Japanese Azalea (Rhododendron japonicum) – Care Guide

It is one of the favorite flowering plants for interiors, with its wide range of colors bringing a note of cheer to our homes. It is the Japanese Azalea, a small evergreen heath shrub that grows with a bushy habit. In this article, let´s review How to grow Japanese Azalea and Propagate from seeds and cuttings. Also, we will review the properties and benefits of the Azale Japonica (Rhododendron japonicum).

Its peculiarity is the massive flowering characterized by very beautiful flowers ranging from pink to red, purple, and white. Today, the Japanese Azalea is widely used as a gift plant.

It is characterized by woody branches and leaves that can be double or semi-double, always very abundant. Leaves are leathery, lanceolate-rounded, small, bottle green in color. The width and height reach up to 5 ft (1.50 meters).

Botanical Classification

Let´s review the Botanical Classification of the Japanese azalea plant.

Azalea Japonica is a species of the genus Rhododendron in the family Ericaceae.

Japanese Azalea scientific name: Rhododendron japonicum.

Main Species of Azalea Japonica

Main Species. Among the varieties of Rhododendron japonicum there are ‘Satsuki’ and ‘Kurume’, two hybrids propagated by cuttings.

Rhododendron japonicum Satsuki is a variety called ‘late-blooming’ because it blooms only at the end of spring in the months of May-June (Order here).

The Rhododendron japonicum Kurume variety is a semi-dwarf hybrid that flowers abundantly.

A Louisiana grower, Robert C. ‘Buddy’ Lee developed a Japanese Azalea encore that blooms from spring to fall.

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Brussel's Bonsai Live Satsuki Azalea Outdoor Bonsai Tree-5 Years Old 6' to 8' Tall with Decorative Container, Small
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Brussel's Bonsai Live Satsuki Azalea Outdoor Bonsai Tree-5 Years Old 6" to 8" Tall with Decorative Container, Small
  • Contents: bonsai, decorative container (assorted colors & styles), soil, Care instructions.
  • SPECIES: Of all shrubs with flowers, the Azalea is by far the most dramatic with brilliant blooms of radiant colors blooming in late spring. While there are many species of Azalea, the Satsuki, or Rhododendron indicum is easily one of the most popular, featuring an excellent low, twiggy habit with lovely funnel shaped unscented flowers in whites, pinks, reds and purples.
  • Age/size/Care: your Small 5 Year old bonsai will arrive between 6" To 8" Tall in a 6" Container and will perform Best outdoors (see detailed care instructions in images)
main species azalea japonica
Main Species Azalea Japonica.

Flowering Rhododendron japonicum – When Japanese Azalea Blooms?

When Japanese Azalea Blooms? Rhododendron japonicum generally blooms from early April to mid-June, producing very showy flowers whose color ranges from white to pink, red, and purple.

Cultivation Tips for The Japanese Azalea

Cultivation Tips for The Japanese Azalea. The Azalea Japonica is an ideal plant for the garden, for entrances and driveways, terraces, and also to decorate the house.

How to Grow Japanese Azalea in a Pot

How to Grow Japanese Azalea in a Pot. Azalea Japonica boasts a shallow root system, its small size makes it ideal to be grown in a container on a balcony or terrace.

The pot must be wide enough to contain the plant. Learn more about How to Care for Bonsai Azalea.

Soil for Japanese Azalea in a Pot

The best soil for growing Japanese Azalea in a Pot is a potting mix soil for is for acidophilic plants to keep heath plants.

During the growing season, you should turn the pot every week to spread the growth.

It is best to wait until the end of flowering before repotting.

It is good to consider that flowers are quite demanding in terms of nutrients, which is why you should not risk damaging the fragile root system. All the more so if the pot is tied to the roots.

how to grow japanese azalea in a pot
How to Grow Azalea Japonica in a Pot.

How to Grow Japanese Azalea in the Garden

To Grow Japanese Azalea in the garden, follow these tips. Choose the best location. Azalea Japonica prefers a semi-shaded position to encourage both flowering and survival in the summer months.

Rhododendron japonicum can be grown and cultivated in the outdoor garden year-round throughout. Be sure to protect this azalea during winter. Mulching should be done in winter in areas with a harsh climate. It does not tolerate dry and windy climates well.

Best Soil for Japanese Azalea

Japanese Azalea requires acidic, peaty, fertile, moist, well-drained soil.

Well-drained soil is essential. It must be considered that all acidophilic plants suffer from basic pH soils and the presence of active limestone (Order here).

Japanese Azalea also requires acid soil, with a pH lower than 6.5, porous, light, never clayey, always well-drained, rich in partially decomposed organic matter, without stagnation, fresh. Learn more about How to Measure Soil pH.

Let´s continue reading about How to Grow the Japanese Azalea.

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Temperature

The best temperature to grow Japanese Azalea, before flowering, is 50 and 60 °F (10 and 16 °C). When the first buds appear, the plant should be left in a warmer place (at about 65 °F (18 °C).

Light

Light and Location. The Azalea Japonica should be placed in a bright place, near a window but avoid direct sun. Starting from May it should be moved outdoors, in a cool place.

