susceptible to root rot diseases. Mushroom root rot often kills azaleas, especially those planted in sites with tree stumps or buried organic debris. Pests: Lacebug, white fly, spider mites, scale and the azalea caterpillar are some of the most important pests affecting azaleas in Florida. Use oil and soap based insecticides or a mild insecticide such as malathion or sevin to control them.
Al Ferrer Seminole County Residential Horticulturist
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