Types of Azaleas and Their Care

This article explains the different types of azaleas, their characteristics and care, as well as benefits and possible risks.
Types of Azaleas and Their Care

Last update: 10 March, 2023

Although they may look similar at first glance, there are many different types of azaleas. This has to do not only with the color of the flower, but with other characteristics, which we will tell you more about in this article.

Also, certain things should be taken into account so that your plants are always healthy and beautiful. Read on and we will tell you more!

The characteristics of azaleas

In Greek, the original meaning of the word azalea is “dry” or “arid”, which referred to the type of soil in which it can grow. On the other hand, its scientific name is Rhododendron simsii.

In particular, it belongs to the Ericaceae family, along with heather and arbutus. This is a very large family, with more than 3,000 species.

However, the different varieties of azaleas can be found almost everywhere in the Northern Hemisphere, both in Europe and Asia as well as in North America. They have also adapted to other environments.

As for its characteristics, it’s a medium-sized shrub. It’s slow growing and can reach up to 3 and 4 meters in height, although some varieties do not exceed 50 centimeters. This depends on the site where it is planted and the type of azalea.

The leaves are dark green and about 3 to 5 centimeters long; the underside is scaly and sometimes with spots. In addition, they usually remain on the plant for quite a long time, falling off only in winter.

Flowering occurs in spring. The flowers are undoubtedly the most striking. They are bell-shaped or funnel-shaped. Their colors vary from white to red, passing through different pinks. There are also yellow and orange ones.

Due to the fact that hybridization has been made with this plant, some varieties have been obtained in which the flowers are so abundant that they completely cover the leaves. For this reason, it’s cultivated for ornamental purposes, being one of the most used decorative plants, both in gardens and indoors.

It can be planted directly in the ground or in pots and developings well in both cases.

Types of azaleas

There are many types of azaleas, including cultivable varieties and different species. These have been classified into two major groups: Tsutsusi (native to Asia) and Penthanthera (from Europe and America).

1. Rhododendron calendulaceum

This is a typical species of the Appalachians, a mountain range on the east coast of the United States, which reaches a part of Canada. It can grow more than 3 meters.

It’s characterized by very showy orange and red flowers. However, a variety has been identified in Virginia that has white flowers with shades of pale pink or yellow edges, according to research.

Rhododendron calendulaceum.
Rhododendron calendulaceum.

2. Rhododendron canadense

This species is also from northern America, specifically Canada, as its name implies. It is a shrub that’s a little smaller than the previous one, since its maximum height is 120 centimeters. The flowers of this type of azalea are pink and appear as soon as spring begins.

3. Rhododendron canescens

This vareity is common in the southeastern United States. It’s also called mountain azalea.

It’s deciduous (its leaves fall off at maturity). Furthermore, it can reach 1.5 to 3 meters. Its flowers are pink, rarely white; and have very protruding pistils.

4. Rhododendron periclymenoides

Known as pink azalea or pinxter flower. It’s also from the eastern United States, extending from Alabama to New Hampshire. Its height can vary between one and two meters. It usually thrives in dry sites.

5. Rhododendron viscosum

This is known as swamp azalea because, unlike the previous one, it tolerates wet sites. However, it must have drainage so that stagnant water does not rot the roots.

It’s also a shade-loving species. It can reach up to two and a half meters and flowers in the early summer.

6. Rhododendron farrerae

Now we will take a look at some types of azalea from the Asian continent. We’ll start with Rhododendron farrerae, which is native to China.

This variety is also deciduous, but it’s quite short: it reaches no more than 60 centimeters. Despite this, its flowers are large and a blend between pink and lilac.

7. Rhododendron japonicum

The Rhododendron japonicum or pink azalea, or Japanese azalea, is a shrub between one to two meters tall that’s native of that country. The flowers, a few centimeters in diameter, are usually pink; in some varieties, it reaches a red or magenta tone, which makes the flowers very attractive.

