Tips for growing rhododedrons
Rhododendron is wonderful beautiful flowering shrub, amazing with abundance and riot of flowering. As a rule, rhododendrons bloom in May, but there are varieties of rhododendrons with earlier flowering, in March, and the rarest varieties can please you in the summer - in June or July.
Probably almost every gardener is faced with the capriciousness of these aristocrats of the garden when growing them. The fact is that without knowing the characteristics of this wonderful culture, it is simply impossible to grow it. Plants will get sick and refuse to grow for some unknown reason...
But before I tell you how to please rhododendrons, let's figure out what they are.
It turns out that rhododendrons have 2 forms: deciduous and evergreen. The first ones are also called azaleas. The agricultural technology of azaleas and rhododendrons differs slightly. Azaleas - sun loving plants, it is better to sit them on sunny place, and rhododendrons love light shading.
The basic principles of growing rhododendrons are:
1. First of all, the PH (acidity) level of the soil. The soil must be acidic between 4.5 and 5.5 pH.
Too much acidic soil Rhododendrons won’t like it either, and they won’t grow at all on a neutral one. If you forget about this whim of the rhododendron, of course, you won’t be able to grow it. And if he likes the soil, the plants will grow by 30 cm per year!
Therefore, when planting rhododendrons, only acidic soil is used. The best (native) soil for rhododendron is rotted pine needles. In their homeland, rhododendrons grow in coniferous forests. You can also mix peat and pine needles in equal proportions. Such soil is the key to success. I must also say that root system Rhododendron is very compact, so it is not necessary to pour a lot of prepared soil into the hole.
When choosing peat for your pet, pay attention to its PH. Stores often sell neutralized peat, and if you don’t pay attention to its pH, the gardener can then be tormented for a very long time by the mystery of why nothing grows for me? This is exactly what happened to me.
Lack of acid in the soil causes growth to stop, and azalea leaves acquire yellow
, because the plant cannot absorb iron, which takes part in the photosynthesis reaction and the formation of chlorophyll. This disease is called chlorosis.
Acidic peat is raised peat, it has a red color, and it is best to take peat from a safe place, for example, directly from a swamp.
Some gardeners have adapted to cope with the whims of rhododendrons even more easily. Peat can be replaced... with sour apples, or, for example, Japanese quince, if you mulch the soil with them. Regular watering of the soil with a weak solution of vinegar, citric acid and even aspirin also helps.
2. When planting rhododendron seedlings on permanent place, do not bury it too deep into the ground. As they say in the literature, they don’t like it. True, when I planted my first seedlings, I did not take this into account, and it seems that it did not particularly affect the health of my plants.
3. Another nuisance - rhododendrons do not like stagnant water. They even love water very much, but they will not tolerate a wet place. Unfortunately, this is so, and I also had to be convinced of this after the death of one of the seedlings, lovingly planted in a damp place... Some kind of average soil was needed - neither damp nor dry.
4. For better flowering You need to remove faded inflorescences. This promotes the formation of buds the next year. And you also need to apply fertilizer 2 times a year, before flowering (in April) and after flowering (in early June). You need to buy special fertilizer - for azaleas or coniferous crops.
5. The soil for rhododendron should be loose and breathable. Dense sandy soil is undesirable.
6. Evergreen rhododendrons like to be watered deeply before wintering.
In general, compliance with these principles is enough to grow the most beautiful rhododendrons on your site. And I am sure that in the spring your site will turn into a real paradise, and the neighbors will not be able to take their eyes off such beauty.
The variety of colors of rhododendrons is amazing. They are usually colored in white-violet and raspberry-red tones, and azaleas are also orange-yellow.
The azalea's life cycle is strongly tied to the seasons. Early varieties bloom from December to April, mid-late - from January to March, late - from February to April. You can find out more about how many times a year and when azalea blooms. And after flowering ends, the question arises: what to do next at home? First you need to decide what can be considered the end of flowering? A sign of the end of flowering is the drying and dropping of flowers. Some varieties also shed leaves.
Important! If the variety does not allow for leaf shedding, but this still happens, this is a cause for concern. Perhaps your pet is sick.
Step-by-step instructions: what to do next when the rhododendron fades?
At the end of flowering, the azalea must be pruned. This is necessary in order to ensure its subsequent flowering. When pruning, young shoots should be removed, overgrown branches should be trimmed so that three or four leaves remain on it. If the azalea has grown and can be thinned out. If desired, you can form a crown of any shape.
What to do with faded flowers? If there are dried flowers left on the plant, they should also be cut off along with the flower stalks. And trim the extended branches. Pruning is done carefully so as not to injure the plant. This procedure is carried out using a sterile pruning shears around March or April, after flowering has ended.
