The apple tree is one of the most commonly cultivated perennial crops, both in professional horticulture and in the home kitchen garden or own orchard. Although the yield is actually considered quite safe, it happens again and again that the apple tree does not bloom. Which causes can be the reason for this and which help can still help the tree to blossom, we explain in the following in a simple and understandable way.
Causes and remedies
Of course, the reasons for the absence of flowering on the apple tree can be very diverse and even individual. However, in the majority of cases, the cause lies in one of the following recurring facts:
When apple trees are newly planted, most of their energy goes into establishing their own location. Only then is energy invested in reproduction through blossoms and apples. If a young tree needs all its energy for root formation, the blossoms are initially left out as an energy-saving measure.
- Origin: planting with a low root stock, or in soils that are difficult to root through; underplanting with nutrient competitors.
- Effect: Apple tree does not bloom because of insufficient nutrient supply
- Remedy: Keep tree disk free of underplanting, fertilize regularly
Plant too young
Like humans and animals, apple trees require a certain amount of time from germination to growth to reproductive maturity. In particular, grafted trees sprout flowers quite early, but even such a young apple tree usually does not bloom the year after planting. Plants grown from the core, as well as old varieties of Malus Domestica, on the contrary, can take up to six or more years to form flowers.
- Origin: natural stage of development
- Impact: no fruit yield until “sexual maturity”.
- Remedy: no remedy possible, waiting period for tree development biologically necessary
Even a high-yielding apple tree in its best years produces blossoms only in varying intensity. Certain varieties, such as Boskoop, Cox Orange, or Elstar, tend to be in profuse bloom in one year and produce no, or very few, blossoms in the second. The years without flowering represent a recovery phase for the tree, which on the one hand cannot be influenced and on the other hand should not be influenced, in order not to endanger the recovery phase.
- Origin: predisposition in the apple variety, trigger usually weather-related
- Effect: low-yield to yield-free years alternating with high-yield years
- Remedy: hardly any remedy possible
Tip: Although it is impossible to stop the alternation by an adapted pruning of the apple tree, a certain weakening of the alternating phases can be achieved. For example, in years when blossoms are weak or absent, growth-inhibiting pruning can be done to reduce the reduced blossom output as a result of heavy growth during these alternate phases.
Just as pruning can increase yield, incorrect pruning may cause the apple tree to fail to develop flowers the following year. If pruning stimulates too much growth, shoot formation may occur at the expense of flower formation.
- Origin: Removal of shoots bearing flowers in the following year, too strong stimulation of shoots due to incorrect pruning
- Effect: redirection of growth energy to new shoots instead of flowers.
- Remedy: moderate pruning of the right shoots
Wrong apple variety
More and more frequently, mass-grown intensive varieties from commercial fruit growing are also offered to hobby gardeners, for example the apple variety Braeburn. These varieties are grafted onto a weak-growing rootstock in order to thrive in extremely dense plantation cultivation. If such a tree now has room to develop in a private garden, it can only insufficiently fulfill the growth possibilities offered to it, so that the blossoms fail to appear in favor of the shoot formation.
- Origin: Wrong spatial possibilities for weakly growing intensive cultures
- Effect: redirection of growth force from the flowers to the shoots
- Remedy: growth-inhibiting autumn pruning
Nitrogen is one of the essential growth elements of all plants. Too much of this substance, on the other hand, leads to the stimulation of disproportionate growth of roots and branches. This sometimes manifests itself in such a way that the tree focuses on growth and no longer flowers.
Origin: oversupply of nutrients, especially nitrogen
Effect: too strong growth with neglect of flowering
Remedy: less and more targeted fertilizing, ideally soil analysis before fertilizer application
The visible consequences of a late frost are usually damage to already existing flowers or even fruit set. However, it is also possible that the first flower buds are already damaged by frost in such a way that the visible emergence of fully formed flowers is made impossible.
- Origin: intense frost after the flowers have started to form
- Effect: no development of the flowers due to preliminary damage in the budding stage
- Remedy: no remedy possible
Note: In the end, the late frost is not a real cause for the apple tree not blooming. This is because the blossoms are very much set, but only incompletely formed. However, since the effects for the observer are the same as with a completely absent blossom, this point should nevertheless be mentioned for the sake of completeness.
Weakness of age
Whether human, animal or plant, in old age the efficiency of the organism decreases. Reproductive capacity also suffers as a result. Thus, it can be a natural part of the aging process of an apple tree that the formation of blossoms stops when the growth capacity and the supply possibility through the roots decrease.
- Origin: natural aging
- Effect: tree no longer blossoms due to lack of nutrients and poorer supply
- Remedy: not possible
Tip: Through intensive care and optimal supply, you can delay the end of the flowering ability and thus also the fruit yield of aging apple trees. On the other hand, it is impossible to postpone it indefinitely or even to stop it completely!
Intensive pest infestation
If an apple tree is severely weakened by an excessive pest or disease infestation, it may shut down subordinate functions to save energy in order to protect the entire organism. Therefore, an intensive infestation can also cause the tree to bloom only slightly or even not at all in individual years. Once the infestation has been overcome, however, flowering performance in the following year is usually unimpaired.
Origin: Infestation by parasites, pathogens or other parasites.
Impact: restriction or absence of the flowering phase
Remedy: early control of the infestation, at the same time ensuring an optimal nutrient and water supply to strengthen the tree.
Caution: Depending on the type of pest infestation, individual shoots may be completely damaged so that no new blossoms appear despite overcoming the infestation. In these cases, a complete loss of the shoot can usually be assumed and it should be removed to strengthen the rest of the tree!