Table of contents:
- Requirements of rhododendrons for growth conditions
- Purchase of rhododendrons and their maintenance before planting
- Seat selection and landing
Video: Choosing A Place And Planting Rhododendrons, Growing Conditions
Read the previous part. ← Types and varieties of rhododendrons
Requirements of rhododendrons for growth conditions
The originality of the requirements of rhododendrons to care for them is caused by the peculiarities of their structure. First of all, these plants have thin superficial roots that do not tolerate increased salt concentration, drying out, and strong waterlogging. They lay the buds of the next year early, in late August - September.
Rhododendrons should not only overwinter, but also preserve large, well-developed flower buds in unfavorable winter conditions (frosts, thaws, wind, sudden temperature changes in early spring), and evergreens also have overwintering leaves. These plants grow slowly, recover very poorly after damage, so it is so important to create suitable growth conditions for them and keep them in unfavorable periods.
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The requirements for rhododendrons are quite specific.
Shine. Usually, light-loving and shade-tolerant and even shade-loving species are distinguished, however, all rhododendrons grow well in diffused lighting, when shaded from the midday sun. Bright sun is harmful mainly in winter and early spring, before the soil thaws. Too much sunlight, combined with frost and the inability to absorb moisture from frozen soil, burns evergreen leaves and well-developed buds. When planting in more illuminated places in the summer, you need to better monitor the soil moisture, and cover the rhododendrons with covers for the winter.
Temperature.We are only considering cold-resistant rhododendrons. But they also have cold resistance and, in general, winter hardiness of different species and varieties differ. The most cold-resistant are: yellow rhododendron, Japanese, varieties of the Lights series, most varieties of Finnish selection. However, despite the fact that some Finnish evergreen rhododendrons are very cold-resistant (they can withstand frosts down to -40 ° C), their burns are possible in winter. In general, deciduous rhododendrons overwinter better than evergreens.
Moisture.Rhododendrons are moisture-loving and do not tolerate drying out of the roots. Their root system is shallow (usually no deeper than 60 centimeters), highly branched, so the plants need systematic watering. Keeping moisture in the soil is also of paramount importance to them. Mulching the soil around rhododendrons is mandatory and more important than for most other plants.
Rhododendrons do not tolerate prolonged stagnation of water, since this disrupts the respiration of the roots. But groundwater rarely harms rhododendrons, because the roots do not go deep into the ground. Rhododendrons, especially evergreens, like high air humidity, so it is useful to spray them with water in hot, dry weather. They feel good on the shore of the reservoir. In general, the damp Petersburg climate is favorable for them.
The soil.Rhododendrons need a fairly light, moisture-absorbing, breathable soil. The main feature is soil acidity. Unlike most ornamental plants, they can only grow on slightly acidic or even acidic soils. Lime is not only unnecessary for rhododendrons, but also harmful.
On calcareous, alkaline soils, and sometimes on neutral soils in rhododendrons (especially evergreens), leaf chlorosis (yellowing) is observed, which greatly inhibits the plants. Acidic soil is necessary for the assimilation of iron and aluminum, but phosphorus in acidic soil is poorly absorbed, and its introduction in large quantities is useless. There are recommendations to introduce phosphorus not in the form of water-soluble superphosphate, but in the form of phosphate rock, which gradually dissolves in an acidic medium.
Potassium is important for rhododendrons, especially in the form of potassium sulfate. Fertilizers containing chlorine are undesirable for them.
Nitrogen is needed in limited quantities in spring at the beginning of the growing season and immediately after flowering during the growth of young shoots. At the end of summer and autumn, additional nitrogen is harmful, as it prolongs the growing season, worsens tissue maturation and can lead to secondary growth of shoots, i.e. to the appearance of young shoots in the fall from new buds already formed by the fall. Such young shoots weaken the plant and freeze in winter. It is better to fertilize rhododendrons with dissolved fertilizers with a reduced concentration, so as not to burn the roots.
Fresh manure and compost cannot be used as organic fertilizers. Well-decomposed humus, leaf soil, pine litter (litter taken from under the pine) are useful. For the successful growth of rhododendrons, the presence of a specific mycorrhiza in the soil is important, which is always present in places where pine trees grow, in a pine litter. Mycorrhiza can be introduced into the soil by taking the soil from under the old rhododendrons. However, there is a risk of infection.
The requirements of almost all considered rhododendrons are close, but they are especially critical for evergreen species and varieties. The most resistant deciduous rhododendrons easily adapt to other conditions: they grow on ordinary garden soil, put up with both bright sunlight and significant shade, and do not require special preparation for winter.
Purchase of rhododendrons and their maintenance before planting
It is better to purchase rhododendrons from reliable companies. Finnish rhododendrons are good. I do not recommend buying Polish or Dutch plants, although good options are possible. Cheaper rhododendrons can be purchased in Russian nurseries that breed the best varieties for our climatic conditions, including Finnish ones.