Pruning is needed for:
- Bush formation.
- Future flowering.
- Beautiful appearance.
- Formation of a lush crown in the future.
After pruning, the azalea should be placed in a dark and cool place for about 2 months. This way you will provide her with a period of rest. During this time the plant will be able to rest and regain strength.
Also, after flowering, pinching is very important, that is, removing the growth point of a young shoot. It is better to pinch 3 times a year. Thanks to it, the crown of the plant will look beautiful and lush, and it will also promote budding. Pruning and pinching are very important for future flowering, its intensity depends on this.
Attention! Before pruning, the pruning shears must be disinfected to avoid infection of the plant. The cut areas should be disinfected with a special paste.
Watch the video on the topic “Should I prune an azalea after flowering?”:
Temperature, humidity, lighting
Azalea is very capricious regarding air temperature. After flowering, which is usually spring period, it needs to be kept at a cool temperature. Optimal temperature 12 – 16 degrees. At the same time, it is imperative to support high humidity air. IN ideal humidity should reach 70%. To do this, you can use a humidifier and also regularly spray the plant. After flowering, it is better to place the azalea dark place. A shaded room or other place with minimal lighting is quite suitable for her.
The water should be cool, but not icy. The optimal temperature is 16-17 degrees. Azaleas should be fertilized after flowering (in spring) at least once a week. For this purpose, fertilizers designed specifically for azaleas are used:
- Ammonium sulfate.
- Superphosphate.
- Potassium sulfide.
After flowering, you need to use fertilizer containing nitrogen., for example, “Uniflor - micro”. This fertilizer helps:
- Vegetation.
- Active growth.
- Recovery.
Important! It is highly undesirable to use fertilizers containing chlorine!
Watch the video on the topic " Proper watering azaleas so they don’t lose their leaves”:
The period after flowering is most favorable for transplantation. Since in this case the load on the plant will be minimal. He will have time and opportunity to recuperate. First you need to select the soil. You can prepare it yourself, but it is best to buy it at the store.
If you decide to prepare the soil yourself, for this you need:
- One piece of leafy soil.
- Two parts of coniferous land.
- One part of heather land.
- One part of peat soil.
All this should be mixed in a container, then add river sand as a leavening agent. You need to put drainage in the pot. After the soil and pot are prepared, the plant should be removed from the old pot and placed in a container of water for about 30 minutes.
About 1/3 of the soil should be washed away from the roots. Then you need to inspect the roots. If you find rotten, diseased, dark roots, they should be removed with a sterile instrument. Then the plant is lowered into the prepared pot and covered with fresh soil. Under no circumstances should the root collar be covered.
After transplanting, the flower should be watered with a solution for root growth. After transplantation, the azalea is not fed for two months in order not to burn the roots and not increase the load on the root system.
Watch the video on the topic “How to properly transplant an azalea”:
Possible errors and their consequences
When caring for azaleas, mistakes cannot be avoided.
It could be:
- Unsuitable soil. The plant will not receive the necessary substances.
- Not a sterile instrument. Can lead to infection of azaleas with pathogenic flora.
- Root damage. Deadly and should be avoided as much as possible.
- No trimming or pinching. Affects appearance azaleas, but is not dangerous.
- Insufficient air humidity. May cause drying and cause some diseases.
- Feeding and stimulation immediately after flowering. May cause root damage and death.
- Watering with inappropriate water. This is fraught with infections.
- Overfeeding or complete lack of feeding. Both can destroy the azalea.
Each of these mistakes can lead to serious plant disease or even death.
Also, improper care, pests and other reasons can cause the plant not to bloom. You can find out more about why azalea does not bloom 
When caring for azaleas, the main thing is not to overdo it. It should be remembered that this is a load. This means you need to provide the plant with maximum peace and the opportunity to recover. Under no circumstances should you feed or stimulate growth immediately after flowering! Darkness, coolness, moisture - these are the main friends of azaleas after flowering.
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Bad landing
Too light, dull, small leaves; depressed look. This indicates a lack of oxygen to the roots (wet dense soil, stagnant water) or a lack of nutrition or water.
How to save it. Right . Plant rhododendron in and make sure that there is no competition with the surface root system. Even too active perennials such as tenacious ones, completely covering trunk circle rhododendron, can deprive it of nutrition and moisture.
Often the outer part of the root ball is also a container formed by dead roots. Their dense felt prevents living roots from penetrating into the soil - as a result, the plant starves. You need to remove this inner container when planting, or at least cut it in several places. It’s a good idea to check if there are any mole or mouse holes in the root area.
How can I help you. , if necessary, water and mulch the plantings, spray the crown. If the plant is planted well, but still lags behind in growth, they can help foliar feeding complete solution mineral fertilizer with microelements. Feeding is required 3-4 times in June-July at half the dosage recommended in the instructions.
