Azaleas

Brenda Parker was guest demonstrator at the Nepean Bonsai Society’s October meeting where she gave a timely talk on the care and maintenance of azaleas, one of her (and many others) favourite species for bonsai. In Japan special azalea bonsai festivals are organized around the time the trees flower.

Azaleas are excellent for bonsai. Their spectacular flowers, late in spring, come in many different colours, shapes, sizes and patterns making them one of the most popular flowering bonsai species. Satsuki azalea varieties are particularly popular, but Kurume azaleas also work beautifully. The small-flowered varieties tend to look more proportional on bonsai-sized trees.

Why azaleas work well for bonsai:

• Naturally small leaves that fit bonsai proportions.
• Spectacular spring blooms in whites, pinks, reds, and purples.
• Develop interesting trunk character and grow fine branches that result in beautiful ramification.
• Relatively forgiving for beginners.
• Can live for decades as bonsai.

Key care points:

• Need acidic soil (pH 4.5-6.0) – use ericaceous compost or kanuma.
• Prefer partial shade, especially in hot afternoons.
• Keep consistently moist but not waterlogged; azaleas do not like wet feet. Too much water can promote fungal problems. Azaleas like to be kept moist but not wet.
• Benefit from pruning right after flowering- remove both spent flowers and seed pods. Always seal any pruning site bigger than a chopstick with cut paste or putty to avoid die back.
• In Sydney, stop pruning at end of January, as the buds for next spring are starting to develop.
• Hardy in most temperate climates.
• The branches of an azalea can be brittle especially when the tree grows older, so be careful when wiring your tree.

Fertilising:
For an azalea to flower abundantly you need to time your pruning and fertilising well.
The following is Brenda’s fertilising regime:

• After flowering in spring, apply pelletised fertiliser, Brenda uses Osmacote for camellias and azaleas but not much as azaleas’ needs are low. These fertilisers are high in nitrogen and promote strong leaf growth.
• September to December she fertilises once or twice with a half strength liquid fertiliser.
• From Christmas to Mothers’ Day Brenda uses a liquid high potassium fertiliser monthly to promote flower development.
• If there is a weak area or the tree has become lignified (woody) use a high nitrogen fertiliser to stimulate fresh growth in weak areas or for replacement of woody areas.

Pest and disease control:

• Regularly inspect for pests like thrips and lace bugs, especially on the underside of leaves. Remove by hand if possible.
• To combat lace bugs, Brenda uses a systemic spray (Sharpshooter, Contender, Conquer or Confidor) three times between September to December but only after flowering has finished.
• Watch for fungal signs like brown/black patches on leaves or root rot and disinfect tools between cuts to prevent the spread of fungus.

A healthy plant is more resilient to pest attack and responds much better to the maintenance techniques applied them.

Repotting:

• Azaleas can be repotted at any time (even when flowering) because of their fibrous root system.
• Every 2 years for developing material and when necessary for more developed trees.
• Brenda removes about a third of the root mass from the bottom, slicing it off with a sharp knife or saw. Next, gently removes spent soil from the top surface and then teases out the roots from around the sides and bottom of the root mass, making sure to remove the dead centre under the trunk.
• Repot.