Azalea: plants, location & wintering in the garden and in the house

The azalea inspires with its bloom both in the garden and in the apartment. Here you can find out how to plant the azaleas correctly and how to overwinter them.

Because there are not only room but also garden azaleas, location and care must be adapted to the appropriate needs of the species. We show how pot azaleas differ from outdoor azaleas and what to look out for when planting azaleas.

Azalea: flower, origin and properties 

Azaleas are trees and shrubs of the genus rhododendron and come from Asia. In the past, however, they were considered a separate genus azalea. What is special about azaleas is that you can keep them both outdoors and indoors. The respective groups are referred to as garden or outdoor azaleas and as room or potted azaleas according to their attitude. There are deciduous and evergreen representatives of the trees. These all grow bushy and can reach a height of between 40 and 150 cm. The leaves are entire and egg-shaped, shiny or white flocked. The azalea flowers are eye-catching and come in a wide variety of colors. There are also varieties whose funnel-shaped flowers are filled. Others have simple flowers. The flowering time of azaleas depends on whether it is a garden or houseplant. The indoor azaleas bloom earlier, sometimes from September to April. Garden azaleas, on the other hand, start flowering in April and continue to flower until August.

Difference between rhododendron and azalea: Difficult to define whether it is an azalea or a rhododendron. All azaleas are rhododendrons. Under the name Azalea are some Rhododendron-Species summarized: Frost-sensitive, evergreen indoor azaleas and hardy, winter or deciduous azaleas that only thrive well outdoors. Outdoor azaleas either shed their foliage or change their foliage annually in spring. In contrast, rhododendrons are evergreen, they change their foliage constantly throughout the year and not intermittently in spring.

Planting an azalea as a houseplant

If you have decided on an indoor azalea, there are a few points to consider. If you have chosen a suitable location and taken the right care measures, you will be rewarded with lush flowers in the cold season.

Since azaleas originally come from mountain forests, they prefer a cool and humid climate. However, indoor azaleas were bred accordingly and can now also tolerate warmer and drier conditions, which usually prevail in our apartments.

Find a bright location for the azalea that only allows direct sunlight in the morning or evening. Ideally, the temperature should be between 12 and 18 °C. It is best to gradually get the plant used to the climate in the apartment after you have bought it. For this purpose, it is first placed in a cool and partially shaded place. Allow it little by little more light and warmth. At the beginning of the flowering period, the azalea can also be placed in a lighter, slightly sunnier location, which ensures an even bloom. A south-facing window or a window sill above the heating, on the other hand, are not suitable. It is too warm and too dry for the azalea here, and it does not tolerate draughts. The indoor azaleas like to spend the summer in a sheltered, slightly shady place outdoors.

The azalea is somewhat peculiar when it comes to substrate. It needs an acidic soil and is very sensitive to lime. A special bog bed substrate, such as ours, is ideal Plantura organic acidic soil. With a pH value of 4.0 to 6.0, this is in the acidic range and thus meets the requirements of the azalea. Our peat-reduced soil consists of natural raw materials and can be used both in beds and in pots. Fill the planter with a layer of expanded clay or pottery shards beforehand to improve water drainage. The substrate should always be kept moist and never dry out or waterlogged. Preferably use lime-free tap water or rainwater for watering.

Tip: Since azaleas like high humidity despite being cultivated, you should spray the azaleas in the pot regularly with lime-free water, avoiding the blossoms.

Planting an azalea in the garden

Some species thrive best outdoors and can also spend the whole year outdoors due to their frost hardiness.

