If the blossoms of tomatoes suddenly fall off, there are various possible reasons for this. We will show you which triggers are responsible and what you can do about it.
Table of Contents
Blossom shedding due to lack of fertilization
Tomatoes have hermaphrodite flowers. This enables them to carry out fertilization independently. For this reason, tomato plants generally do not need insects to take over this part. However, lush flowering is by no means a guarantee of a rich harvest. A few basic conditions are necessary so that fertilization actually takes place and tomato fruits develop. If these are missing, the hoped-for harvest fails to materialize. If the tomato blossoms are not pollinated within a few days, they will fall off.
Missing movement
With outdoor tomatoes, the wind moves the flowers, causing the pollen to fall on the pistil. In closed greenhouses and on the windowsill, however, there is usually no wind.
countermeasures
In windless locations you can achieve the movement necessary for pollination by shaking. The vibration caused by the pinching of the shoots is often enough.
Missing Insects
Although insects are not absolutely necessary for the pollination of tomato flowers, their presence has a positive effect on the fertilization rate.
remedy
Flowering plants in the immediate vicinity are perfect for attracting bumblebees, bees and the like to the tomato bed. This includes:
- Fruit trees and shrubs such as apple, pear, raspberry and blackberry
- Summer flowers (sweet nettle, lavender, sunflower)
- Hedge plants such as elder, hawthorn or wild rose
- Climbing plants (wisteria, ivy or climbing hydrangea)
- Herbs such as St. John’s wort, sage or thyme
unfavorable temperatures
Tomatoes are very sensitive to both extremely hot and dry weather and sudden cold weather. When this happens, the plant sheds its buds to focus on its own survival. The so-called old varieties, which are popular with gardeners, are particularly affected. Temperatures also play an important role in fertilization. If these are over 20 degrees at night or under 12 degrees, or over 30 degrees during the day, the pollen becomes sticky and is not viable.
countermeasures
Provide balanced culture conditions with moderate temperatures and slightly higher humidity. You can achieve this by shading the greenhouse or outdoor tomatoes. If cool night-time temperatures are predicted in late spring or early summer, it is best to protect your plants with a film or a so-called tomato house.
Unfavorable humidity
Another reason why the tomato flowers fall off unfertilized can be too high or too low humidity. If it is too dry, the pollen will not be able to adhere to the pistil. If the humidity is too high, it sticks strongly and does not detach from the stamens. A relative humidity of between 40 and 70 percent is ideal. It is therefore worth installing a hygrometer in the greenhouse
Loss of flowers due to lack of nutrients
A balanced supply of nutrients is not only important for the growth and health of the plant, but also for its flowering. Tomatoes are among the heavy consumers, but too many nutrients are just as harmful as too few.
nitrogen deficiency
When the blossoms of tomatoes fall off, the cause is often an unfavorable nitrogen content in the soil. If there is too much nitrogen, the tomato prefers to put its energy into leaf growth and very little flowering takes place. Too little nitrogen results in thin shoots that are unable to adequately nourish the fruit.
Phosphormangel
If numerous tomato blossoms suddenly fall off, a lack of phosphorus can also be responsible. You can easily recognize a phosphorus deficiency if you take a closer look at the leaves of the plants. If there are bluish to purple discolorations on the foliage, there is a high probability that the plant is lacking in phosphorus.
Potassium deficiency
The cause of the tomato blossoms falling off and brown spots on the fruit can also be the so-called blossom end rot. Blossom end rot is not a disease, but a deficiency. The tomato lacks the nutrient potassium.
Countermeasures against nutrient deficiency
If the flowers are already falling, rock dust that you work into the soil at the root ball will help. However, it is better to work plenty of ripe compost into the future tomato bed in spring so that there is no shortage in the first place. As a rule of thumb, per square meter or plant:
- 3L mature compost
- 150 g horn shavings or horn meal
- a handful of rock flour
lack of water
To avoid stress for the plant, the root ball should always be slightly moist. It is also important that the roots have enough space. If the plants are too dense or in a cramped pot, the supply of water and nutrients is limited. As the first sign of a lack of water, the leaves curl up and the flowers fall off. Later, the entire plant may wither away.
- Minimum distance: 60 to 100 cm
- Pot size: at least 20 liters per plant
Diseases
Diseases or pests that cause the flowers to fall off are common in tomatoes . In most cases, however, not only the tomato blossoms are affected, but the whole plant. These include, for example, brown rot or powdery mildew. However, there is a bacterium that only affects tomato flowers. The Xanthomas bacterium preferentially occurs in humid, cool summers. The infection can be recognized by the following characteristics:
- black-grey, dead flower
- yellow transition to stem
Countermeasures
Once the tomato plant is infected, hardly any remedy will help. It is therefore important to pay attention to optimal site conditions in advance. This includes a sufficient distance so that the leaves can always dry well. The best way to protect your tomatoes against disease is to plant them in a tomato house.
frequently asked Questions
So-called outdoor tomatoes are less susceptible to diseases and heat or cold stress. Not only are they resistant to brown rot, they are also very weather tolerant. These include: ‘Black Plum’, ‘Golden Currant’, ‘Lily of the Valley’ and ‘Sparta’.
If flowers have been on the plant for a few days, grasp the base of the stem with your hand and shake it gently. The chances of fertilization are best on a sunny day around noon. Since not all buds mature at the same time, you’ll need to repeat the process every few days.
