Azaleas are "the royalty of the garden". Some of the species or the many thousands of named
varieties are sure to meet your preferences and growing conditions.
All azaleas are in the genus Rhododendron. Azaleas are classified as being species or hybrids.
A species is a population that interbreeds and is reproductively isolated from other populations.
Seedlings from such isolated species populations look like the parents, or "grow true from
seed". Hybrids are crosses between other species or hybrids. Hybrids will not grow true from
seed and may be faithfully reproduced only from cuttings, which are clones of the mother plant.
Azaleas have been hybridized for hundreds of years. Around 10,000 different plants have been
registered or named; although far fewer are in the trade. This provides a very wide variety
of plants, habits, sizes, colors and bloom times to meet almost every landscaping need or
personal preference.
All North American species azaleas, also called native azaleas, are deciduous (drop their
leaves in the fall) with flower colors ranging from white to purple, pink, red, orange, and
yellow. Evergreen azaleas, native primarily to Japan, have flower colors including white and
various shades of purple, pink, red and reddish orange, but not yellow. Color patterns
include single colors and bi-colors as well as sectors, stripes and flecks. For many azalea
varieties, all the flowers on the plant are similar. For other varieties, the flowers on the
plant may be a mixture of color variations, with a different mixture from one year to the
next.
Growing Azaleas
Azaleas are relatively pest-free, forgiving and easy to grow plants. Their cultural needs
include:
- Moderate temperatures (USDA cold hardness zones 6 to 8, minimum - 10 to +20 degrees
Fahrenheit), although many varieties can thrive in much lower temperatures, and others in much
higher temperatures.
- High shade is preferable but some varieties do well in full sun. While more
sun typically produces more compact plants with more blooms, the blooms will not last as long.
- A mulch of pine bark, pine needles or wood chips helps to keep moisture in
the ground, even out changes in the soil temperature, and keep weeds out. An inch or so
around the root zone and a thicker layer between the plants is desirable.
- Azaleas do not like "wet feet". Good drainage is most easily provided by
planting azaleas with the tops of their root balls a few inches above ground level and
mounding the soil up to the plants. This is particularly important with heavy clay soil.
- Azaleas like most soil at their roots. This may require supplemental
watering through early fall, at least until plants are established in the ground for a few
years. Adequate water after bloom helps to produce more flower buds for next year. An
infrequent deep soaking is more effective than superficial sprinkling. The amount of water
needed depends on the soil, temperature, humidity, wind and sunlight. In a dry fall, water
heavily after a good frost, before cold weather sets in.
- To avoid cutting off next year's flower buds, do major pruning of azaleas
soon after they bloom. Shortening or removal of long slender stems with no side shoots and
cutting out dead wood may be done at any time.
Planting and Bed Preparation
One of the most important considerations for optimum performance of azaleas in landscape
settings is proper bed preparation. Provide a loose, very well-drained soil. Some soils
in Louisiana are clay based. Amend clay soils with sand and a generous supply of organic
matter, preferably pine bark. It is also recommended to raise the landscape bed 4 to 6
inches. Surface and internal drainage are critical.
Maintaining an ideal soil pH is also critical to azalea success. The
recommended pH for azaleas is 5.0 - 6.0, with 5.0 - 5.5 being ideal. Non-Indian azaleas are
more susceptible to problems caused by improper pH than Indian varieties. Soil pH needs to
be determined by conducting a soil test. Organic matter additions may modify soil pH, so
conduct a soil test after preparing the landscape bed.
When planting, set the azalea plants in the hole no deeper they were growing
in the original container. If properly mulched, azaleas can be planted even 1 to 2 inches
higher than the soil grade of the landscape used.
# # #