It is better to purchase rhododendrons in spring, perhaps in early autumn. It is better not to plant the plants purchased in October, but to dig directly in the pot and cover or store in a frost-free room. In the spring, if the soil has already thawed, non-flowering young rhododendrons can be immediately planted in the ground. Planting material from greenhouses, especially those already flowering, it is better not to plant until the end of severe frosts.
After soaking the plant in a pot (or you can first remove it), it is advisable to transplant the rhododendron without destroying the coma into a larger pot, fill the gap between the walls with peat. Soaking can be done not just in water, but in a solution of heteroauxin or special bacterial preparations. In this state, the rhododendron should be kept in a cool room or in the shade outside (in the absence of frost). In a dry environment, it is important to spray rhododendrons, especially evergreens.
Seat selection and landing
Rhododendron Finnish grade "Tigerstedt"
It is very important to choose the right place for planting rhododendrons. This should always be done based on two criteria: aesthetic and plant compliance with its requirements. The use of rhododendrons in garden design will be discussed at the end of the article.
Despite the fact that different types of rhododendrons have different requirements for illumination, for all these plants the best place is in diffused light, in partial shade. Rhododendrons should be shaded from the midday sun, and most importantly in the spring. Therefore, if the shade is formed by deciduous trees, rhododendrons will not be protected in spring, and this must be taken into account when planting.
Do not plant them next to trees and shrubs with a powerful, especially spread root system. Good neighbors for rhododendrons are pines, both varietal and wild. They can not only shade rhododendrons, but give pine litter useful for them. You should not plant rhododendrons in very dry or flooded or windy places.
The timing of planting or transplanting rhododendrons may be different. Large rhododendrons, especially flowering ones, should preferably be replanted in early spring before the soil is completely thawed. In such conditions, it is easier to keep the root ball intact. It is “cut down” from the ground that has not yet thawed.
In this way, I was able to replant old very large specimens without compromising flowering. You can transplant rhododendrons, especially early flowering, and immediately after flowering before the active growth of young shoots. Plants grown in containers can be planted almost all spring and summer until September (not in hot weather).
Rhododendrons have a shallow compact root system, so the pit can be shallow and wider from 50x30 to 70x40 cm. In damp places, it is better to raise the seat and make drainage. The pit is filled with a mixture of garden soil, peat, leafy soil or well-decomposed compost, humus. You can not put manure, a large amount of mineral fertilizers, lime, ash in the pit.
It is good to add coarse sand, especially if the base soil is heavier. An important component is pine litter, pine earth, chopped pine needles or small branches. The soil should be slightly acidic or acidic (this is especially important for evergreen rhododendrons). You can add a tablespoon without a slide of complete mineral fertilizer to the pit. If it is difficult to create the necessary soil on your own, you can use ready-made soil for azaleas, which is available in specialized stores.
Rhododendron seedlings are always sold in containers, and most often they are filled with a light airy peat substrate, therefore, before planting, the root ball must be soaked in water directly in the pot, or after removing it from it.
It is useful to soak the root system in a solution of heteroauxin or special bacterial preparations, for example, Extrasol. The root ball taken out of the pot must be carefully examined, cut out areas of dead, dried or rotten roots, if any. The root ball of rhododendrons is usually dense, entangled in roots, often covered with "felt" over the surface.
If such a plant is planted immediately, it most likely will not take root, the roots will not be able to emerge into the soil of the planting pit. This is the main reason for the death of rhododendron seedlings. It is not necessary to completely destroy the lump before planting, but it is imperative to cut the surface "felt", if there is one, carefully remove it, untangle the surface roots with a sharp stick, so that when planting, the ends of the roots are directed downward and to the sides.
Rhododendrons have a pronounced root neck, which should not be buried. After planting, the seedling should be at the same level as in the pot (if the roots did not stick out in the pot, which sometimes happens). The place of transition of the aboveground part to the underground (neck) is very useful to cover with coarse sand.
This will prevent stagnation of water in this place and prevent the neck from podoprevanie, reduce the likelihood of root rot. Before planting, water should be poured into the hole so that the soil in it settles and its lower part is moistened. After planting, the plant also needs to be watered and after absorbing water, the tree trunk circle should be mulched. Mulching is useful for all plants, but for rhododendrons it is especially important because they have shallow roots and they are very afraid of drying out the soil.
You can mulch with different materials: peat, leaf humus, pine needles, and for decorative purposes - with crushed bark (special colored bark mulch is also sold). Mulching has to be systematically renewed. Rhododendrons, like other plants, are best planted in cool, damp weather, but in any case, it is advisable to shade them after planting by wearing a newspaper cap, a cloth cover or something similar.
Shading can be removed after a week or two, depending on the weather. In the first summer after planting, rhododendrons do not need to be fertilized, but it is important to systematically water, spray, especially in hot, dry weather. Rhododendrons should be watched to determine when they will take root and begin to grow, or to notice signs of trouble.
Read the next part. Rhododendron care in spring, summer and autumn →
Tatyana Popova, gardener
Photo by Vladimir Popov
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