The Azaleas

Talking about an Azalea plant means talking about an entire plant genus, among the most widespread and diversified in the world and above all among the most popular as an ornamental plant. Despite all this fame, few know that Azaleas and Rhododendrons belong to the same family; yes, the plant family is that of the Ericaceae and the genus is precisely the Rhododendron. So what we are telling you is that two of the most famous flowers in our homes are… brothers, and almost twins! Some of the subgenera that we can most often meet in our latitudes and in our vessels are: Azaleastrum, Candidastrum, Hymenanthes, Mumeazalea, Pentanthera, Rhododendron, Therorhodion and Tsutsusi. However, in our discussion, we will make use of the term Azalea, both because it is our title and therefore our topic to be developed, and because it is the name with which this species is best known and recognized. Azalea is a plant native to Asia and North America; in particular the countries from which many famous species come are Nepal, Vietnam, China, North Korea and Japan for the Asian continent, Florida in the United States and some regions of Canada. Obviously, given the relevant geographical distances and the very different climates, it will be a question of various species and subgenera with more or less slight particularizations and differences. The name Rhododendron (which we remember is the botanical name of Azalea and groups something like five hundred different species) comes from two Greek words whose meaning is "pink tree"; this probably refers to the typical color of this plant genus, the one with which it occurs most often: pink. In reality, the colors of Azalea vary between white and magenta, passing through pink, fuchsia and red, with some sub-genres that even present double colors. Azalea is basically a shrub plant, therefore of limited size (in adult forms the height varies between 50 and 90 centimeters), which has small and oval-shaped leaves, with a dark green color of the exposed surface and a more pale and tending to darker colors in the lower part of the leaf itself; moreover they have glabrous margins and a very light superficial hair. The flowers are also limited in size, simple but united in small clusters, characterized by a chalice with five sepals and a corolla with five petals; there can also be double forms, in which there are several flowers joined to the same base, which is usually the axillary area of ​​the leaf itself and always at the end of the twigs of the plant. Azalea also has fruits, capsular in shape and brown in color, containing a large number of very small seeds.

Environment and exposure

The great variety of species of Azalea allows this plant to be cultivated and to withstand practically all exposures, from full and direct sun to the shady interior, with the important specification that especially in changes in exposure there is a gradual transition and not a overhang. In general, however, to ensure the survival of one's Azalea with good growth and health, it is necessary to avoid direct exposure to sunlight in the hottest hours of the day, while it is also good to give the plant the late afternoon or early morning sun. . Another tip is to keep the Azalea away from winds of any kind and absolutely protected from frosts (not only in winter but also in spring); therefore in spring and summer it is advisable to keep the plant in a shady and quite humid place, while in winter (i.e. in the most luxuriant flowering period) it is preferable to take it indoors and sheltered, avoiding all sources of heat and direct sunlight. The temperature defined as optimal for the growth of Azalea is in the range between 8 and 16 degrees centigrade.


The preferred soil for azaleas kept in pots is particularly airy and soft, without limestone and slightly acid. The soft and airy consistency can be obtained through the use of peat, moorland, pine needles and with perlite; instead, the slightly acidic pH and above all the absence of limestone are used to avoid the yellowing of flowers and leaves and to preserve a bright appearance of the colors (therefore it is also good to avoid limescale from the irrigation water)

Planting and repotting

The indications for repotting are to carry it out every three years approximately in the period of the end of winter; the plant does not have a very evident and rapid growth, therefore the repotting operation is not so necessary every end of winter but it is good to respect the timing and try to anticipate the first spring heat that must be exploited by the plant already in the new pot to survive and get strong. Planting for Azalea is not only in winter, because as we have already mentioned in "Environment and exposure" this plant does not like direct sunlight practically never during the year, so in summer it is good to protect it from direct light during the most intense hours and in winter the same operation is useful to avoid temperature changes and frosts.


Azalea, as we have seen, is a fairly resistant plant against hot or cold climates, while the watering and irrigation operation must be carried out with great care because this plant desires a substrate that is always kept humid but cannot survive the stagnations of water. For this reason, watering must be frequent but very light, and above all, limescale-free water must be used to prevent the flowers and leaves from turning yellow. In this regard, we can recommend the use of rainwater or distilled water (preferable) for watering, with sporadic sprays on the foliage of the plant with water mixed with thiophanate metyl, a useful component to prevent the limestone possibly present in the water for the irrigation yellow leaves and flowers.


The Azalea plant does not particularly need to be fertilized, but in the spring and summer period (approximately from April to September) it is good practice to administer it every fortnight with liquid fertilizers. Liquid fertilizers with acidic characterization are preferred, ie urea and similar products, precisely because the soil that Azalea loves most is mainly acidic. We also advise you to administer nitrogen-based fertilizers in early spring to help the recovery typical of this period, based on potassium in the height of summer heat and slow (i.e. slow-acting) fertilizers at the end of September. From this point onwards of the year, throughout the winter, there is no need for any addition of fertilizer of any kind.


Although we have previously specified that the azalea has small fruits and contains many seeds, it is not in this way that the propagation of this plant occurs, because the seeds are used only for genetic improvement operations and for other practices related to grafting. The easiest and most effective reproduction of Azalea is by cuttings: in the period of July a series of cuttings (semi-woody shoots of about 10 centimeters) are taken from the plant, these cuttings are put to root in a wooden box (with soil almost exclusively of peat and perlite) and kept at about 20 degrees centigrade with frequent nebulizations for about a month; after this period we will notice a slight rooting, and this is the time to put them in a pot of about 8 cm in diameter with that soft and airy soil whose characteristics we have already explained previously. When we notice the first germination (after about two months) it will be necessary to repot in a double diameter pot (about 15 centimeters) with always soft and well-ventilated soil (brumiere soil, pine needles, peat and perlite).


Azalea is a plant that, given its size, does not need great pruning; only a very light thinning and pruning at the end of spring or early summer (about June) is useful with the elimination of dried flowers. What is important to do, especially if it is a young and growing plant, is to operate training pruning, that is to use those techniques that give a straight shape to the plant also with the help of external supports to the trunk and branches.


The blooms of the Azaleas vary greatly from species to species and from subgenus to subgenus, but the most abundant are found between winter and spring, perhaps due to the particular climatic conditions that in these periods are found in the Asian countries of origin of the plant .

Diseases and parasites

Azalea is affected by fungi only in greenhouses, so it is a rather rare case; in the apartment, on the other hand, it is possible that this plant is attacked by red spider mites or miner larvae (erosion of the leaves), in which cases special products are available for sale widely on the market. If the plant has slightly withered and discolored flowers and leaves then a scarcity of water supply is to be taken into consideration (in these cases we act drastically even by immersing the entire vase in water for a few seconds), while if we notice some brown spots always on flowers and leaves then it means that there is too high a temperature and low humidity around the plant (the solution is to spray as already indicated and ventilate the environment).


Pliny refers to the toxicity of some species which caused intoxication of the Roman army in the East; NASA studies for the ability to absorb formaldehyde and ammonia in the atmosphere; symbol of female "temperance".

Video: Azalea Tour and Care

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