The azalea impresses both as a houseplant and in the garden bed with its attractive flowers. Its beauty probably also stems from the fact that it brings color to the garden or apartment in winter, when the other plants sometimes even shed their leaves. After the flower has withered, however, the plant looks a bit inconspicuous, almost desolate. This phenomenon causes many people to discard the plant early. This is not necessary at all. This guide shows whether the azalea is hardy and how plant lovers overwinter their indoor azaleas and keep them perennial.
Is the azalea hardy?
Both the garden azalea (Rhododendron molle or Rhododendron luteum) and the indoor azalea (Rhododendron simsii or Rhododendron japonicum) are subspecies of rhododendron. However, it would be a mistake to infer the frost hardiness from the origin.
garden azalea
The garden azalea blooms in the warm season from May to June, in rare cases also in July. She comes from Europe and is therefore used to the local temperatures. The azalea is hardy down to -25 °C. Therefore, garden azaleas need no antifreeze. The plant is mostly found as a hedge plant in private gardens. However, the azalea loses its foliage in winter.
The situation is different with garden azaleas, which the gardener cultivates in tubs. Since their roots do not reach groundwater and the frost makes it difficult to absorb moisture, these specimens need winter protection, with the bucket size playing a major role in the method of overwintering:
Overwinter garden azaleas in tubs
Tubs with diameters < 30 cm
- Discontinue fertilizer application from July
- move to a frost-free winter quarters
- do not keep it too warm (3 to 10°C is ideal)
Pots with diameters > 30 cm
- Discontinue fertilizer application from July
- relocate to a wind-protected location (e.g. a house wall)
- Place the bucket on a block of wood or a styrofoam board
- Wrap bucket with fleece or foil
- Apply foliage or bark mulch to the substrate
Ideal location for lush flowering
Whether in the first or second year, the following location requirements must be met for azaleas to have lush flowers:
- cool temperatures (optimal are 8 °C to 16 °C)
- little sunlight
- no draft
If the ornamental shrub is at the mercy of the wind, it draws its sap from the outer branches inwards to protect itself. This greatly reduces flowering. In addition, strong sunlight leads to withering of the flowers and leaves. The pale light of the morning and evening sun is completely sufficient for the plant to carry out photosynthesis.
tip: The optimal location for indoor azaleas is the bedroom. This room is usually darkened and pleasantly cool.
indoor azaleas
Caring for several years: instructions
This azalea, on the other hand, is not hardy. But it captivates with its evergreen foliage and the flowers, which appear in the winter months from September to April. The indoor azalea comes from the tropics and therefore requires the following overwintering (important measures are explained in detail after the instructions):
- discard remaining seeds
- Repot azalea
- place bright and cool until May
- put outside after the ice saints
- bring them into the house before the first night frosts
- place in a cool location
- do not place near the heater
- Regularly pluck wilted flowers during the winter
- Cut back before the end of the growth phase
Remove remaining seeds
The remaining seeds in the substrate, like the indoor azalea itself, feed on nutrients from the soil. They rob the plant of important energy sources for healthy growth and lush flowering. The gardener should therefore remove them completely.
Put the azalea outside
If the gardener puts the azalea in the fresh air, it is best to unpot it and put it in the bed. This should be in a shady, cool place without drafts. The root ball requires constant moisture, but no waterlogging. After the temperatures drop in the first nights of September, if you carefully follow the instructions for overwintering, flowering will also form in the following year.
Remove faded flowers
Like the seeds in the substrate, withered flowers rob the plant of valuable energy. Since residues that have turned brown are not a pretty sight anyway, the gardener should check his plant regularly and pluck off dry leaves and flowers.
Cut back before growth begins
As with many plants, pruning after the winter rest period promotes new growth of the indoor azalea.
Hibernate an azalea?
Overwintering an azalea is therefore possible. However, the term is somewhat misleading, as the shrub is primarily characterized by its ability to flower in winter. The real challenge probably lies in the perennial cultivation of the plant.
Important care information: The indoor azaleas come from the warm tropics and are not adapted to the European seasons. They open their buds in the dry season, which corresponds to the winter here. Therefore, only water the flowering shrub when the substrate is visibly dry. Only use rainwater (also condensation water if you like) or decalcified tap water for watering. Although the flower opens, the plant is dormant in winter. Fertilizer is not necessary at this time.
Hardy varieties
The following varieties of azalea are hardy and are therefore suitable for staying outdoors all year round:
- Gibraltar (Rhododendron luteum): bright orange flowers from May to June, height of growth: 110 to 150 cm
- Snow Gold (Rhododendron luteum): flowers from May to June, grows 110 to 150 cm high and is ideal for the balcony
- Rococo (Rhododendron obtusum): flowering period also from May to June, comes from Japan and has impressively wavy flower edges, with a growth height of 30 to 40 cm it is rather small