RHODODENDRONS AND AZALEAS belong undoubtedly to the most beautiful flowering shrubs in our parks and gardens. They are members of the Ericaceae (heather) family and form one genus – Rhododendron. They are usually collectively referred to as rhododendrons. This term is commonly used and therefore we are going to use that name in the text below. Over 1,000 species of such plants are known, coming primarily from north-western China, Japan, as well as South America, the Balkans and the Alps. Over the past 150 years, more than 12,000 different varieties of rhododendrons and azaleas have been bred.
You will find in our offer both their large-flower varieties and botanical species, as well as other plants from the Ericaceae family characterized by similar requirements and methods of care, such as heather, magnolia, kalmia, andromeda, pieris or blueberry. In their natural habitats, rhododendrons usually grow on acid and permeable soils, in areas where precipitation is much more abundant than in Poland. Most rhododendrons grow in the forests, forming their undergrowth.
For successful cultivation of these plants, it is necessary to provide them with humus soil of pH 4-5. Acid peat, which can be enriched with spread coniferous tree needles, oak or beech leaves, heather soil, complies best with such requirements. For rhododendrons which do not lose their leaves for winter, semi-shaded LOCATIONS , protected against drying and cold winds, are the best choice. However, if it is possible to provide the shrubs with appropriate soil, which is humid enough, they can also be planted at sunny sites; however, we should remember about adequate protection for winter time, which will be discussed below. Azaleas have no special requirements concerning the location. They do not require shadow because they drop leaves for winter and feel their best in sunlight.
It is recommended to plant a few shrubs in a group. It enhances the decorative effect, additionally providing favorable conditions for the development of the plants. The nursery material offered by us grows in pots and can be planted practically all the year round except for winter.
PLANTING commences with digging a cavity of ca. 60-70 cm diameter and 30-40 cm depth.
In the case of heavy, loamy soils it should be shallower and wider (see the figure). It is filled with substratum prepared earlier and the plant is placed in it as deep as it was in the container. Then, we form a small concavity around the plant and water it until it is completely filled. After some time, we level off the ground leaving a concavity allowing more abundant watering at a later time. If we want to plant a group of shrubs, the soil of the whole location can be exchanged remembering that the shrubs should be planted at least 1 m from one another.
Rhododendrons and azaleas HUSBANDRY PRACTICES involve a few basic procedures.
Because of shallow root system, the soil in the vicinity of the shrubs should not be moved. Weeds are removed manually. It is recommended to mulch the soil with peat, coniferous tree needles, oak or beech leaves, or bark. Twice a year, at the end of April and on the first days of July, the plants are fertilized using commercially available preparations with 30% ammonium sulfate added. Care should be taken to use no fertilizers with the content of calcium. Also slow-release fertilizers with the release time not exceeding 4 months can be used.
It is beneficial for the plant to remove faded inflorescences, which will result in better growth and more abundant budding. Under appropriate care, the shrubs are sufficiently resistant to frost. Young plants, especially those located at sunny sites and exposed to winds, should be covered for winter with shading mesh, matting or other material, allowing to provide adequate access of fresh air.
Covering the plants with double shading mesh will provide better conditions for survival in winter. If we have access to fresh sawdust we can cover even the whole plants with it. This is one of the best methods. To avoid overheating, the covers should be removed early in the spring as soon as the risk of very low temperatures is over.
Yellowing of the leaves and poor growth are frequent problems arising during the cultivation of rhododendrons. Such symptoms are usually due to inappropriate site selection. To save the plant, the location should be changed immediately to a new one with acid substratum. The plants tolerate transplanting well, provided that they are removed from the ground with as large root ball as possible.
There are few diseases and pests that can affect rhododendrons. Practically no special protection is needed in the cultivation process. However, we can occasionally notice chew marks on the leaves of the shrubs, which indicates that larvae of some insects are feeding on them. In such a case, the plants should be sprayed with one of protection agents against chewing pests. Shrubs growing in inappropriate habitats, or after very frosty winters can be infested with various fungal species, which manifests itself by withering or spots on the leaves. The affected leaves should be removed and the plant sprayed at ca. 7-day intervals with the following fungicides: Bravo, Sadoplon, Fongarid. If the infection has extended to the sprout, which is indicated by wilting and withering of the whole leaves, the twig should be cut off below the changes visible on the bark, and the shrub sprayed with the aforementioned preparations.
If we manage to provide the conditions as specified above, and if we do not forget that it is necessary to water the plants at the time of droughts, rhododendrons, azaleas and other Ericaceae will provide a lot of enjoyment allowing to admire their extremely rich blossom, which usually lasts, according to the variety and species, from mid-April to the end of June.