Before planting, such a root ball should be freed from the layer of dead roots.
Unsuccessful wintering
Death of leaf tissue or buds on parts of the rhododendron that are above the snow. The problem arises from the alternation of daytime sun and nighttime frost in February and March. If cold weather is accompanied by wind, the leaves of the plant actively evaporate water. The water supply is not replenished because the roots in the frozen ground do not work, and the leaves simply dry out. In deciduous species of rhododendron, flower buds or upper parts of shoots may dry out.
How to save it. When choosing a landing site. In dry autumn, plants are watered abundantly. They install a winter shade - mesh or gauze, sparse burlap on the frame, a protective screen, and the like. In the fall, mulch the bushes with a layer of 7-10 cm so that the soil does not freeze deeply.
How can I help you. In spring, severely damaged leaves are trimmed. The shoots are pruned in June, when it becomes clear where the buds are waking up. Do not rush to cut out the branches of small-leaved evergreen rhododendrons - they very often grow anew along the entire length of the shoot. If the leaves remain in the winter state for too long - drooping and rolled into a tube - spray the crown with water more often. They rake so that the ground thaws quickly and the roots begin to work.
Breaking of bushes by settling crust or wet snow
How to save it. In the fall, structures are installed above the bush that will take on part of the snow load: arches fixed crosswise, a wigwam made of stakes, etc. If the shape and size of evergreen rhododendrons allow, you can tie the bushes with an elastic band.
How can I help you. Broken branches are cut out in the spring. Do not rush and cut off slightly broken shoots: you can try to save them. To do this, you need to connect the edges of the break, tie up the shoot and secure its position with a support. The harness and support are left in place for at least a year.
Damage to leaves by ice crust
Evergreens are most often affected. If the crust does not melt for too long, the lower branches, which are in ice captivity, may completely lose their leaves.
How to save it. Spruce branches or brushwood are placed under the lower branches of the bushes.
How can I help you. In spring, severely damaged leaves and shoots are trimmed.
Frostbite of shoots
Leaves, bark and cambium tissues die, the shoot on the cut is dead - brown. Varieties that are not suitable for a given climate zone suffer. U winter-hardy varieties unripe shoots die. It occurs as a “growing disease” in young plants obtained by the meristem method - tissue culture, as well as in the case of late fertilizing.
How to save it. Selected for planting. Fertilizing is carried out in doses and only at the beginning of summer. In deciduous species, actively growing blind shoots are pinched at the end of July.
How can I help you. In spring, frostbitten shoots are cut back to healthy wood.
Weak flowering
Varieties Caucasian and dense rhododendron Sometimes some of the buds open in the fall. In spring, they bloom weaker. Rhododendron Ledeboura and varieties with its participation try to bloom during winter thaws. IN in this case nothing can be done to help.
Weak flowering of the bush due to lack of light, nutrition or moisture
How can I help you. Improve living conditions. Remove faded inflorescences, preventing seeds from setting.
PROTECTING RHODODENDRONS FROM DISEASES AND PESTSRhododendrons, like any other plants, are affected by diseases and pests. It should be noted that susceptibility to various diseases and pests largely depends on the type and variety of rhododendrons. Long-term practice shows that evergreen rhododendrons growing in open sunny areas, are more susceptible to diseases and pest attacks than those that grow in light partial shade. Weakly growing, depleted specimens are usually more susceptible to diseases and pests than vigorously growing ones. Consequently, the main thing in protecting rhododendrons from pests and diseases is to create optimal conditions for their growth and development. Compliance with the rules of agricultural technology and an informed choice of planting site are essential.
DISEASES OF RHODODENDRON
For the Latvian SSR, rhododendrons are a relatively young crop, so the diseases that we observed are not specific to this particular plant genus. The causative agents of rhododendron diseases can be various microorganisms. In addition, the disease may be a consequence of unsuitable environmental conditions. An active fight against the disease should begin as soon as its first signs are noticed, otherwise one cannot fully count on success in the fight against the disease.
Let us dwell on some diseases of rhododendrons, which, due to the expansion of cultivation of this crop, are becoming more common.
Mosaic of leaves. The causative agent of this disease is a virus that mainly affects the leaves, which become rough, calloused and ugly. The calluses are usually a normal green color and the rest of the leaf turns greenish-yellow. The light part of the leaf blade is much thinner than in places where there are calluses. Venation on calluses is less noticeable. Leaf mosaic virus is carried by aphids, bedbugs and other insects. This disease of rhododendrons has not yet been discovered in our republic, however, by expanding the culture of rhododendrons, we must be ready to fight it.
