Azalea forms part of the Rhododendron genus that contains around 1000 tree species.
Of all these species, Satsuki azalea (Rhododendron indicum), Kurume azalea (Rhododendron kiusianum x R. obtusum), and Kaempferi Azaleas (Rhododendron kaempferi) are most commonly used as bonsai.
Azalea bonsai are very popular thanks to their spectacular flowers. If you care for this plant correctly, you should see it blooming in late spring to early summer.
These flowers come in many different shapes, sizes, and colors that depend on the cultivar of Azalea you have.
Satsuki and Kurume azalea cultivars are evergreen which makes them ideal bonsai specimens.
Of all azalea cultivars, Satsuki is the most popular variety followed by Kurume. This is due to their ability to adapt well to container living, heavy pruning, and their spectacular flowers.
These little trees also form substantial trunks in a very short amount of time adding to their popularity.
Care Guidelines For Azalea Bonsai
Ideal Placement
Azaleas prefer outdoor conditions in areas with semi-shade. It is best to grow it in conditions as close to its natural habitat as possible for optimal growth. Azalea naturally grows in environments that are protected by tree canopies in woodland areas.
This little tree naturally has shallow roots that are easily damaged if placed in a too hot, sunny spot. Too much sun will also ruin the flowers. Keep your bonsai in an area with light shade for the best results.
It is also best to protect this tree against frost and extremely cold winter conditions. You can usually keep this tree outside until the temperature drops to around 45 degrees Fahrenheit (7°C). Once the temperature drops below this threshold, it is best to take your little tree inside.
Make sure the inside location is still fairly cold to allow your tree to become dormant. Temperatures between 35° to 55° Fahrenheit (2°-13°C) is ideal for this purpose as long as your tree won’t be exposed to frost and cold drafts.
Once dormant, you can mulch up the rim of the pot to protect the roots.
Also, make sure to protect your bonsai against rabbits and rodents. They find the bark of azaleas particularly tasty and will seek it out in the winter months when food is scarce.
Water Requirements
Azalea bonsai need a lot of water during the growing season to stay healthy. Never allow the soil to dry out completely. You will quickly notice wilting and other signs of drought stress when an azalea is underwatered regularly. In the winter months, your azalea can be watered less, but do make sure it doesn’t ever dry out completely.
To keep your plant growing optimally, make sure the soil is evenly moist at all times.
It is best to water your bonsai at least once a day throughout the growing season. Keep the soil moist but not soggy for the best results.
If your azalea bonsai was neglected and allowed to dry out your little tree most likely experienced some root death. This can influence growth and recovery time.
Since azalea needs to be watered so frequently, you will need to make sure that the soil drains really well. Your little tree will develop root rot if left to stand in water for long periods of time. When it comes to azaleas, moist is good since it allows the roots to breathe and soggy or saturated is bad since it drowns your plant.
When it comes to azaleas, the water you use is also very important.
If you can, water your little tree with rainwater.
Rainwater has a neutral pH that won’t damage your bonsai. If you don’t have any rainwater, make sure to use lime-free water or water that is slightly acidic.
Azalea prefers slightly acidic soil and lime is alkaline. This may influence the growth and health of your tree negatively if used every day. If you live in an area with lots of lime in the water, make sure to gather rainwater or buy container water from the store.
Lime deposits tend to build up in the soil over time which may kill your little tree.
If you have to use alkaline water, make sure to water your tree with a bit of vinegar every month or mix in a bit more compost into the soil. Organic matter like compost will drop the pH level of the soil and the vinegar will flush out any lime deposits. Mix about 1 tablespoon of vinegar with a gallon of water to avoid damaging your plant.
Soil And Fertilizing
Azalea needs to be fertilized regularly during the growing season. There is special rhododendron or azalea fertilizer available for exactly this purpose. If you can’t get any rhododendron fertilizer, make sure you get fertilizer for acid-loving plants.
Liquid azalea fertilizers should be used weekly since it gets washed out by the regular waterings fairly quickly.
If you go for a solid fertilizer, you can get away with fertilizing every two weeks until your tree starts to flower.
If your tree starts to flower, refrain from fertilizing your plant or only use half the normal dosage. Feeding during blooming will cause your little tree to cease blooming in favor of leave growth. After flowering, feeding your little tree once a month with solid fertilizer or every two weeks with liquid fertilizer should be sufficient until winter starts.
Once winter sets in, you can refrain from fertilizing until the start of spring.
Pruning Times
Azalea bonsai are basally dominant. This means that the lower branches grow stronger than the weaker branches at the top.
For this reason, you will need to prune the branches at the bottom harder than those at the top.
Azalea bonsai do really well when pruned quite heavily, they will even grow new shoots from branches with no leaves left on them. This makes it easy to shape your tree.
The best time to prune your tree is after the blooming cycle ends. Cut away or pinch back any wilted flowers and ovaries that are left. Make sure you leave some newer shoots where you want new branches to grow.
