The fragrant blossoms of the royal azalea attract butterflies, hummingbirds, and bees. In South Korea, it is frequently used as a local symbol. Baron von Schlippenbach, a Russian commander who collected the species in 1854, inspired its species name, “schlippenbachii”.
I. Appearance and Characteristics
Rhododendron schlippenbachii, the royal azalea, is a species of Rhododendron native to the Korean Peninsula and adjacent regions of Northeast China, Japan, and the Russian Far East. It is the dominant understory shrub in many Korean hillside forests, growing at 400–1,500 m (1,300–4,900 ft) altitude.
It is a dense deciduous shrub growing to 4.5 m (15 ft) in height, but more commonly 1–2 m (3.3–6.6 ft) tall. The leaves are obovate, 4.5 cm (1.8 in) long and 2.5–4.5 cm (0.98–1.77 in) broad, with scattered glandular hairs. The flowers are white to pink, often with small red spots on the upper three petals; they are produced in late spring to early summer.
The scientific name schlippenbachii is derived from Baron von Schlippenbach, a Russian officer who collected the species in 1854.
In Korea, it is called 철쭉, cheoljjuk and if the color of the petals is white, the flower is called 흰철쭉, huincheoljjuk. The Royal Azalea is commonly chosen as a local symbol in South Korea, by provinces, cities and counties such as Gangwon Province, Gapyeong and Miryang.
It is widely cultivated in many parts of the world; some cultivars bear white flowers. The fruit is egg-shaped and oval, 1.5 cm (0.59 in) long, with glandular hair, which ripen in October. Azaleas are poisonous and can not be eaten.
II. How to Grow and Care
Sunlight
Royal azalea likes environments with partial shade and can be planted in places that are partially covered with shades. They can also grow in plentiful sunlight, but they need to be protected from intense sun exposure. It is recommended to shade off 75% of the sunlight in spring to prevent new leaves from becoming sunburnt.
Temperature
Royal azalea does not like to be too cold or too hot. It is suited to grow in an environment with a temperature of 12 to 25 ℃. When the temperature exceeds 30 ℃ or is lower than 5 ℃, the plants grow slowly and will enter dormancy. When the temperature is lower than 3 ℃, royal azalea will suffer frost damage. They need a sufficient amount of slightly acidic water. They cannot sustain too much accumulated water.
Watering
Originating from the temperate regions, royal azalea is accustomed to moderate moisture levels and can tolerate brief periods of dryness. This species thrives with a balance between hydration and drainage, exhibiting resilience in fluctuating water conditions. Watering should be adjusted to once every 1-2 weeks, ensuring the soil remains moist but not waterlogged. Typically grown outdoors due to its preference for natural light cycles and climate zones, royal azalea demonstrates a robust growth cycle when provided with adequate rainfall or supplemental watering during its active growing season.
Soil
Royal azalea enjoys rich, loose, and slightly acidic soil. Because the plants do not like too much accumulated water, the soil must be well-drained. Leaf mold, pine needle mulch, peat soil, or fully decomposed groundwood are good choices. These are all acidic culture mediums with strong draining ability. Alkalic or sticky soil cannot be used.
These plants are suited to soil with a pH of 4.5-6. Before planting, it is best to test the pH level of your soil. If it is slightly alkalic, you can moderately add an acidic fertilizer like aluminum sulfate. Mix it with the original soil, and ensure the soil is within the suitable pH range before planting royal azalea.
Fertilizing
To promote healthy growth and vibrant blooms, it is important to provide adequate nutrition to your Rhododendron Schlippenbachii. You can feed the plant with a fertilizer specifically formulated for acid-loving varieties. Apply the fertilizer according to the package instructions, ensuring it is evenly distributed around the plant’s root zone. Additionally, incorporating organic matter into the soil, such as compost or peat moss, can provide beneficial nutrients to support the plant’s overall health. Regular feeding throughout the growing season will help to maintain the plant’s vigor and enhance its beauty.
Planting Instructions
Royal azalea is suited for planting in spring or fall. As a shrub, it takes a long time for the seeds to grow. Therefore, it is best to purchase seedlings or potted plants. If they are planted in the garden, make sure the distance between plants is 61 cm. Dig a planting pit with a diameter of three times that of the root ball of the royal azalea. The roots cannot be buried too deeply, and the root crown should be level with the ground. When the planting pit is half-filled with soil, water it once. When filling is completed, water it again.