Leaf spot- the most widespread disease of rhododendrons in open and closed ground. The disease affects both young seedlings and adult plants. Its causative agents are various fungi, the type of which can be accurately determined by the shape of the spots.
Cercospora rhododendri Mar. et Verpl. - spots are irregular, angular, dark brown with reddish edges, especially noticeable on the underside of the leaf. In conditions of high humidity, the upper side of the leaf blade becomes covered with a gray coating. The leaves of the lower tiers are more affected. The leaf spot pathogen is widespread in the United States, especially on Rhododendron pontica and cultivars based on this species. Another mushroom of the same genus, Cercospora handelii Bubak, is also dangerous.
Gloeosporium rhododendri Br. et Cov. - spots are irregular, dry, dark brown or black. This type of disease is widespread in Holland and England on young seedlings of rhododendron ponticus.
Pestallozzia rhododendri Gube, P. guepini Desm., P. macrotricha Kleb. - the spots are large, dry, light brown or gray. Very often the spots are concentric, limited by dark, later black sporangia. These fungi not only cause spotting, but also attack young shoots, leading to their death. In our republic, pathogens of the disease were also found on the root collar.
Phyllosticta maxima Ell. et Ev. - spots are vague, irregular, dark brown or ash-gray, with dark edges. Localized along the edges or ends of leaves. Black balls - sporangia - fall out of the spots. The vast majority of affected leaves die, and the process begins at the tips of the leaves. Similar spots are formed by the fungus Phyllosticta saccordoi Thum.
Septoria azaleae Vogl. causes one of the most dangerous diseases of rhododendrons in closed ground (greenhouse azaleas) - leaf spot. In countries where rhododendrons are cultivated very widely, this fungus is also found on deciduous rhododendrons in open ground. Yellowish, red-yellowish, and later yellowish-gray spots of irregular shape appear on the leaves of plants. By autumn they become dark brown in the middle, and sometimes even brownish-black. At first, the spots appear in the middle of the leaf blade, gradually increase in size and, reaching large veins, stop. The fungus grows into all leaf tissues, the leaves die and fall off prematurely, so that the plant becomes completely bare. As a result of the falling leaves in plants, all physiological processes are disrupted, and flower buds do not form normally. If greenhouse azaleas suffer from this disease for several years in a row, then the branches become thin and long, the number of flower buds sharply decreases every year, and the plants lose their decorative appearance; If the infection is severe, the plant dies. On the spots you can see small, black, dot-shaped containers of spores - pycnidia, immersed in the leaf tissue. A mass of spores emerges from the pycnidia in the form of thin pale threads. Insufficient lighting in the environment contributes to the occurrence of this disease. winter period, high humidity air, excessive watering, excessive and one-sided or late fertilizing with nitrogen, late transfer of plants to the greenhouse in the fall, late removal from the greenhouse in the spring, late pruning of plants, i.e. the main cause of small spot disease in rhododendrons in closed ground is non-compliance with agricultural practices.
Control measures. In winter, plants should receive sufficient lighting and moderate watering. To eliminate excess air humidity in warm days Greenhouses should be well ventilated and dense plantings should be avoided. Diseased and fallen leaves are collected and burned. During the growing season, plants are regularly (every 2-3 weeks) sprayed with a 0.4% suspension of 80% zineb or a 0.5% suspension of captan. If the air is excessively humid, you should not spray plants with preparations containing copper, as this leads to burns of leaves and young shoots. Preparations containing copper are used only at normal air humidity and at a sufficiently high temperature. You can spray only those plants whose leaves have fully grown and developed.
Bud rot was first discovered on rhododendrons in the United States. The disease is typical for the largest rhododendron (Rh. maximum L.) and Katevbinsky (Rh. catawbiense Michx.). The causative agent of the disease is the fungus Sporocybe (Pycnosteanus) azaleae (P.K..), which is spread by the cicada Gnaphocephala coccinea Forst. Buds affected by this disease turn brown and die. Mycelium from buds can grow into branches and cause them to die.
Control measures. During the growing season, plants should be sprayed regularly (every 2-3 weeks) with preparations containing copper.
Leaf swelling(thickness) of rhododendrons is caused various types Exobasidium mushroom. On leaves and shoots affected by this disease, fleshy, pale, waxy, gall-like formations appear, spherical in shape from the size of a pea to a walnut.
The most common causative agent of this disease is Exobasidium rhododendri Cram. This disease usually affects alpine rhododendron species - Rh. ferrugineum L., Rh. hirsutum L. and others.
Exobasidium vaccinii Woronin, the causative agent of lingonberry leaf disease, causes the formation of white cushion-shaped growths on young leaves of evergreen rhododendrons (Rh. maximum L., Rh. catawbiense Michx.) and deciduous rhododendrons in their natural habitats. In the Latvian SSR, this disease is found everywhere on lingonberry leaves, but has not yet been observed on rhododendrons.
