Rhododendron grows, but does not bloom - that's how they help it

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Rhododendron grows, but does not bloom - that's how they help it: they

Decorative, sumptuous and easy to care for - Rhododendrons are now among the most popular plants that grow within the local green area. The plant, which is almost all over the world depending on the variety, is characterized by its lush flowers - which is particularly noticeable when the rhododendron once stops its flowering. For the flowering laziness of rhododendrons, however, quite different causes can be considered.

Determine cause of blooming laziness

In order to be able to specifically help the plant to develop flowers, the cause of the flowering laziness must first be determined. Often, nursing mistakes are guilty; In some cases, however, location problems or pests can be the trigger for the difficulties in flower formation. Overall, the following causes of this phenomenon can be identified:
  • 1. Inappropriate location
  • 2. unsuitable substrate
  • 3. unfavorable nutrient distribution
  • 4. Pruning at the wrong time
  • 5. Pest infestation
  • 6. unfavorable weather conditions
To clearly determine why rhododendrons do not flower, hobby gardeners need to know about the symptoms and circumstances that still cause the individual causes besides blooming laziness.


Most hobby gardeners are aware that rhododendron is a forest plant - and choose shady areas within its own green area as a location. However, when the plant is placed in the deep shade, flowering is usually severely limited or even completely absent, while the plant as a whole continues to grow. Above all, the leaf formation is pronounced in an unfavorable position of the rhododendron, because the leaves ensure that as much as possible sunlight is captured. The hobby gardener should first look at the location of the plant and its leaf formation.


Finally, if it turns out that the wrong location is actually the cause of the lack of flowering, a brighter place should be sought immediately. It is important that the Rhododendron receives at least both in the morning and in the evening for a few hours each direct sunlight. Even more flowering is the plant, if a full day light shading is guaranteed - for example, by trees with bright crown. In this context, especially the local Scots pine has proven to be an ideal shade donor. In addition, the hobby gardener can provide a stronger light incidence by cutting back the plant and clearing the crown.


If the rhododendron does not flower, the choice of an unsuitable substrate can be the trigger. Under natural conditions, the plant is used to soils with the following characteristics:
  • pure humus soil
  • thick raw humus layer on the topsoil
  • Raw humus consists of slightly decomposed foliage
  • mineral subsoil
  • Plant roots are hardly fused with the subsoil
If the rhododendron has been cultivated in a substrate that has only a small proportion of humus, this may also affect the flowering activity; Here again the entire plant is to be considered. Although plants fail to flower due to the wrong substrate, they grow in their entirety - but very slowly. In addition, they only form sparse foliage. Rhododendron, despite a small proportion of humus in the soil, is still able to handle quite well if it is a sandy substrate; However, if there is a cohesive loamy soil or loess soil, the symptoms mentioned appear more clearly. The sensitive roots of the rhododendron are then unable to penetrate the fine-pored soil; they suffocate.
Anyone who has identified a substrate with an unfavorable composition as the cause of the flowering laziness of the rhododendron should either offer the plant a more favorable location with humus-rich soil or enrich the substrate. For this purpose, the rhododendron must first be planted out and then buried again in the ground.
Tip: If the rhododendron is re-used and then still does not form flowers, this is probably due to a stress response that involves transplanting. Then it is important to wait, because in the following year the plant will most likely bloom again.


If the rhododendron is in a suitable place and also contains the soil sufficient humus, even a wrong nutrient supply of the plant may be responsible for a non-existent flowering, for example:
  • too large quantities of fertilizer
  • too small quantities of fertilizer
  • the wrong composition of the fertilizer
Especially if too much fertilizer is used or the components of the nutrient mixture are not adapted to the special needs of rhododendrons, the plant can quickly become lazy. The hobby gardener recognizes the fertilizer problem also because the plant looks healthy overall and also grows very well; then mostly fertilized on one side with a mineral nitrogen fertilizer, which promotes the vegetative growth of rhododendrons and inhibits flower formation at the same time. The same effect can occur if the phosphate content in the fertilizer is too low - and at the same time other important substances are missing, for example potassium.


Above all, the optimal ratio between potassium, phosphate and nitrogen is decisive. Special rhododendron fertilizers are tailored to the needs of the plant and are also available in the long-term version; Anyone who resorts to such products provides their plants with a perfect fit and stimulates them to flower again. Hobby gardeners, who pay attention to organic horticulture, resort to organic solutions. If sufficient phosphate and potassium are present in the soil, it may also be sufficient to fertilize the rhododendron with horn shavings.
Tip: If the nutrient supply can no longer be determined, it may be useful to carry out a soil survey.

To cut

If the rhododendron does not flower, it may also be related to a pruning that the hobby gardener may have done at the wrong time. When pruning is to be noted:
  • Rhododendron form their flowers already in the previous year.
  • This process will be initiated immediately after completion of the flower season.
  • The scissors is so to start when the faded parts are being removed.
However, many hobby gardeners do not cut the rhododendron directly after flowering, but in spring - together with shrubs and shrubs. But then most of the flowers will be removed at the same time. In order to avoid a failure of the flowering by the wrong time of the pruning, the hobby gardener should fix the scissors in the period between July and November. An exception are Late flowering varieties, such as Cunningham's White, which can be cut back even in the spring.

Pests and diseases

Last but not least, pests or diseases can be the reason that the rhododendron does not bloom. However, in this case, the plant additionally shows other symptoms, by means of which infestation is clearly recognizable. The dreaded rhododendron cicada, for example, presents the following image:
  • gray-black discoloration of the flower buds over the summer
  • Drying of flower buds
  • Formation of a thin, moldy, black coating
  • Buds are eventually killed
The pest lays its eggs in the bud scales of the plant during its summer; then the bud is infected at the injection site. Once the rhododendron is infected, control is difficult. The affected buds must be removed immediately and then disposed of with household waste. Until the end of May, the pests can be combated with suitable insecticides. The large-flowered hybrids are particularly susceptible to the rhododendron cicada - although there are large differences depending on the variety. Insensitive:
  • 'Goldbukett'
  • 'Berlin love'
  • 'Le Progres'
  • Yakushimanum hybrids

weather conditions

Finally, one more reason for the blooming laziness of the rhododendron is called against the even the most experienced hobby gardener can do nothing; These are unfavorable weather conditions. In recent years, there have been more and more frequent temperature increases in our latitudes, which have presented themselves as unusually mild winters, for example. If it is too warm for a long time during the cold season, the buds of the rhododendron open prematurely - which can then cause them to freeze before flowering. Then only helps to hope for the following year.


Overall, however, shows that most causes of flowering laziness of rhododendron can be influenced; then it is important to find out exactly which care mistakes have led to a limited flowering - to correct them as soon as possible. Anyone who pays attention to his plant and deals thoroughly with it, will find the cause quickly - and can soon be happy again about many beautiful flowers on rhododendron.

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