Do not expose the plant too much to sunlight, but opt for a location that is partially shaded. Resistance to the sun is higher for plants placed in full soil and with soil kept constantly humid. In the open ground, exposure on the north side of the house or in front of a glass door or window with the same orientation is ideal.

Watering

Watering. The Japanese Azalea requires frequent watering, especially in spring and summer. The shallower roots of the Japanese Azalea are the most thirsty.

To water Japanese Azalea, soft water or rainwater should be used, as this plant does not tolerate lime. It is necessary to keep the soil moist by avoiding the root ball to dry out, but also by avoiding water stagnation. During summer, the Japanese Azalea needs daily watering.

During the cooler months, three watering per week is sufficient. After a couple of years, the plant will be satisfied with rainwater, except in the case of prolonged dry periods or heat waves.

To reduce the frequency of watering, you can mulch the base of your Azalea Japonica with maritime pine bark. This will retain moisture and cool the soil.

How to Propagate Japanese Azalea

Let’s review the different ways to propagate Japanese Azalea.

How to Propagate Japanese Azalea. The Azalea Japonica can be propagated by seeds, to improve the characteristics of the varieties. However, propagating Azalea by cuttings is the best way to propagate the Japanese Azalea and the most used. From all the methods, we recommend propagating the Azalea Japonica from cuttings.

The best time for taking azalea shoots for propagation is from July to September. The cuttings must have a length of about 4” (10 cm), they must be cut obliquely in the part under the node from a strong and healthy mother plant, then the lower leaves will be removed.

The cuttings are then placed in a container filled with peat and perlite, cover the container with plastic, and place in a semi-shaded position at a temperature of about 68 °F (20 °C). Finally, and you wait for the rooting process.

The soil should always be kept at the right humidity. Generally, the rooting of azaleas takes place after about thirty days, the roots will be a bit weak, so it is necessary to pay attention at the time of repotting to perform the maneuvers gently and delicately. Pots should have a diameter of about 3” (8 cm) and should contain peat, leaves, or pine needles and clayey or sandy soil. As soon as it is noticed the appearance of buds in the plants, it is necessary to remove them and a little topping operation must be done to ensure a correct and aesthetical development of the plant. With the growth of the seedlings, which takes place after about two-three months, the plants will have to be repotted in bigger containers. Learn more about How to Propagate Azalea Step by Step.

how to propagate japanese azalea

Fertilizing Japanese Azalea

How to Fertilize Japanese Azalea. If you want to keep the plant for the next season, you must fertilize it after flowering using a specific fertilizer, rich in potassium, that will also ensure spectacular flowering (Order here).

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How to Prune Japanese Azalea

How to Prune Japanese Azalea. Rhododendron japonicum does not need to be pruned. Pruning is useful if you want to balance the shape or reduce the size of the plant. In this case, you should wait until the flowering is over and prefer a light and delicate pruning rather than a drastic cut.

It is necessary to regularly remove withered flowers to stimulate the appearance of new buds.

how tu prune azalea japonica

Combinations With Other Plants

Japanese Azalea can be combined with other acidophilic plants such as Enkianthus, Leucothoe, Kalmie, Camellia, Rhododendron.

Other Care Tips Azalea Japonica

Other Care Tips, Azalea Japonica. When in bloom, Rhododendron japonicum needs environmental humidity to keep the buds from turning brown, as dryness prevents them from opening. Yellowed leaves are a symptom of an excess of lime in the water or a lack of nutrients. The plant blooms better if the roots are tight, in a small pot.

This plant has long been cultivated as a bonsai under its more specific varieties ‘Satsuki’ and ‘Kurume’. If you want to try growing bonsai on your own you must use a rather acidic soil, like heath plants, and water enough so that the soil remains moist but never wet. Organic fertilizer for azaleas is used, but only during the growth phase, and prune the Azalea Japonica bonsai just after flowering. You can shape it with wire, proceeding with caution because the branches break easily. The bonsai should be repotted very carefully every two years.

Pests, Diseases, and Other Adversities

Pests, Diseases, and Other Adversities. The plant can be attacked by the red spider mite. Another enemy of the plant is root rot. Learn more about How to Mix Neem Oil for Plants.

Curiosity About Azalea Japonica

Azalea is part of the plants that purify the air inside the house, it can remove formaldehyde and ammonia from the air of closed environments. 

Toxicity and/or Herbal Use of Azalea

Benefits of Rhododendron japonicum. A characteristic of many species of azalea is to have flowers that produce particularly poisonous nectar. Many azaleas boast antiseptic properties and are useful in combating rheumatism.

On the other hand, Azalea Japonica is toxic to cats, according to the ASPCA.

“Please note: Pharmaceutical applications are listed for informational purposes only. They must be recommended and prescribed by your physician.”

toxicity japanese azalea
About Henry Morgan

We are the Morgan family, Henry, and Julia, both agronomists from the University of Michigan, where we met. We are experts in putting our hands in the soil and developing organic foods and improving production processes for decades. Likewise, we have worked for companies such as Mondelez International, BASF, Monsanto, etc. currently in our role as science writers for TheGardenStyle.com as well as advisors in promoting large scale food growing in urbanized areas. In this website, we share what we are most passionate about, gardening and farming. Enjoy and see real photos on our website.