Exobasidium burtii forms characteristic spots on the leaves, which are initially small, round, and later, increasing in size, acquire indefinite form. White spores are visible on the underside of the leaf. This disease usually affects Rh. ponticum L. and Rh. luteum Sweet.
Exobasidium vaccinii-uliginosi Bond., the causative agent of blueberry leaf blistering, causes the formation of the so-called “witch’s broom” in the Carolina rhododendron. The leaves become yellow-brown, their undersides become covered with a powdery coating. After a year, these leaves die off.
Exobasidium japonicum Shir, affects leaves and shoot tips. Diseased plants develop abnormally thick, large, pale green leaves covered in a chalky white coating. These leaves quickly wrinkle, become moldy and dry out. On annual plants the fungus is less common than on older ones. Susceptibility to this disease largely depends on the species and variety of rhododendrons.
Bloating of rhododendron leaves has not yet been observed in our republic.
Control measures. The affected shoots are cut out and burned along with the leaves. For prevention, plants are sprayed with preparations containing copper.
Rust of rhododendrons. The causative agent is the fungus Chrysomyxa rhododendri D. C. The disease most often affects small-leaved species - Rh. dauricum L., Rh. ferrugineum L., Rh. kotschyi Simonk, etc. In autumn, yellow, red or brown dusty pimples - sporangia - appear on the underside of the leaves of affected rhododendrons. If plants are heavily infected, they will drop their leaves prematurely. In spring, dark red pads are visible on the leaves - winter spores. Spores of this fungus carried by the wind onto spruce trees cause great harm to the trees.
Control measures. Affected leaves are collected and burned. Sick plants are sprayed with preparations containing copper.
Dry white rot of the root collar of rhododendrons. The causative agent is the fungus Armillaria mellea (Vahl) Quel. (real honey fungus). The disease mainly affects the root collar, as a result of which the plant dies. In diseased plants, the root collar is entwined with a grayish-white ring - mycelium. Strongly growing rhododendrons do not suffer from dry rot of the root collar. This disease usually affects those plants whose root collar is broken or otherwise damaged, therefore, when moving plants with a large root ball, you cannot hold them only by the aerial part; you must also support the root ball.
Control measures. Affected plants are dug up and burned. Plants near which the disease is detected should be replanted so that the root collar is not covered with mulch (it must be dry).
Root rot. The causative agent of the disease is the fungus Phytophtora cinnamoni Rands. The roots and base of the stem most often suffer from this disease. Externally, the disease manifests itself as follows: individual shoots or the entire plant wither, and then all the leaves dry out without externally noticeable reasons. The apical buds turn brown and die. Transverse sections of shoots show that the cambium layer is brown. The roots turn brown and rot, as a result of which the entire plant dies. This disease mainly affects rhododendrons growing in insufficiently acidic, highly moist soils. It is inherent in weakly growing rhododendrons. Young plants are most often affected. Plants become infected through the root system or through wounds.
Control measures. Affected shoots are cut out and burned. If the damage is severe, then the entire plant is burned. To prevent the disease, you should maintain normal soil acidity (pH 4-5) and maintain the correct water regime (you cannot water the plants too much).
Rot of seedlings and young seedlings. Very often, when propagating by seeds and cuttings, one has to observe sudden massive wilting of rhododendrons, rotting and death. The causative agents of this disease are the fungi Rhyzoctonia sp., Pythium sp. and Botrytis sp. The most dangerous representative of this group of fungi is Rhyzoctonia Solani Kuhn. The disease most often affects young seedlings. Seedlings affected by this fungus become brown or black at the root collar, soft, fall to one side and die; white fungal hyphae or brownish mold are visible on the leaves. Pale, cobweb-like threads appear on the surface of the substrate. Typically, the fungus develops if the substrate is fresh, not yet decomposed, or if the crops were watered with water infected with the fungus. The causes of the spread of the disease may be too high a density of crops, excessive humidity in greenhouses and insufficient air exchange. Dense rhododendron crops should not be sprayed with water too often (daily), because excess humidity contributes to the occurrence of the disease. It is better to water them rarely, but abundantly. Our experience shows that it is quite enough to thoroughly wet pots with young shoots once a week.
Control measures. Greenhouses containing crops and cuttings of rhododendrons should be well ventilated and have sufficient lighting. Young shoots and seedlings should be watered in the morning, with the expectation that they will dry out by evening. Overly dense plantings should be avoided. It is also not recommended to plant cuttings and young seedlings too densely. Seedlings that begin to die should be sprinkled with finely ground charcoal to stop the spread of the disease. In addition, the disease can be instantly eliminated by sprinkling the affected areas with foundationol powder. For preventive purposes, it is advisable to spray young shoots and seedlings with a 0.2% suspension of foundationazole. Captan and TMTD can be used to combat this disease. Cuttings of greenhouse azaleas are disinfected by keeping them in a 0.15-0.2% TMTD suspension for 10-15 minutes.
