Azalea

Fertilizing

During the growing season, feed azalea bonsai with specialized azalea or rhododendron fertilizer, as these trees require acidic conditions. Use liquid fertilizers weekly or organic products at longer intervals. When the tree is flowering, either stop fertilizing or reduce to half strength. After flowering (around mid-May) until September, you can increase nitrogen levels to promote strong leaf growth. For liquid fertilizers, follow bottle instructions before flowering and consider doubling the dose after flowering when more leaf growth is desired.

Azaleas are unique in their fertilizing needs due to their acidic soil requirements. The fertilizer must be adjusted to match the very acidic pH value of the soil. Organic options like Biogold or Hanagokoro work well and can be applied before flowering since they take several weeks to become effective. The timing of fertilization is crucial for maintaining the tree's health and ensuring abundant flowering.

Placement

Azaleas thrive in sunny locations but benefit from afternoon shade during intense summer heat. During flowering, protect the tree from both rain and strong sunlight to extend the blooming period. While mature azaleas can handle some frost, they should be protected when temperatures drop below 40°F (-5°C).

For winter protection, these hardy outdoor bonsai can tolerate temperatures as low as -15°C in unheated foil tents. When overwintering, you can bury the pot in bark mulch up to the first branch - some leaf loss (up to 50%) during winter is normal and shouldn't cause concern. Never keep azalea bonsai indoors, as they are outdoor trees that require natural seasonal changes.

Pruning

Azaleas are among the few basally-dominant tree species, meaning their lower branches grow stronger than the upper ones. To maintain proper form, prune the base branches more aggressively than the top ones. After flowering, remove spent blooms and ovaries by hand - this is also the ideal time for other pruning work since new flower buds develop in summer. Delaying pruning can significantly reduce next year's flowering.

The timing of pruning is crucial for flower development. While azaleas tolerate heavy pruning and can regenerate from branches without leaves, all styling work should be done after flowering. For larger cuts, use concave pliers and apply wound sealant, as wounds remain visible on the smooth bark for extended periods. When wiring, use extreme caution as azalea wood is brittle and the bark is very thin - aluminum wire is preferred over copper due to its gentler grip. Distribute major bends over several years to prevent breakage.

Repotting

Repot azalea bonsai every 2-4 years, either in spring or after flowering. Since the flowering season can extend into July when conditions are hot and dry, spring repotting may be preferable, but ensure frost protection afterward. The roots require special attention during repotting as they are thin and matted, making them prone to tearing when separated.

Use only lime-free soil specifically formulated for azaleas, with Japanese Kanuma soil being ideal. Avoid peat-based potting mixes, as they become difficult to rewet once dried. To improve aesthetics, consider applying a top layer of Akadama mixed with humus (1:1 ratio) to hide Kanuma's yellow color. Don't add other substrates like expanded slate - Kanuma provides all necessary properties for healthy azalea growth.

Watering

Maintaining proper moisture is critical for azalea bonsai - they need consistent moisture but cannot tolerate waterlogged soil. During flowering, avoid watering over the blooms to prevent premature wilting. Instead, submerge the pot until air bubbles stop rising, which may be necessary multiple times daily during hot weather. Use rainwater or filtered water when possible, as hard tap water can damage the tree over time, causing stunted growth and yellowing leaves.

Traditional Japanese cultivation often incorporates Yamagoki moss on the soil surface to maintain humidity levels, which benefits the fine surface roots. The soil's acidity level is crucial - always use lime-free water and maintain proper soil moisture. If the root ball becomes too dry, submerge it completely in water until thoroughly moistened.

References

Bonsai Empire - Azalea Bonsai Care Guide Bonsai Shop - Azalea Care