Rhododendron is a very large genus in which more than 1000 species of woody plants are found. Colorful flowers bloom in clusters on Rhododendron. It is suitable for almost any garden, as some varieties become large trees that can reach up to 100 feet tall; While the smallest variety is only 18 inches long and wide. Their size, texture, design, and color of flowers and leaves depend on which species and cultivar they come from.
Rhododendron belongs to the heath family. They are native to the Himalayan region as well as East Asia and evolved there. But they are also found in other parts of Asia, North America, Europe, and many parts of Australia. But their numbers are less here as compared to their original habitat. Rhododendrons are popular among gardeners because of their evergreen shrubs, early bloomers, and attractive flowers.
Deciduous or evergreen:
Rhododendrons are completely evergreen, but as for azaleas, they can be deciduous or evergreen.
Soil and zone:
Rhododendron likes acidic soil. Although they can be grown in hardiness zones 4 to 9, most of their varieties are found suitable for zones 5 to 8.
They like cool moist climates. Besides, mild temperature conditions are also favorable for them.
Sunlight and shade preference:
This flowering bush is found in its natural habitat in places that are protected from intense sunlight and have dappled shade. This is because it likes partial shade or dappled shade. Plants with large leaves, in particular, perform best in such conditions. On the other hand, small-leafed alpine and dwarf species, which can be either deciduous or evergreen, perform best in cooler areas with bright light.
Types of Rhododendrons:
Their different species are used in different ways. There are many types of rhododendron plants which include trees, shrubs, and vines. You can choose any of these species depending on your choice, need, and role in the garden.
Their flowers grow in groups. The group of these colorful flowers has been named ‘Trus’. They bloom in many different colors. Such as red-violet, lavender-blue, apricot, orange, yellow, pink, white, and dark red.
These generally bloom until mid-spring. While some varieties bloom as early as March and some as late as July.
The size of its importance can be obtained from the list given below;
- It is the national flower of Nepal,
- It is the flower of the US states of Washington and West Virginia.
- Nagaland and Himachal Pradesh which are states of India, Rhododendrons are their state flower.
- And finally the provincial flower of Walshi in China.
Most of the rest of the coast is in bloom from late to early summer. While these flowers are colorful, they are naturally attractive.
About Rhododendrons and Azaleas
Both Rhododendron and Azalea come under the Rhododendron genus. In common parlance, Rhododendron should be considered a large genus within which Rhododendron is placed and Azaleas are also classified. Rhododendrons are generally larger than azaleas. Rhododendrons are completely evergreen, while azaleas can be deciduous or evergreen.
Basic differences between rhododendrons and azaleas
- Size: Rhododendrons are generally large bushy varieties. Some of which are up to 20 feet wide. Azaleas, on the other hand, are generally smaller plants, with some varieties reaching only 1.5 to 2 feet tall.
- Flowers: Rhododendron flowers are usually bell-shaped. About 10 stamens emerge from the center of their flower. The long and thin structures protruding from the center of the flower are called stamens. Whereas the front parts of Azalea flowers are more spread out and funnel-shaped. These have less than 5 stamens.
- Leaves: Rhododendron leaves are large in size and leathery. Additionally, it is somewhat thick and often smooth. Whereas the leaves of azalea are pointed and narrow. Additionally, their leaves have small hairs on the top.
- Climate: Rhododendrons prefer zones 5 to 8, where it’s neither too hot nor too cold. They require a certain amount of coolness to develop their flowers. But they demand a little care in winter. On the other hand, Azaleas are not overly sensitive to climate and thrive in zones 4 to 9. They are seen in cold climates to hot areas. Some of their varieties are evergreen and all the rest are deciduous.
Gardeners select rhododendrons and azaleas according to their wishes and needs. With the help of their many varieties, they enliven almost all scenarios. For this, they take the help of their various colors, shapes, and designs. Rhododendron and azalea flowers come in many colors. Most of their varieties of plants flower in spring. But some varieties bloom in summer.
Design Ideas for Rhododendron
Rhododendrons will undoubtedly help in giving a great look to your garden. But to choose it and get the most out of it, you should pay attention to some of the ideas given below.
- When selecting and purchasing rhododendrons or azaleas, you should pay attention to when they flower. As mentioned, most of their varieties bloom in mid-spring. While some varieties bloom in early March and some in late July.
- You can choose different varieties, which have different blooming times. In this way, you can keep your garden colorful for a longer period.
- These can be used in many ways. You can plant them in foundation plantings, hedging, screening, container gardening, mixed borders, or mass plantings. Planting small plants (bushes) and big bushes and trees at appropriate places enhances the beauty of the garden for a long time.
- Since these are acid-loving plants and trees, they can be planted with other acid-loving plants and trees, such as ferns and flowering dogwoods.
- Generally, it is advised to plant them in such a place where they do not have to compete with other plants for water and nutrients and they keep growing easily. But it is not that all other plants are its enemies. There are some flowers like lily-of-the-valley, tulips, and daffodils which can be planted with rhododendron or azalea. They do not compete with each other and bloom almost at the same time. In this way, the entire area becomes mesmerizing with the presence of flowers.
- If you live in an area where spring temperatures exceed 90°F, avoid choosing a white-flowered azalea. As the heat increases, the thin petals of their flowers fall off, due to which them look less beautiful. Also, some small plants in such areas struggle due to the heat.