Dying of shoots. The causative agent is the fungus Phytophtora cacto-rum Leb. The apical buds of the affected plants do not bloom, they turn brown and then die completely. The shoots also dry out first and then die. Adult leaves curl, turn brown and dry out. Severely affected plants die. The death of shoots can also be caused by the fungus Physalospora rhododendri. In diseased plants, on some shoots the leaves turn brown, dry out, and then the entire shoot dies (Fig. 26). IN last years this disease was also discovered in the Latvian SSR. This disease also affects lilacs.
Control measures. The affected leaves are collected, the shoots are cut out, and the whole thing is burned. After flowering, rhododendrons are regularly sprayed with preparations containing copper. Spray every 10-14 days. Rhododendrons should not be planted in full shade.
Let's give a few examples. If the substrate is incorrectly selected (alkaline environment), rhododendron leaves become pale, i.e., typical chlorosis appears. In alkaline and even neutral substrates, iron, which plays a large role in the formation of chlorophyll, is in a form that is not absorbed by plants. In this case, plants grow weakly, succumb to diseases more easily and ultimately die. If the planting site is chosen incorrectly, rhododendrons suffer from a lack or excess of light, from exposure to cold, dry winds, etc. The leaves of such rhododendrons are disheveled, the plants have a stunted appearance, although they are still alive and growing.
Excess moisture is not typical for sandy soils, but with artificial watering, mineral elements are often washed out, and the plants show signs of starvation.
Damage from frost and sun, sometimes called "sunburn". This disease is usually observed in the spring after severe frosts or at the end of winter when sharp fluctuations temperatures day and night. Brown, dry, irregular spots appear on the leaves of rhododendrons, as a result of which the plants lose their decorative properties. In the climatic conditions of the Latvian SSR, brown spots on the leaves of evergreen rhododendrons appear in late February - early March, when at night the temperature drops to -15 ° C, and during the day in the bright sun the surface of the leaves heats up quite significantly, because the temperature rises above zero.
To avoid sunburn, rhododendrons should be planted in semi-shaded areas. However, if you have to plant rhododendrons in an open place , then it is necessary to create light partial shade for them. The most the best material A spruce paw is used for this purpose. Rhododendrons are very tenacious and, if the rules of agricultural technology are observed, they form strong shoots with beautiful foliage, which already in the middle of this summer partially covers the damaged leaves.
Sometimes " sunburn"appear not in the form of spots, but in the form of a brown stripe running along the main vein of the leaf. As is known, the leaves of evergreen rhododendrons, even at a temperature of -3°C and below, are rolled into a tube in order to reduce the leaf surface, “hide” the stomata and reduce transpiration to a minimum. The side of the rolled leaf that faces the sun gets very hot during the day and freezes at night. In spring, on the surface of untwisted leaves, a reddish-brown or brown belt is noticeable, stretching along the entire leaf. If the damage is not severe, then with the beginning of the growing season the signs of freezing disappear and the color of the leaves becomes normal. During severe frosts, flower buds of rhododendrons may also be damaged. If flower buds do not bloom in the spring, but turn brown and dry out, it means they froze during the winter frosts. In the climatic conditions of the Latvian SSR, flower buds usually freeze out at less winter-hardy species rhododendrons.
Of the rhododendrons in the natural flora of the USSR, the most sensitive to low temperatures is the Daurian rhododendron. Usually in the mild climate of our republic it grows and develops very well, annually in the second half of summer it forms a large number of flower buds, however, if the winter is replete with thaws, the buds begin to bloom, and then even with a slight sub-zero temperature freeze out. So, in 1976, when December was very warm, Daurian rhododendron began to bloom in the open ground on December 26, and when by New Year the temperature dropped to -10 ° C, all the buds that began to bloom froze. In the summer of 1977, the rhododendron did not bloom. In 1977, the second half of November and the beginning of December were unusually warm, and on December 4, some Daurian rhododendron bushes were covered with flowers; On December 6, the temperature dropped to -2° C, and the buds froze. The story of the previous year repeated itself. We observed a similar picture with Sikhotinsky and acuminate rhododendrons. These observations indicate that rhododendrons originating from areas with a continental climate have high frost resistance, but their winter hardiness is low, and they are of little use for cultivation in the climatic conditions of the Latvian SSR.
