Azaleas & Rhododendrons

Increase your understanding of azaleas, rhododendrons, and their cultivars

Actually, azaleas and rhododendrons belong to the same botanical family (i.e. genus Rhododendron). Several tiny growing shrubs from the species Rhododendron go by the popular name “azalea.” Azaleas often have smaller leaves and are generally shorter in height.

Anybody who works in the horticulture sector has to have a basic understanding of plants.

Knowing more about plant identification and cultivation gives you an edge over your coworkers. The horticulture sector is full with specialised firms that draw ardent and often obsessive plant lovers. These plant aficionados are catered to by nurseries and plant specialists, who provide their plants through nurseries, breed new varieties, and design specialised gardens.

You might enrol in this course because rhododendrons are your hobby, or you might just want to increase your general plant knowledge. Despite the motivation, taking this course may be a very gratifying and pleasurable experience for anyone concerned in horticulture, whether they are professionals or just hobbyists.

The Ericaceae family comprises several plants. For a quick introduction to their family, watch this video.

Whom This Course May Benefit

• Nurserymen
• Landscape Professionals
• Gardeners and Horticulturists
• Plant Breeders
• Amateurs, tradesmen and professionals

Lesson Structure

There are 8 lessons in this course:

1. Introduction
   • Introducing Rhododendrons
   • Introducing Azaleas
   • Indica and kurume hybrids
   • Deciduous mollis hybrids
   • Review of the system of plant identification
   • Classification of Azaleas and Rhododendrons-sub genera
   • Information and networking
   • contacts (i.e.: nurseries, seed, clubs etc.)
2. Culture
   • Soils for Azaleas and Rhododendrons
   • Most Common pest and disease problems with Azaleas and Rhododendrons
   • Other cultural considerations
3. Propagation
   • Methods of propagating azaleas and rhododendrons
   • Using root stimulating auxins
   • Propagation of different types
   • Layering, cuttings, seed
4. The most Commonly Grown Varieties.
   • R. arborescens -a very popular species
   • Indica hybrids
   • Kurume hybrids
   • Mollis hybrids
   • Other deciduous hybrids
   • Azaleodendrons
   • Uses for Azaleas
5. Other important groups.
   • Scope
   • Rock Rhododendrons
   • Vireyas
   • Other tropical Rhododendrons
   • Hybrids
   • Cultivated Rhododendron species
6. Lesser Grown Varieties.
   • Obscure species
   • Varieties that have become less popular
   • Alpine Roses R. hirstulum, or R. ferrugineum)
   • Yak Hybrids
   • Lesser grown Azaleas
7. Making the best use of these plants.
   • In containers
   • In the ground
   • Indoor plants
   • Growing and showing
   • Growing for profit.
8. Special Assignment
   • A study of one selected plant or group.

Each lesson culminates in an assignment which is submitted to the school, marked by the school’s tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

• Describe the classification of azaleas and rhododendrons.
• Explain the basic cultural needs that all Rhododendron species share.
• choosing the right materials for propagation
• propagate rhododendrons and azaleas.
• What azalea species are grown most frequently?
• Describe a number of popular Rhododendron types.
• Perform reliable research on lesser-known azalea and rhododendron variants.
• Find out how to use rhododendrons in different ways in your backyard garden.
• Show off your knowledge of a certain Rhododendron plant species or plant species in general.

How to Grow Rhododendrons: Some Suggestions

Rhododendrons may be found all over the world, therefore it is not surprising that there are many different species with unique habits, sizes, and flowering characteristics. Species can also be found naturally in North America, South East Asia, New Guinea, Australia, Korea, Japan, and portions of Europe, although the majority of species are found in China and the Himalayas.

The tropical species from Northern Australia and New Guinea typically flower all year long with a blooming burst in the fall. These plants have only recently gained popularity and are now often regarded as collectibles. On the other hand, temperate climate species that only bloom in the late winter to early summer have long been sought for.

The size and colour of flowers vary greatly between species, ranging from tiny single-colored flowers to large, multicoloured flowers with speckles and variations in the neck. Nonetheless, the overall shape or appearance of the leaves and flowers tends to be similar and makes the rhododendron genus easy to identify.

Several tropical plants grow as epiphytes, like orchids, high in trees. Climate undoubtedly has a significant impact on the kind of plants that horticulturists and home gardeners can choose from. Less hardy plants may need to be kept as greenhouse specimens in lower areas since they are difficult to grow in open ground. The extreme heat of tropical and subtropical climates will also be difficult for certain kinds native to temperate climes.

Phytophthora, a fungus that lives in soil, has been a problem for many people who plant rhododendrons. Wilt and root rot are symptoms of a disease it causes in the plant. Where there is a lot of heat and moisture in the soil, the illness is more common. Certain Rhododendron species and hybrids do, however, exhibit moderate to high degrees of disease resistance.

A Quick Histories

R. hirsutum or R. ferrugineum, sometimes known as “Alpine Roses,” were originally cultivated in the middle of the sixteenth century. Rhododendron was given its genus designation by Linnaeus a century later. Before George Don determined that the two plants were sufficiently similar to belong to separate genera in the 19th century, azaleas were categorised as a separate genus. Thereafter they were combined under the genus Rhododendron.

Three groups make up the Rhododendron genus. Those in the first and second groupings are referred to as rhododendrons. The azaleas make up the third group.

• The first category is further broken down into two subcategories: leaves with and without scales. Scales cover lepidotes. These tiny, evergreen plants have scaly stems and leaves. Elepidotes are huge plants, some of which are trees, without scales, with smooth leaves and stalks.
• The evergreen Vireya, commonly referred to as Malesian rhododendrons, make up the second group.
• They grow in South East Asian tropical regions and have scales.
• The azaleas, which can be either small, evergreen or deciduous plants with tiny leaves, make up the third category.

In general, breeding between the aforementioned three groups is not permitted. Nonetheless, hybridization between species within each group happens often.

In addition to the roughly 800 species currently recognised, there are several hybrids being grown as well as many that are no longer widely practised. For the purpose of making it simpler to identify the ancestry of the various plants, these hybrids are frequently combined into what is known as a “alliance.” An alliance is a collection of related rhododendrons that produce seedlings that resemble their parents. The R. kiusianum partnership, for instance. While hybrids typically differ significantly in the blooms, they typically have the same growth and leaf traits as the original plant.

Many of the natural species of rhododendrons are among those that have suffered since there are so many hybrids available that may boast greater hardiness, larger and longer-lasting flowers, and a variety of sizes to suit all settings. It’s unfortunate since a lot of them are genuinely beautiful plants. Only the most resilient people seem to have withstood the changes in fashion.

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