Important tips before planting
It is important to keep these important things in mind before or at the time of planting.
- Rhododendron varieties that have larger leaves require dappled shade. This is especially important in warm areas of zones 7 to 11. Keep this in mind while choosing the planting location, so that you do not have to face problems in the future. Apart from this, it is also important to protect them from deep shade or full sun. For this, it would be best that you choose a place where there is sunlight but there is also a few hours of shade.
- The soil should be well drained. It should also be humus-rich, moist, and acidic with a pH of 4.5-6.
- Rhododendrons and azaleas have shallow root systems, so they require moist soil. Therefore, to prevent them from drying out, one must keep the soil constantly moist. Some of their species start giving signals as soon as they suffer from drought. Using mulch would be a good option.
- After testing the soil, amend the area with compost, peat moss, or another alternative if the soil appears poor.
- Zones 3 to 6, known as cold or temperate zones, have few problems due to the cold. Like less or no growth of flowers and problems of fungus. To prevent this from happening, you can plant them at a place where they get at least 6 hours of full sun.
- In these areas, their leaves and buds dry up due to winter winds and may even die if not taken care of. Therefore, provides them protection from cold winds.
- When mixed with concrete, their roots make the soil alkaline, which ultimately proves harmful for them. Therefore avoid planting them near concrete.
- Avoid planting rhododendrons with ground plants that compete with them for space, water, and nutrients. We have mentioned above about the plants and flowers to sow with them.
How to plant rhododendrons and azaleas? (Planting Tips)
- Plant plants according to the climate of your area. When to plant is described below.
- Plants have to be planted at some distance from each other. For this, you can plant them at a distance of 2 to 6 feet based on their estimated mature size.
- Dig a pit for planting whose depth should be equal to the root ball, but the width should be almost double. Water well before planting.
- After putting the root ball in the pit, fill the pit half with soil. Then add water before filling the remaining soil. This will settle the soil and provide adequate moisture for the plant.
- It would be better if the upper roots of the plant were kept at soil level or a few inches higher. If you plant them too deeply, waterlogging may cause the roots and stems to rot.
When to plant
When to plant Rhododendron is mainly determined by the climate of your area. For this, planting at the following time is recommended:
Mild climate: In such climates, you can plant at any time throughout the year, whenever the soil is workable.
Cool Climate: The best planting time in this climate is early spring. As an alternative, you can also plant in early autumn.
Warm climates: In warm areas, it is best to plant in the cooler months to help the plant’s root system become established. In such areas, planting in the fall is recommended.
How to care for rhododendrons and azaleas?
- Due to the lack of water in rhododendrons, the formation of flower buds reduces. Therefore it is important to maintain moisture in the soil. To conserve soil moisture and protect their shallow roots, mulch the plants with 3 to 5 inches of pine bark chips or pine needles each spring. You can also check its quality any time before the year is over; If necessary, they can be changed even before time.
- While mulching, keep in mind that plants like moisture, not waterlogging or too wet. So avoid piling heavy mulch around the trunk of the shrub. Otherwise, the soil as well as the stem of the plant may remain excessively wet, which will cause rot. Leave a few inches of space around the stem free of mulch for protection.
- The roots of azaleas and rhododendrons are shallow, due to which there is a risk of their burning due to excessive use of fertilizer. For these, it is advised to use fertilizer carefully. Keep in mind that they need to be fertilized only when the flower buds swell in early spring. Apart from this, they do not need fertilizer.
- If you are not benefiting from their seed production and want to encourage continued growth, deadhead after flowering. You need to be careful when deadheading. Because the next year’s buds are located just below the ends of the old wood, they begin to develop immediately after flowering.
- Due to its shallow roots, the process of transplanting becomes quite easy. Transplants are most successful when plants are dormant and the environment is cool, such as during fall or early spring. But you are free to transplant rhododendrons and azaleas at any time of the year.
Diseases and pests
Rhododendrons are beautiful, but they also have some problems. Which come in the form of pests and diseases. Take better care of them to protect them from diseases. At the same time, some of these pests and diseases are very minor and some are fatal. It is necessary to identify and resolve them at the right time. Here are the pests and diseases to which rhododendrons are susceptible:
- Branch die-back
- Phytophthora and Armillaria root rot
- Powdery mildew
- Petal blight
- Rhododendron borer
- Azalea caterpillar
- Spider mites
- Leaf miner
- Vine weevil
- Leaf hoppers
- Lace bugs
- Scale insects
Recommended Varieties of rhododendrons and azaleas
There are a large number of species in the Rhododendron genus. All of them are different from each other in some way or the other. It is probably not possible to tell about them all in this space. On the other hand, even if we give you examples or suggestions of some varieties, you may not be able to use this plant as well as you could.
All of you readers may live in different regions and different climates, which means that a plant that is suitable for one may not be suitable for someone else. In this way, our appreciating some varieties will prove to be less useful for some people, which is not right to do.
Therefore, we humbly request all of you to spare a little trouble and visit the official website of the American Rhododendron Society. At this place, you will find many shrubs including Rhododendrons, and Azaleas under ‘Plant Data’. Also here you can choose your favorite plants through categories like “A to Z” Names List and Good Performers.