If the center of your tree is bare, prune it back heavily to rejuvenate it.
After pruning, refrain from pruning again until the next blooming cycle unless it’s unavoidable. New flower buds will develop during the summer months for the next blooming cycle. If you prune too late, you will damage and remove these buds resulting in very little to no flowers on your tree.
It is possible to remove any unwanted shoots from the base of the plant however without affecting the blooming of the next season.
Remove all dead flowers at the base of the flower to prevent seed pods from forming. This way you can encourage leave growth after flowering. If you want to enhance the look of your azalea, train any new growth immediately or remove them if unwanted. Secondary shoots can be pruned away midsummer.
If your tree needs some heavy styling, it is best to do it in spring. You will be preventing flowering during this season by doing so, but it will benefit your tree in the long run.
Make sure to make clean cuts with sharp tools and seal large wounds to prevent damaging your little tree.
Propagation Management
Azaleas are mostly propagated by taking cuttings in spring and summer. These trees are very collectible due to budding back easily on old wood. The cuttings taken are usually softwood. Most azalea cultivars root easily as cuttings, but the success rate does vary from one cultivar to another.
If you’ve taken cuttings in summer, it is a good idea to protect them against excessive evaporation by using transparent plastic sheets with a few holes for ventilation.
Potential Pests And Diseases
Azaleas are quite pest-resistant bonzai if kept healthy.
The only time you need to worry is if your little tree is stressed due to lack of water or another problem. Things you need to look out for during this time are spider mites, vine weevil, nematodes, whitefly, scale, aphids, mildew, bud blast, rust, petal blight, and lime induced chlorosis.
Root rot is a common occurrence in azalea planted in poor draining soil. You will also need to look out for a fungal disease that causes leaf galls.
Repotting Times
Azalea, being mostly evergreen, needs repotting every two years to stay healthy. The best time to do this is in spring after your plant stops flowering. You can also do repotting before your plant flowers, but you’ll have to remove the flower buds to prevent putting extra strain on your little tree during the recovery period.
Repotting time is also the best time to do some root maintenance.
Keep in mind that azalea has very few tap roots and relies mostly on a vast network of thin feeder roots. You will need to be very careful not to damage too many of these thing roots while disentangling them.
Azalea can withstand heavy root pruning but you also don’t want to stress your plant unnecessarily.
It is also very important to cut out the bottom of the root ball during each transplanting. This can be done by cutting a cone shape into the bottom of the root ball that extends right up to the trunk. This has to be done to prevent rot due to lack of air as the roots grow very close together in this area which leads to poor drainage.
Azalea requires special lime-free soil. It is very important to add a little more peat to the mix to increase the acidity if you’re making your own mix. Soil that contains equal amounts of humus, pumice, and akadama is a great mix for azaleas.
After repotting, make sure to place your plant in a cool shady area for at least a week to help it recover.
Also, make sure to water the plant thoroughly and prevent blooming in the first year after repotting to lessen the strain on your plant.
Wiring Your Bonsai
Wiring on azaleas is often done in spring after the plant stops flowering. If you want to do heavy styling, it is best done before flowering.
If you go this route, make sure to prevent flowering for that year to reduce stress on your plant.
Keep in mind that azaleas have very brittle wood and bark. So, wiring should be done very carefully with soft, aluminum wires to prevent damage. You can also use plastic tape to protect the bark from damage.
Make sure to be very careful not to break any branches. Bending can easily snap a branch due to how brittle they are. If you need to do a lot of bending, make sure to do it in stages or only bend soft new growth to prevent breaking.
Azaleas are most often trained to look like miniature trees with one distinct trunk.
It can also be grown in the root-over-rock fashion as well as semi-cascade, windswept, slanting, and informal upright styles.
Q. How Often Do Azalea Bonsai Bloom?
A. Azalea bonsai, specifically Satsuki azaleas, will bloom at least once a year, but it is possible for blooms to appear several times a year. This bonsai can usually be seen blooming anywhere between October and June.
If you want to promote blooming, make sure to care for your bonsai properly.
Q. How Often Should You Water An Azalea Bonsai?
A. Azalea bonsai are quite thirsty little trees. They like to be watered frequently. Never let the soil dry out completely, but allow it to dry somewhat between waterings. You can use your finger to determine if watering is necessary. Only water if the soil feels dry to the touch about 1 inch (2.5cm) below the soil surface.
Q. Are Azalea Bonsai Trees Poisonous To Cats?
A. Azalea bonsai can be dangerous to cats. All parts of the plant are poisonous. Symptoms of azalea poisoning include vomiting, excessive drooling, diarrhea, tremors, seizures, lack of appetite, and falling into a coma.
Q. Do Azalea Bonsai Lose Their Leaves?
A. Azaleas used as bonsai are mostly evergreen (stays green throughout winter), but it is possible to find a deciduous (lose their leaves during fall and winter) variety. There are also other causes of dropping leaves such as overwatering, underwatering, lack of sunlight, and unsuitable soil pH.