Evergreen shrub native to Asia; dozens of species belong to the rhododendron genus, widespread in most of the northern hemisphere.
The azalea indica has thin stems, densely branched, reddish-brown, woody; the foliage is dark green, slightly rough and leathery, covered with a sparse hair. Overall, the shrub takes on a rounded shape, and in general the varieties grown as indoor plants do not exceed 30-50 cm in height. During the winter months, towards the beginning of spring, it produces small funnel-shaped flowers, which completely cover the plant, gathered in clusters of three-four; the colors are generally in shades of pink and lilac. There are numerous hybrids and cultivars, with variegated and striped flowers. Indoor azaleas are widely marketed; since they lend themselves very well to forced cultivation in nurseries, flowers are available practically all year long.
The plants of azalea indica they are cultivated as houseplants, therefore at a minimum temperature of 10-12 ° C; in fact they would be rustic species, but the forced cultivation in the greenhouse suggests to be very careful when placing these plants outdoors: you can try planting them in the garden in early spring, possibly in a sheltered place. In general, indoor azaleas are grown in a bright place, but where they are not affected by sunlight for excessively long periods of time, especially during the hottest months of the year.
To get a good growth and a luxuriant development of the azalea indica, we recommend to wet the plant by immersing the jar in a bucket full of water for about an hour and then eliminating the excess by letting it drain. In summer, if the plant is left outside it needs scarce and frequent watering, in order to keep the soil fairly humid, but not excessively soaked with water.
Starting from the fall of the flowers until mid-summer, we recommend fertilizing indoor azaleas every two weeks with an ericaceous fertilizer. If the plant has just been repotted, it is not necessary to fertilize because the fresh soil is already quite nutritious.
The multiplication of this genus of plants to get new specimens can be practiced by seed, at the beginning of spring, keeping the seed compote in a sheltered and not too cold place until germination; the seedlings should be repotted in single containers as soon as they put at least a couple of leaves, they will be planted the following spring. You can also take cuttings at the beginning of summer, which must be rooted in a mixture of sand and peat in equal parts.
Azaleas of this kind, in order to grow well, need a fertile and light soil, with good braking characteristics, so that the formation of root rot is avoided. The soil should have an acid component, not a calcareous one because, in the presence of this element, the leaves tend to yellow quickly.
Repotting should be done, in the late winter period, when the plant has occupied all the available space.
Indoor azalea - Azalea indica: Diseases and pests
Azaleas can be affected by some problems, related to environmental factors, or to the intervention of some parasites. In the event of excessive soil moisture, root rot may occur; the plant can be affected by a particular fungal disease, which causes the withering of the leaves. In this case it is important to intervene quickly, eliminating all the diseased parts, then using copper-based products to counteract the possibility that this problem will recur. The red spider mite, then, can lead to having leaves with yellow spots. To eliminate the problem it may be sufficient to make nebulizations of water to increase environmental humidity, a factor not tolerated by these parasites.