If you want to plant an azalea in the garden, a bright or partially shaded location without direct sun is ideal for this. The ideal azalea planting time is between September and November or between March and May. Dig a planting hole that is about four times the diameter of the root ball, as azaleas have extremely shallow and wide roots. Fill the approximately 40 cm deep hole with an acidic substrate to provide the azalea bush with optimal conditions. Now everything is soaked with lime-free water so that the peat can soak up the water. Finally, the azalea is placed in this swampy water-substrate mixture. If necessary, fill up with more substrate and model a pouring edge in order to be able to water optimally. The soil should be kept moist throughout the year. If you want to plant several azaleas, the planting distance should be between 30 and 100 cm depending on the species and growth. In addition to regular watering, one should Fertilize azaleasto provide them with nutrients. A special fertilizer for rhododendrons and azaleas, which maintains the acidity of the substrate, is particularly suitable for this - for example ours Plantura organic hydrangea fertilizer.

Overwintering azaleas: Which azaleas are hardy?

Not all azalea species are hardy. The frost hardiness basically depends on whether the species is deciduous or not. Deciduous species are mostly intended for keeping outdoors and at the same time hardy. That means they can just stay outside in the winter. Evergreen azaleas are intended for indoor use and are not frost hardy. They must be overwintered in a cool and light place. Japanese azaleas and diamond azaleas, on the other hand, are outdoor azaleas that largely retain their foliage even in winter. Like the deciduous azaleas, they are frost hardy.

Overwintering azalea indoors

Azalea houseplants need a cool and light location in winter. The temperature can then drop to as little as 8 °C. Sufficient light is important at this time. Before you put the azalea in its winter place, you should remove all dead flowers and fruit buds. In the spring, it is then ideally placed outside so that it can shine again in the next flowering season.

Azalea overwinter outside

The garden azaleas are hardy and can stay outside in winter. To make the cold season a little more pleasant for them, a layer of mulch is an advantage. This can consist of leaves, for example. Mulch protects the soil and thus the roots from frost. A layer of mulch is also useful in summer, as less water evaporates and the growth of weeds is inhibited. If the azalea is outside in the bucket, you can also mulch it here and wrap the pot in a jute sack or something similar.

Propagation of Azaleas

The easiest way to propagate your azalea is by cuttings. To do this, cut off slightly woody shoots that are about 15 to 20 cm long. The best time for propagation is in early summer for indoor azaleas and from July to mid-September for garden azaleas. Use a sharp knife and cut as diagonally as possible to enlarge the cut surface. Water and nutrients are soon absorbed here. The shoots should have leaves but no flower buds. The leaves are cut off except for the upper pair. Since the cuttings do not root as easily, the use of rooting powder is recommended. This stimulates root formation with the help of special plant hormones. Put the cuttings in pure white peat with a pH of 4.0 - 4.5, which you moisten well. Alternatively, a dark container can be filled with water and the cuttings placed there to root. Now put a plastic bag over the pot to increase the humidity. This creates optimal conditions for the young plant. Finally, place the jar in a bright and warm place.

Tip: Azaleas can also be propagated using sinkers. With this method, the daughter plants initially remain on the mother plant and are only separated after root formation.

In addition, propagation of the azalea via seeds is possible if fertilization has taken place. Detach the seeds from the capsules and spread the seeds directly on a suitable, acidic substrate. Since azaleas germinate in the sun, the seeds should not disappear under the substrate. Put the whole thing in a bright place, around 20 to 25 °C. Be sure to keep the humidity high with the help of cling film or a transparent cover. After about two to three weeks, germination should begin.

Are azaleas poisonous?

Azaleas are poisonous, as are most rhododendrons. Plant parts should not be consumed by humans or pets. For safety, gloves are also recommended when gardening.

Common pests and diseases

Among the most common pests of azaleas vine weevil and spider mites; the latter occur mainly in dry room air. Even mildew can often cause an unsightly sight on the pretty ornamental plants. Some cultivars and species of rhododendron, such as Rhododendron bureavii, naturally have a mealy coating on their leaves, which is not powdery mildew. Kick every now and then Rhododendron cicadas and rhododendron lace bugs, leaving bright speckles on the leaves, sucking the sap from them. Through the fungus Phytophthoraa drive death is caused.

Would you like to find out more about the diverse azaleas? We explain how you care for azaleas and what you absolutely have to consider in order for the posture to succeed.