Pruning and Maintenance
Pruning and regular maintenance are essential for keeping your Rhododendron Schlippenbachii in optimal health and shape. Proper pruning helps remove dead branches, promotes bushier growth, and encourages more flowers. It is recommended to prune the plant after it has bloomed. When pruning, make sure to cut just above a leaf bud at a slight angle to encourage new growth.
Mulching
Mulching is an important part of maintaining the health of your Rhododendron Schlippenbachii. By applying a layer of mulch around the base of the plant, you can provide several benefits. Mulching helps retain moisture in the soil, stabilizes soil temperatures, and suppresses weed growth around the plant. It also protects the delicate root system from extreme temperatures.
When mulching, use materials like wood chips, bark, or pine needles. Apply the mulch in a layer that is a few inches thick, but make sure to keep it a few inches away from the plant’s trunk to prevent excessive moisture retention, which can lead to decay. Mulching should be done in the early spring or late fall, before the temperatures drop too low.
Propagation
Belonging to a large genus of woody plants known for vibrant flowers, royal azalea is a striking species valued for its ornamental appeal. Its propagation is effectively achieved through cuttings, with a focus on utilizing semi-hardwood segments harvested from the current year’s growth. Care should be taken to maintain adequate moisture and warmth to encourage rooting, ideally using a rooting hormone and a well-draining medium. With patience and proper handling, royal azalea can be successfully propagated ensuring the continuity of its majestic blooms for enthusiasts to enjoy.
Transplanting
The ideal time for transplanting royal azalea is during seasons S3-S5, equivalently ‘late fall to early spring’, as it is dormant and best resists the shock of moving. Choose a location with well-draining soil and partial shade. Remember, the friendly advice – water thoroughly after transplanting and maintain regular watering thereafter.
Pests and Diseases
Rhododendron Schlippenbachii is a beautiful plant that adds charm and color to any garden. However, it is important to protect this plant from pests and diseases to ensure its longevity and well-being. Rhododendrons are susceptible to various pests and diseases that can inhibit their growth and compromise their beauty.
Common pests that can affect Rhododendron Schlippenbachii include aphids, borers, lacebugs, mealybugs, mites, nematodes, scale, thrips, and whiteflies. These pests can cause damage to the leaves, stems, and flowers of the plant, leading to deformities and reduced vigor. In addition to pests, Rhododendrons can also fall victim to diseases such as canker, crown rot, root rot, leaf spot, rust, and powdery mildew.
To prevent and manage pests and diseases, it is crucial to create a favorable environment for your Rhododendron Schlippenbachii. Good gardening practices play a significant role in maintaining the health of the plant. Here are some tips to help protect your Rhododendron Schlippenbachii:
- Clean up fallen leaves and debris around the plant regularly. This will reduce the likelihood of pests and diseases finding shelter and spreading.
- Promote good air circulation by pruning and thinning out branches and foliage. This will help prevent the development of moisture-loving diseases.
- Avoid overwatering, as excessive moisture can create favorable conditions for pests and diseases. Water the plant only when the soil feels dry to the touch.
If you notice signs of pest infestation or disease on your Rhododendron Schlippenbachii, taking prompt action is essential. Depending on the severity of the problem, you can use appropriate organic or chemical treatments to control the pests or diseases and protect your plant.
III. Uses and Benefits
The Rhododendron Schlippenbachii is a stunning shrub with unique characteristics that make it a beautiful addition to any garden. Its vibrant flowers and colorful leaves add a touch of elegance and charm, making it a popular choice among gardening enthusiasts.
IV. Harvesting and Storage
Collect the flowers of royal azalea for cut flowers, focusing on ones that have not yet fully bloomed. These flowers are both more beautiful and can be enjoyed for a longer period of time. Use a sharp knife to cut the bottom of the branch diagonally; this increases the area where the cut flower can absorb water. To extend bottle life, do not let the flowers receive direct sunlight. Change the water frequently and cut the bottom of the cut flower obliquely when changing water.
