LEAFLET NO: 630
Revised 9/93 -- Author Reviewed
AZALEA CULTURE FOR NORTH CAROLINA
M.A. (Kim) Powell
Department of Horticultural Science
North Carolina Cooperative
North Carolina State University
Azalea Culture. To insure a successful azalea planting, cultural
requirements, planting techniques, and maintenance should be well
Exposure. Azaleas prefer a cool, partially shaded site. Several
varieties can tolerate full sun but most prefer an area that is
not exposed to long periods of hot full sun and drying winds.
Soils and Planting. Azaleas grow best when planted in acid,
well-drained soils with a pH near 5.5. A soil rich in organic
matter is ideal for azaleas. Many folks mistakingly believe that
digging a planting hole 3 or 4 times larger than is needed,
adding crushed rock to the bottom and rich topsoil as a backfill,
will solve all drainage problems. Holes dug in poorly drained
soil will only fill with water and continue to hold this excess
over a long period of time -- irregardless of the size of the
hole. When soils are saturated, the amount of oxygen available
to roots becomes very limited.
Generally, it is recommended to prepare a raised bed. Elevate
the planting area to insure good surface and internal drainage.
Sometimes a hole should not be dug -- just plant at grade level.
Build up around the rootball with topsoil and plenty of organic
matter. The organic matter can be decayed pine bark, sawdust,
organic compost. Do not add fertilizer to the backfill at time
When planting balled and burlapped plants, be sure to remove any
nylon strings or wire from the rootball. The burlap can remain
around the rootball but be certain there is not a plastic liner
inside the burlap. Many containerized plants will become
pot-bound and will require special attention before planting.
The layer of matted roots around the outside surface should be
cut, loosened, or frayed out before planting. If not, the roots
will fail to grow out into the surrounding soil and plants will
be more susceptible to drought.
Watering. Watering newly planted azaleas is essential. If
planted in a well-drained soil rich in organic matter, frequent
watering will be required. Backfills dry out much faster than
the original soil around the plant. Be sure not to apply
quantities of water that will waterlog the media.
Mulching. A 3-4 inch layer of organic mulch around azaleas is
recommended. This will help to discourage weeds, prevent soil
crusting, hold moisture during dry periods, and maintain a more
uniform soil temperature.
Fertilizer. Azaleas grow best with a moderate and even level of
fertility. There are several special azalea fertilizers
available which are excellent when used at recommended rates
because of their slow release ability. Most homeowners will get
satisfactory results from an 8-8-8 or 10-10-10 analysis. Over
fertilization can cause severe damage. Therefore, split
applications should be made in March, May, and July. Small
plants, less than 12 inches in height, should receive 1
teaspoonful per application. For larger plants, a level
tablespoon per foot in height should be sufficient. For large
bed areas, 2-3 pints per 100 square feet can be broadcast.
Maintaining the correct pH (somewhere between 5-5.5) and
fertilizer requirement can only be determined by soil testing.
Pruning. Contrary to popular opinion, many azaleas do need
pruning. Pruning is especially desirable to produce more
handsome and compact growth for tall-growing cultivars. Any
heavy pruning should be done immediately after the flowering
period. Tall, rangy limbs that appear in the top of the plant
should be removed down inside the body of the plant. To induce
branching, pinch out tips of new growth between flowering and the
first of July. Later pinching will reduce next year's flower
production. Always remove any dead or injured branches when
shaping or heading-back azaleas.
Dwarf azaleas also benefit from pruning. This gives better shape
and improves flower clusters on established plants.
North Carolina Cooperative Extension Service
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