Rhododendron japonicum.
Rhododendron japonicum.

8. Rhododendron luteum

Among the different types of azaleas are the European varieties. Such is the case of Rhododendron luteum, from the southwest of the continent, although it’s also found in Asia. It’s quite tall, reaching up to four meters. The flowers are yellow .

9. Rhododendron pleasant white

This is a small plant with white flowers and evergreen or dark green leaves, which produces a vivid contrast. It adapts well to gardens and prefers shade.

10. Azalea rosebud

This variety was first produced in 1934 from the Japanese kurume azalea. It has the particularity of presenting double flowers that are similar to rose buds.

It grows very slowly, but it reaches up to 120 centimeters. It doesn’t need much sun and blooms in the spring.

Caring for the different types of azaleas

If well cared for, these plants bloom for quite a long time. Some varieties live up to seven years; others can live up to 25 years.

However, this will depend on the climate, the types of azaleas, and the care you take. Let’s see what you need to take into account.

Planting

Azaleas reproduce by cuttings . They should be about 15 centimeters long.

Before planting, leave them in water for a while until the rootlets appear. Then place them in the soil at a depth of 2 to 4 centimeters.

You can plant most species in the garden or in pots, preferably clay, if they are going to be indoors. The best time to grow them is in the autumn or spring.

Important: always leave a space of at least two meters between each plant.[/atomik-in-text]

The best soil and fertilizer for azaleas

A somewhat acid soil is good for azaleas. Peat and perlite can also be used.

However, do not compact the soil too much so that the water can circulate and doesn’t stagnate. If you’re fertilizing them, it’s best not to cover the root of the plant completely.

Location

Most types of azaleas need a little sun, but not too much. If you grow them outdoors, take this into account and don’t place them where the light comes in during the midday hours.

Temperature

Whatever the location, keep in mind that they are plants that suffer from the heat. Therefore, you must ensure good air circulation. Furthermore, be careful with frost.

Watering

Under normal conditions, especially in flowering periods, they need moderate watering, every other day or every three days. You can increase the frequency in summer.

Water at the root, not on the leaves or flowers. Water should be abundant, but you must ensure good drainage so that it does not accumulate. Preferably, use rainwater or filtered water.

Fungi in azaleas

Protect them from possible parasites. It’s possible that some may develop fungi that affect the leaves, such as powdery rhododendron mildew (Microsphaera azaleae).

You can prevent this by keeping enough space between plants for good circulation, controlling humidity below 50%, and placing the plant in the light. Also, you can flush the leaves with alkaline water (pH 8 to 8.2), which helps to make them uninhabitable for spores.

Agua alcalina para los distintos tipos de azaleas.
Alkaline water protects azaleas from colonization by pests.

The benefits and risks of different types of azaleas

There are many types of azaleas, you have seen. They have certain characteristics in common: they’re all aromatic plants that help purify the air. In this sense, they fight bad odors and can even neutralize the smell of cigarettes.

Also, because they have such colorful flowers, people use them in decoration, giving a touch of color to different environments. Therefore, some say they fill the environment with positive energy.

Moreover, it’s noteworthy that recent studies indicate that the luteum variant is a rich source of flavonoids, essential oils, and steroids. Thus, it may have antioxidant, anti-inflammatory, antiviral, and antibacterial properties.

However, eating it can be toxic. Thus, make sure to keep these plants away from children and pets, as they can even affect dogs and cats, according to research.

There are also reports of cases of adults with intoxication from eating azalea flowers, presenting symptoms such as dizziness, nausea, abdominal discomfort, hypotension, and bradycardia, due to the action of the grayanotoxins of the plant.

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The contents of this publication are for informational purposes only. At no time can they serve to facilitate or replace the diagnoses, treatments, or recommendations of a professional. Consult with your trusted specialist if you have any doubts and seek their approval before beginning any procedure.