Satsuki Azalea - Rhododendron
General Information: The azalea is a member of the genus
Rhododendron. It is an evergreen which in the wild grows as a small
shrub (up to six feet). There are hundreds of azalea cultivars. The azalea
used to be considered a separate genus from the rhododendron, but has
recently been reclassified.
The cultivar that is most commonly used for bonsai is
probably the Satsuki azalea. The most interesting feature of the Satsuki
azalea is that it produces flowers in multiple colors on the same plant.
The flowers can be white, pink or red, and can grow singly or in pairs.
Satsuki azalea originated in Japan and are more dwarf than other hybrid
groups. Satsuki means "fifth month" and these hybrids are late
partial sun. Avoid prolonged direct exposure to spring and summer
the tree (preferably under glass) in the winter, but do not bring
Keep the soil damp, as the roots can dry out easily and this is fatal to
the tree. Water with rain water if possible. If using tap water that is
high in lime, repot the tree every year to keep the soil acidity
every 20-30 days with a slow-acting organic fertilizer, from early spring
to late autumn, and apply chelated iron a couple times a year. Micro
nutrients should be applied routinely.
If you prefer to use chemical fertilizers, feed every
two weeks using a half-strength solution of a fertilizer for acid-loving
plants, such as Miracid.
If the tree is repotted in spring, do not feed until
autumn. Do not feed during the hottest month of the summer.
Pruning and wiring: Prune branches and new shoots in late summer, using a sealing
compound to seal wounds. Azalea can and will grow shoots from old wood.
New shoots at the ends of branches grow in groups of five. These shoots
should be reduced to two and the remaining shoots shortened to two sets of
leaves. Wiring may be done from spring through summer. Use care when
bending branches, as older branches are brittle. Skipping watering the day
before wiring will make the branches more flexible. You may need to
protect the bark by wrapping the wire with raffia.
Propagation: usually by
cuttings to maintain hybrid characteristics. Take 3 to 4 inch cuttings
after spring growth has hardened.
Repot in the spring after the flowers have gone by, every year for young
trees, every 2-3 years for older trees. Azaleas like well drained, organic
soils with a pH of 4.5 to 5.5. Some growers use pure peat moss, though
this is probably too extreme. Using a soil mixture specifically intended
for azaleas is advisable. Azaleas grow extremely dense, hairy root masses.
Experienced growers of azalea bonsai recommend using a soil mix that
contains no small particles at all, because of the dense growth of azalea
roots. If soil with fine particles is used, the roots can form mats that
shed water, making successful feeding and watering difficult. When
repotting, trim the root ball and cut out pie-shaped wedges around the
outside of the root ball so that the roots can grow into the
Pests and diseases:
Aphids, lacebugs, white fly, leafminers, spider mites, scale, stem
boreres. Diseases include petal blight, leaf gall, mushroom root
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