Overview

Azaleas are vibrant and versatile flowering shrubs that are close relatives of rhododendrons. Available as evergreen or deciduous plants, the true brilliance of azaleas is fully revealed in the spring. Even just one azalea can create a dazzling floral display. This article will cover every aspect of caring for azaleas.

Family

Family: Ericaceae Genus: Rhododendron Subgenera: Azaleastrum Azaleas were considered a separate species to rhododendrons until approximately 2005 when botanists decided that the two species were similar enough to be grouped together.Rhododendrons are a large group of 1,024 woody shrubs.

What are Azaleas?

Similar to rhododendrons, azaleas are a large group of evergreen or deciduous flowering shrubs. These shrubs thrive best in shadier locations and their vibrant blooms can last for a couple of months in ideal conditions. Azaleas grow fairly slowly and are considerably self-sufficient plants. They are quite easy to cultivate, making them attractive ornamental shrubs for a wide variety of gardens. They also make excellent container plants.

Botanical Characteristics

Classification: Deciduous & evergreen Native to: Asia, North America, Southwestern Europe, Turkey Care Level: Easy to moderate Size: Various Common Problems: Lace bugs, leafy gall, spider mites Toxicity: Extremely toxic to dogs, cats, and people

Where are Azaleas found?

Azaleas are native to a wide range of environments in both hemispheres. Most azaleas are found in parts of Asia including China, Korea, Japan, and Mongolia. The azaleas in these areas tend to be evergreens. Deciduous azaleas are typically found in North and South America along with Turkey, which straddles Southern Europe and Western Asia. Around the world, several prominent azalea festivals are held every year to celebrate these stunning shrubs. The most famous festivals occur in Hong Kong, Japan, and Korea. The United States also hosts azalea festivals, namely those in Alabama, Florida, and North Carolina.

What are the seasons for Azaleas?

Azaleas are highly-prized for their floral displays, which provide various colours including orange, pink, purple, red, and yellow. Most species of azaleas flower during the spring, and these blooms can last for quite a few weeks before dropping off. Deciduous azaleas flower for a longer period than their evergreen cousins, particularly in the United States. These varieties also tend to produce a beautiful fragrance from their flowers. Evergreen azaleas retain their leaves all year round.

How do you identify Azaleas?

Because these two woody shrubs are so similar, it can be difficult to tell azaleas apart from their rhododendron relatives. But a few subtle distinctions can help differentiate them. Rhododendrons tend to have larger leaves than azaleas. The texture is also different as rhododendron foliage is much tougher than the delicate thin leaves of azaleas.  Azalea leaves also sport fine hairs. Azalea stems are more numerous than rhododendrons. Azaleas also produce their tube-shaped blooms in groups of three that protrude from the tip of a stem. Azalea flowers also cover a broader spectrum of colours than rhododendrons. Azalea flowers have five or six stamens as opposed to the ten that rhododendron flowers have.

How to grow Azaleas

Despite their showy appearance while in bloom, azalea shrubs require minimal care. This makes them excellent statement shrubs for less-experienced gardeners. Here is an overview of how to grow azaleas.

Planting

Azaleas are slow growers and generate fairly shallow roots. This makes them ideal as shrubs for containers. Azaleas don’t like to be planted too deep into the soil. Before putting the azalea into the growing medium, enrich the area with some organic matter. This should be fairly acidic – things like pine needles or tree bark that have started breaking down are ideal. When adding the azalea, make sure that the roots lie just underneath the soil. The planting hole should be more wide than deep when compared to the size of the rootball. Fill in around the rootball with some peat-free ericaceous compost and organic matter like leaf mould.

Watering

Azaleas grow best when their soil is kept lightly moist at all times. Collect rainwater to use when watering azaleas because tap water is usually more alkaline than acidic. Humid climates with more rainfall suit azaleas perfectly.

Sunlight

In their indigenous habitat, azaleas typically grow within jungles or woodlands. As such, azaleas prefer shadier planting spots with indirect or dappled sunlight. This also helps to reduce water loss through evaporation. Azaleas appreciate some morning sun, but if they’re left in direct afternoon sunlight, their foliage can become sunburnt. Azaleas also like to have some shelter from strong winds.

Soil Conditions

Azaleas are used to slightly acidic soils, so aim for a pH range of 4.5 to 6.0. Mix a lot of organic matter into the soil to provide enough nutrients. Use acidic growing mediums like ericaceous compost (preferable peat-free). Adding very weak amounts of things like black tea or watered-down coffee grounds can also increase acidity.

Fertiliser

Because azaleas grow quite slowly, they don’t really need fertilising in most cases. Azaleas grown in containers are more likely to need some fertiliser. In this case, refresh the upper layer of compost every so often. A weekly dose of ericaceous fertiliser can also help container azaleas. Some azaleas can suffer in soils that are sparse in nitrogen. In this case, adding something like manure or blood meal can boost the nitrogen content.

Mulching

Mulching is a preferable method of adding nutrients to azaleas that are growing outside. Mulching helps to lock moisture into the growing medium, preventing too much water from evaporating and drying out the azalea. Any mulch sources should be acidic, such as leaf mould and decomposing pine needles, pine straw, or bark chippings.

Pruning

While azaleas don’t need that much help to grow effectively, it’s often beneficial to prune them. This not only helps the health of the plant but also allows gardeners to sculpt their azalea shrubs into the desired shape. During the flowering season, deadhead any spent flowers. This helps the azalea focus nutrients and energy into younger buds.Azaleas should then be pruned in the late spring or early summer once their final blooms have dropped. Target old or dead branches and any that show signs of disease or damage. Trimming these away helps thin out the plant, improving the air circulation. Never cut azaleas back right to the ground though as this will weaken the shrub too much.

Repotting

Azalea plants that are grown in containers will need to be repotted every year or two. This allows the shrub to keep growing without being restricted by an old pot. This should always be done in the spring before new flowers emerge. When transferring the azalea to its next pot, retain some of the old soil to help the shrub acclimatise. Then add some fresh acidic growing medium and mulch to the new pot. This provides plenty of nutrients to help the azalea keep growing.

Propagation

Azalea shrubs are best propagated through cuttings. For deciduous azaleas, take heel cuttings during the early spring. These need to be semi-ripe cuttings from fairly young shoots. These shoots will need to be grown in greenhouses or cold frames for a couple of years before planting. For evergreen azaleas, take some heel cuttings from mid-summer once flowering has finished. Evergreen azalea cuttings are hardier than deciduous cuttings.

Common diseases and pests

Lacebugs – These sap-sucking pests target azaleas that are grown in brighter sunlight conditions. The main symptoms include mottling on the leaves and brown debris on the underside of the foliage. Clear lace bugs by using organic pesticides. Leafy gall – This pathogen can infiltrate azaleas through the roots or stems. It causes shoots to grow abnormally. While not usually a pressing concern, leafy gall can be a big problem for azaleas. Pull off infected leaves and replace the contaminated soil of the plant. Spider mites – These are another type of sap insect that can affect azaleas. Spider mites typically occur if an azalea is growing in dry conditions. The presence of fine webbing around the leaves is the main symptom. Using insecticidal soap or neem oil is the best way to remove them.

Summary

Azalea shrubs are an impressive but low-maintenance way of bringing a wide array of spring colour to most gardens. Azaleas like shaded areas and moist, acidic soil supplemented with mulch. They don’t require a lot of fertilising or pruning and can be deciduous or evergreen. Azaleas also make excellent candidates as container shrubs for smaller gardens.