Sims azalea
(Rhododendron simsii)
Country of Origin : South China
Bonsai Styles : Formal upright, informal upright, slanting, semi-cascade, clump, Broom
Zone : 8 – 10
Azalea genus is huge and has hundreds of species that come in a wide array of colors, flowers, and shapes. In fact, there are bonsai grower groups that exclusively create and share their azalea bonsai trees.
The small-flowered dwarf azalea types are ideally suited as houseplants and bonsai.
Another azalea species which is probably the most famous among bonsai growers is Rhododendron indicum ‘Satsuki azalea’. Click here to read more about the Satsuki azalea bonsai tree.
Sims azalea is a subtropical, evergreen, beautifully-colored, flowering shrub. They are prevalent in the cool, damp, shaded valleys of their subtropical habitats.
It usually has small, shiny leaves that range in color from light to dark green, and flowers that bloom between mid-autumn and mid-spring. The flowers emerge in clusters of single or double pink, white, crimson or red color.
Read more about other bonsai trees species in : Types of bonsai tree
Best location to keep Sims azalea bonsai tree
Is rhododendron simsii an indoor plant?
Rhododendron simsii can be grown in a fairly cool location indoors throughout the year. Keep it near a cool west, north or east facing window. The light from a south facing window can be too much for this plant. 500-1000 Lux is the minimum amount of light it will require to flourish. Please read the light levels required by bonsai to know the light requirements of various indoor bonsai trees. Also read how to grow indoor bonsai using grow lights. It is important to protect the bonsai from harsh direct sunlight, however.
Sims azalea will thrive indoors only if they are provided with a lot of fresh air and light, as well as a moderate temperature.
It can also be kept outdoors from late spring to early autumn in a partially shaded location.
In winter, keep the bonsai indoors in a well ventilated and bright location. A suitable temperature range for this plant in winter is between 42°F and 53°F (6°C and 12°C).
Also in the winter, when the buds start to develop, move the bonsai to a slightly warmer location with a temperature between 59°F to 71°F (15°C to 22°C).
It is advisable to keep the bonsai outdoors again when the bonsai has finished its flowering.
Click here to read our detailed guide to indoor bonsai tree care.
IMP: Refer to do bonsai trees need sunlight for more indoor and outdoor bonsai location ideas. Also, refer sunlight requirements for indoor plants for more indoor gardening ideas.
Propagation of Sims azalea bonsai tree
Sims azalea can be propagated through cuttings. However, it is somewhat difficult. Because it is slow and difficult to root and will need the right amount of constant bottom heat for rooting.
If you are still trying to grow this plant from cuttings, then take a soft or semi-hardwood stem cutting in summer. Apply a rooting hormone (preferably IBA TALC 8000 PPM). Plant the cutting and maintain a soil temperature of 70°F – 75°F (21°C – 23°C). Rooting will take place in 2-3 months.
All that being said, I would still recommend that instead of propagating this plant, buy a plant from a nursery and train it as a bonsai.
Watering Sims azalea bonsai tree
Sims azalea bonsai should be watered generously during the summer season. Especially when the bonsai is flowering.
Make sure you use soft water. This plant does not like hard (calcium-containing) water. You can use rain water. If you only have access to hard water then mix some distilled water to reduce the hardness.
It is very important that the root ball of an azalea is never allowed to become dry. You will notice that the plant is dropping its leaves if it is too dry. Also avoid over-watering the tree.
During the rest of the year, reduce the watering frequency and keep the soil just moist.
Read watering bonsai tree and indoor bonsai tree care for more details.
Wiring Sims azalea bonsai tree
You can wire train this bonsai after flowering is over. Nevertheless, you should be very careful when wiring the branches because they are very brittle. Careless bending can break the branch.
Read : Detailed guide on How to wire a bonsai. This extensive guide includes all the wiring techniques and Do’s and Dont’s. It will also show you other bonsai training techniques which can be achieved without using wires.
Pruning Sims azalea bonsai tree
When to prune Sims azalea bonsai tree?
How to prune Sims azalea bonsai tree?
Branches of this bonsai can be pruned throughout the year. The green, freshly emerging shoots that grow around the flower buds must be pinched out completely.
After about six leaf pairs have formed, prune back the new shoots to leave one or two leaf pairs (back to the lignified portion of the shoot).
Once the flowering season is over, remove the remaining wilted flowers. Otherwise, the plant will start forming seeds. This energy should be directed towards the formation of new shoots and not seeds.
Prune any new shoots that grow directly on the trunk and in the root area as soon as possible.
Read how to prune a bonsai to know about the right technique of pruning and more about defoliating a bonsai tree.
Repotting Sims azalea bonsai tree
When to repot Sims azalea bonsai tree?
Sims azalea bonsai can be repotted every two to three years after flowering. Perform light root pruning.
Use a free-draining but moisture-retentive bonsai soil mix that is acidic (pH 4.5). You can also use proprietary soil specifically made for azalea plants.
You can also make a bonsai soil mix by mixing loam, sand and peat moss (1:2:4).
Please check out how to repot a bonsai to know everything about repotting and root pruning a bonsai.
Must Read: Bonsai Soil Recipes
Must read : Choosing the right bonsai container
Feeding Sims azalea bonsai tree
After the bonsai has finished flowering, apply liquid fertilizer every 2 weeks until late summer. Also apply a soil acidifier.
You should stop feeding the bonsai during flowering and in winter. The plant will tell you when it needs more nutrition by turning its leaves yellow. Apply half strength liquid fertilizer at that time.
Read more about bonsai fertilizer and its application. This will also give you more details on how to feed flowering bonsai trees.
Diseases and pest of Sims azalea bonsai tree
These plants won’t get infected with pests that often. But occasionally, it can be infected by spider mites, scale insects, aphids, Black vine weevil (feeds on roots), Two-banded Japanese weevil, Azalea mealybugs, Azalea lace bugs, and caterpillars.
Aphids, scale insects, mealy bugs, mites caterpillars etc can be removed manually by hands or a gentle jet of water or application of some alcohol with a cotton ball. If the infestation is very severe, you can apply appropriate insecticides. There are many organic and inorganic solutions. Please click on the link at the bottom of this section to know about all the remedies of bonsai diseases and pests.
For vine weevil you can drench the soil with gamma-HCH.
Please make sure you read our comprehensive guide: How to identify and treat bonsai pests and diseases is a great resource for you to see all the organic and inorganic remedies you can use.