Water deficit in summer and winter drying out of rhododendrons were the main reasons for the death of most of the rhododendrons planted in 1958 in Riga parks. It should be noted that water deficiency in rhododendrons planted in Riga parks was felt not only in winter, but also in summer and autumn. It was due to the fact that groups of evergreen rhododendrons were placed under large old linden trees with a powerful superficial root system. The rhododendron planting sites were not isolated from the root system of the linden trees by roofing felt, slate, or tin. From the point of view of light, the choice of place for rhododendrons was not bad, but within a year the root system of the linden trees intertwined the entire top layer of soil, resulting in a large deficit of water and nutrients necessary for the development of rhododendrons. Since the roots of rhododendrons are collected in a dense ball, they could not withstand strong competition from the surface root system of linden trees and were unable to provide the above-ground part of the plants with water and nutrients. Being under the powerful roots of linden trees, rhododendrons did not receive moisture from atmospheric precipitation. In addition, these rhododendron plantings were not provided with regular watering. As a result, out of several thousand plants planted about twenty years ago, only a few dozen specimens have survived to this day.
To protect evergreen rhododendrons from drying out in winter, it is recommended to water them abundantly before the onset of frost, saturating all plant cells with water as much as possible.
Chlorosis is caused by an acute deficiency of iron and magnesium, which is observed in cases where the pH of the substrate is above 7. In plants affected by chlorosis, the leaf blade between the conducting bundles (veins) becomes light green or even yellowish-green. IN initial stage affected by chlorosis, the veins still retain a dark green color, and then also turn yellow. With severe chlorosis, all young shoots become yellow or pale yellow and are easily burned in the sun. The occurrence of chlorosis is caused by a high calcium content in the soil and in irrigation water. Iron and magnesium are necessary for normal chlorophyll synthesis, but in an alkaline environment they are in an indigestible form, although they are contained in sufficient quantities. In addition, if the environment reacts incorrectly, the mineral nutrition of plants in general is disrupted. To eliminate chlorosis, the pH of the medium should be brought to 4.0-5.0, which will help to establish mineral nutrition for plants, which will acquire a normal appearance.
Nitrogen starvation. With a lack of nitrogen, the entire leaf blade of rhododendrons becomes light. New shoots grow weakly, small leaves develop on them, and flower buds do not form. In mid-summer, around August, the leaves of previous years begin to turn very yellow, then become reddish-brown and most of them fall off. By the end of summer, only leaves of the current year remain on the plants, although when normal conditions growth and nutrition on an evergreen plant, the leaves remain for four years. These signs indicate that the plants are starving, and, in particular, experience an acute lack of nitrogen. If rhododendrons are regularly fed annually, they will not experience nitrogen starvation.
Our observations show that nitrogen starvation in rhododendrons occurs when they are grown on light sandy soils that require regular watering throughout the summer. With abundant watering using sprinklers, mineral salts, especially nitrogen compounds, are washed out and a deficiency of mineral elements is created.
When the first signs of nitrogen starvation appear, you should immediately add nitrogen fertilizing(ammonium sulfate or potassium nitrate).
Soaking rhododendrons. In practice, we encounter not only drying out of rhododendrons due to water deficiency, but also wetting of rhododendrons as a result of excess soil moisture. In these cases, the leaf blade of rhododendrons becomes grayish-green and dull. Leaves fall for no apparent external reason. New shoots become soft, leaves wither, and the root ball is destroyed, although the roots at the root collar are not damaged. These signs indicate that there is excess moisture in the place where the rhododendrons are planted, which is due to poor drainage in top layer Excess water accumulates in the soil, which means that the aeration of the root system is clearly insufficient. Wetting of rhododendrons is usually observed if they are grown on heavy, clay soils with poor drainage, and also if after transplanting they are watered abundantly and often.
To create normal water and air exchange for the root system, it is necessary to ensure good drainage, soaked plants should be transplanted into a loose water- and air-permeable substrate, and stop watering for a while. On hot, sunny days, watering should be replaced by spraying the aboveground part with water. Plants that get wet restore their normal appearance relatively slowly.
In order to avoid rhododendrons getting wet, they should be planted in a specially prepared water- and breathable substrate in a well-drained place. Watering throughout the growing season should not be excessive.
KONDRATOVICH "RHODODENDRONS", Riga, 1981 (experience of the introduction of rhododendrons in Latvia)
The question “How to revive an azalea?” most often occur in people who are unprepared for the appearance of this flower in the house - it is usually given as a gift, trying to please the hostess. At first everyone admires flowering plant, and later disturbances begin due to yellowing, blackening or drying of leaves, as well as falling flowers. In such cases, you need to urgently decide how to save the dying azalea.
