Evergreen rhododendrons, or rhododendrons, are a picturesque accent that enlivens the garden. They look beautiful in groups, and their flowers please the eye from May to June. However, it often happens thatrhododendron does not bloomThis problem is usually related to errors in the cultivation and care of these plants. Find out about the 7 most important reasonswhy rhododendron does not bloomand learn how to fix them to fully enjoy the beauty of blooming rhododendrons.
Why is the rhododendron not blooming? See what to do to make it bloom like the one in the photo!
1. Rhododendron does not bloom because it grows in too alkaline soil
Rhododendrons do well in acidic, well-drained soils. The alkaline pH of the soil is often the reason forthe lack of flowering of the rhododendronsand the poor appearance of the plant. The appropriate pH is in the range 4.5-5.5.
The low pH level ensures proper digestibility of nutrients by rhododendrons. We can obtain it by adding acidic garden peat, composted pine bark or one of the ready-made preparations for acidification of the substrate available on the market. When planting, it is worth digging a larger hole, covering it with an acidic substrate and then placing the plant on the prepared substrate. Sprinkle the planted rhododendron with pine bark mulch. It will protect the shallow root system against drought, frost and weed infestation. In addition, it will help maintain the proper pH of the soil, which is so important in the cultivation of these plants.
In the following years of rhododendron cultivation, it is recommended to apply acidifying fertilizers in order to maintain a sufficiently low soil pH.
2. Rhododenron does not bloom because it has too little sun
A semi-shade position is recommended for most large-flowered rhododendrons, because in full shade, theserhododendrons do not bloom , and their leaves are exposed to sunburn in full sun. Unfortunately, we often exaggerate with this shade. Therefore,when the rhododendron is not bloomingmake sure the position is shaded but only partially. To obtain partial shade, rhododendrons can be planted under taller trees such as pine and fir, where the root system of the trees will not compete with the rhododendron roots.
There are, however, exceptions to this rule. And so, among the large-flowered rhododendrons there are varieties such as 'Catharine von Tol', 'Cunnigham's White' and 'Torero', which grow well in full sun.Small-flowered rhododendrons with small evergreen leaves and varieties from the Yakushiman rhododendron group also feel great in full sun exposure. In these rhododendrons, greater sunlight will always contribute to better flowering, and at the same time will not harm their leaves.
3. Rhododenron won't bloom due to poor fertilization
The fertilization of rhododendrons should be moderate. Too abundant doses may adversely affect the plant. You should limit fertilization to two doses. The first one, at the beginning of the growing season, is to stimulate the flowering process. The next one, given in the summer, will allow you to properly set the buds for the next season.
If we fertilize rhododendrons frequently with nitrogen, we will cause abundant leaf production, lush growth, butthe rhododendron will not form flower budsand not will bloom. That is why it is worth reaching for superphosphate, a fertilizer rich in phosphorus, which will stimulate the plant to flower. For top dressing, one should also use physiologically acidic fertilizers, such as sulphate forms of ammonium, potassium and magnesium. Of course, any multi-component fertilizers designed specifically for rhododendrons and acidophilic plants will also be good. However, alkaline mineral fertilizers, such as calcium nitrate, calcium ammonium nitrate, should be avoided, as they will increase the soil pH, which is unfavorable in the cultivation of rhododendrons.
4. Rhododendron does not bloom because faded inflorescences have not been removed
After the rhododendrons have flowered, it is important to break off the remains of the inflorescences, thus preventing the setting of seeds. The procedure of removing blown inflorescences encourages the rhododendron to continue blooming. Remember to break out the faded inflorescences, and not cut them out with a pruner. To do this, grab each inflorescence at its base with your fingers and gently break it off. In this way, we mimic the natural process of a faded inflorescence collapsing, without leaving wounds after cutting. The job is quite tedious, but its results reward the effort. The plant, freed from the need to produce seeds in this way, devotes all its energy to creating new flower buds that will bloom next year.
5. Rhododendron does not bloom because flower buds are frozen in winter
Rhododendron produces flower budsin summer and they bloom next spring. When the winter is cold and windy, they can freeze. It happens when we choose the wrong cultivation position for the bush. It should be semi-shaded, quiet and sheltered from frosty, drying winds (such winds occur especially from the east). You should also remember to properly protect the plant for the winter, cover it with agrotextile or coniferous branches. When rhododendron leaves become saggy in winter, which is a sign of lack of water, it is worth watering the plants during the thaw.
6. Rhododendron does not bloom due to fungal disease
One of the fungal diseases that damagesrhododendron flower budsis gray mold. It is caused by the fungus Botrytis cinerea. The first symptom is brown spots that dry over time and form a grayish, dusty coating on their surface.High humidity and temperatures above 15 ° C promote infection. To prevent gray mold, avoid over-thickening of plants and cut out heavily infested shoots. Fight the fungus after noticing the first symptoms with Switch 62.5 WG or Signum 33 WG preparations. Repeat the spraying 3 times at intervals of 7-10 days.
Anotherfungal disease affecting the rhododendron budsis bud dieback. This disease is caused by the fungus Pycnostysanus azalea. Its characteristic symptoms are shrunken flower and leaf buds, which darken, and with time a tarnish can be seen on their surface. Consequently,rhododendron does not bloomThe disease is transmitted by the jumper Graphocephala coccinea. Infected buds should be removed.
7. The rhododendron is not flowering as the flower buds attacked the aphids
Colonies of aphids appear on young shoots in spring. As a result of their feeding, the shoots are weakened, andrhododendron does not bloomHeavily infested bushes die.The presence of aphids can be recognized by the honeydew on the plant - honey dew. Aphids are vectors for many viral diseases and therefore need to be combated. After observing the first colonies, spray with plant protection products such as: Mospilan 20 SP, Karate Zeon 050 CS, Fastac 100 EC. blooming
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