There are hundreds of azalea and rhododendron cultivars to choose from. They vary in their mature size, flower color, and to some degree when they bloom. Most azaleas bloom in March or April. The gumpo types bloom in May or June. The newest types of azaleas, Encore, will flower twice -- once in the spring and again in late summer. Most rhododendrons bloom in late April or May.
Azaleas and rhododendrons are members of the same plant group -- both thrive in acidic soil. The pH should be between 4.5 and 5.5. Its best to have your soil tested to see if adjustments are needed to bring it to an acidic condition.
Most azaleas and rhododendrons grow well in a cool, partially shaded location. They can suffer when grow in full sun and will produce few flowers when grown in heavy shade. An ideal place is beneath tall pine trees. Generally, they do best on the north and east side of your home where they will be protected from the hot afternoon sun.
In selecting cultivars to grow, consider their mature height. Rhododendron should be spaced 5 to 6 feet apart. Large growing azaleas should be spaced 4 to 5 feet apart; low growing azaleas should be spaced 3 to 4 feet apart.
Azaleas and rhododendrons should be transplanted in late fall or early spring. They can be planted while in flower or peroid of active growth, but you will have to take special care to keep them from drying out during the summer. Do not plant azaleas or rhododendrons in clay soil without amending the soil first. They do not like poor drainage or poor soil aeration. Incorporate a 3- to 4-inch layer of organic matter such as pine bark mulch. This will improve soil aeration and drainage. Ideally, an entire bed should be prepared instead of digging individual holes. On sites that tend to remain moist, consider planting in raised beds. The hole for planting should be 2 to 3 times as wide as the root ball, but no deeper than the root ball. Plant at the same depth they grew in the container. Mulch with a 2 to 3-inch layer of organic matter such as pine straw or pine bark nuggets.
Azaleas and rhododendrons are shallow rooted plants. They are very sensitive to drought and excess fertilizer. Water during periods of dry weather. Fertilize lightly ---- over fertilization is a guaranteed way to kill azaleas and rhododendrons.
© Erv Evans, Consumer