It is advisable to know at least something about rhododendrons before adding them to your home. Because of the difficulty of care, azalea is called a capricious beauty. But if she settles in comfortable conditions, she will delight her owners with a healthy appearance and lush flowering. You just need to line it up so that there is balance in everything.
Azalea feels great at air temperatures no higher than +22 °C in summer and +15 °C in winter. In this case, there should be enough light, but without direct sun rays. The pot and air should be humid (80%), but it should not be sprayed during flowering. The soil needs to be acidic. Trouble begins when these conditions are violated.
If the leaves begin to dry out, change color, or become stained, you need to find out why this is happening and eliminate the cause. Leaves can fall very quickly. They turn yellow as a result of pest attack - then you need to take prompt action. And if a lot of calcium has accumulated in the soil, adding a little citric acid to the water will help.
The main cause of leaf falling is excessive dryness and heat air. As soon as the greenery begins to dry out, you need to lower the air temperature (this will make it easier for the plant to recover), water it with settled, acidified water, and spray the flower.
If your azalea is drying out, give it a cool shower. Most likely, tap water contains a lot of salts and unnecessary impurities (which is why it is settled), so you will have to use a watering can with a fine sieve to bathe it with clean, settled water with the addition of citric acid. You can immerse the pot in a basin so that the water is 2 cm above the rim, leave it for 20–30 minutes, then let the excess water drain. Just fill the flower with acidified water!
If the azalea has dried out
What to do when the azalea has dried out and completely lost its leaves? Don’t rush to throw it away, even if it’s dried out. If the roots are still alive, that is, have not dried out, then you can revive the plant with water, cooling and boric acid. You just need to be patient.
First you need to get rid of the old soil. To do this, remove the plant from the pot, pour in the roots and a lump of earth. clean water. As the soil becomes wet, slowly and carefully remove (wash) it with your hands; you can place the soaked roots under running water and rinse. Then the plant can be planted in new soil, purchased specifically for azaleas and laid on a high-quality drainage layer in a new pot. It is advisable to add to the soil wood ash or Activated carbon, put a layer of pine needles on top. The transplanted flower should be placed in a softly lit place with an air temperature no higher than +20 °C and left until the morning.
The next day, the plant must be watered with water that has stood for at least two days, adding a few drops of boric acid and Zircon to it. When all the soil flows well with water, the excess should be poured out of the pan.
The roots will better absorb nutrients at lower temperatures, so the pot can be lined with ice. Some gardeners say that in the summer, a pot of azaleas should be put in the refrigerator for a day. Such procedures - watering with boric acid and Zircon, cooling - must be repeated daily until new leaves begin to grow. Then you can water every other day, sometimes replacing boric acid lemon, and replace the refrigerator with sprays.
How to reanimate after pests
Having gotten rid of the reason why the azalea, damaged by pests, dried up, you can begin to restore the plant.
Affected leaves need to be removed (if they have not fallen off on their own); bare branches should not be trimmed. In order for the azalea to revive its branches, it must be in comfortable conditions, but it is advisable to further increase the air humidity by covering the plant with a transparent lid (bag, jar). To strengthen the immune system, it is sprayed with a solution prepared from the drug “Elina”. Water frequently (daily or every other day) with acidified, settled water.
How to reanimate after illness
Azalea diseases are the result of bugs. These can be caused by changes in air temperature and humidity levels. If the leaves of an azalea turn black, the cause may be the Black Triassic or infection with fungal diseases. Septoria (red-yellow spots with black dots), cercospora ( brown spots with red edges on the underside of the leaf), phyllostictosis (brown or gray spots) are characterized by the presence of spots that appear and grow on the leaves and stems of the plant. Late blight affects the roots, and is indicated by curling and drying of the leaves, which first darken, starting from the very tips, change color, and then curl and.
These diseases will be prevented from progressing by special drugs that need to be started as early as possible: Bordeaux mixture, Fundazol, Ditan, Topsin-M or other fungicides. With verticillium, the base of the stem darkens, not the leaf; this can more likely lead to death. Timely processing will save copper sulfate or fungicides. The sooner the disease is identified, the sooner treatment will begin, which means there will be more hope for the complete recovery of the plant.
After use special drugs it is necessary to destroy all affected parts of the plant to prevent the disease from returning. An azalea that has suffered from disease needs restoration procedures no less than after a pest invasion or drying out due to poor care. The main goals are the same: restore immunity, improve conditions, help absorb nutrients.
The azalea must be replanted into new soil, making sure to check the condition of the roots. Then apply frequent watering and spraying with water containing boron and citric acid alternately, sometimes using Elina solution to strengthen the immune system.
It is important that at this time the air temperature does not rise above +20–22 degrees, and the lighting is soft without direct sunlight.
Video “Why does azalea wither”
From this video you will learn how to cure an azalea that has begun to fade.
