Heat and drought leave their mark on the home garden. If temperatures rise above 30 degrees Celsius, plants can quickly become sunburnt. What can you do if you have burnt leaves and flowers and how can you prevent sunburn?
How to recognize sunburn on plants: these are the signs!
The sunburn becomes noticeable quickly. Similar to humans, where the skin turns red, discoloration on the leaves indicates sunburn damage.
1. The leaves and flowers turn yellow or become completely white.
2. The burnt flowers and leaves curl up, turn brown, dry up and fall off.
3. The completely dried out edge of the leaf is often the first sign of sunburn.
Recognize sunburn on flowers and perennials
Plants develop yellow and wilted leaves even during long dry periods, pest infestations or certain care errors. How can sunburn be recognized?
- The affected plants have suddenly received more sunlight than usual in the last few weeks. With potted plants it is often due to a change of location. Sunburn often occurs with outdoor plants if the plants were recently shaded and are now suddenly in full sun.
- If the top leaves that receive the most sunlight turn yellow first, then it is sunburn.
- The lower leaves, which are shaded by the other leaves, mostly remain green. In contrast, when diseases and pests occur, the lower leaves turn yellow and wilt first, as they are strange entry points for bacteria and fungi in the soil.
Dry damage to trees and bushes
On trees and bushes you first notice burnt leaves, then flowers and then fruits. The fruit trees first develop round brown spots; on bushes, sunburn becomes noticeable through brown spots on the foliage.
Sunburn damage is often confused with signs of nutrient deficiency. The affected fruits, leaves and flowers wilt, dry up and then fall off. The burnt fruits are inedible and should be picked up and disposed of.
If the heat wave lasts longer than normal, sunburn can cause necrosis on the bark of young trees. A white coat helps against this. The white color reflects sunlight and prevents sunburn.
In contrast to potted plants and perennials in flowerbeds, changing the location of trees is out of the question. However, some of them can be protected from direct UV rays with shade nets.
Burnt leaves and flowers: what should you do?
If the plants already have burnt leaves and flowers, then you should try to save them and minimize the sunburn damage. Certain care measures can help:
Cut off damaged leaves, flowers and shoots
1. Burnt leaves and flowers are entry points for bacteria and viruses. So they should be removed immediately. It is best to cut off burnt items early in the morning or late in the afternoon.
Change location and adjust care
2. If possible, place the plant in a bright but sunny location. It is best to wrap large trees with shade nets.
3. Water early in the morning or late in the afternoon. Wet leaves are more susceptible to sunburn, so you should only water your plants from below.
4. Stop fertilizing for the next two weeks. The burned plants first need time to recover.
5. Do not change the watering. Sunburned plants no longer need water. Too much water can actually have the opposite effect - waterlogging forms, the roots rot and the plant dies.
Special case: Hydrangea burnt, what can you do?
If the hydrangea leaves yellow and dry from top to bottom, then it is most likely sunburn. The first rescue measure is to transplant young plants. Old and already woody hydrangea bushes cannot tolerate a change of location well. You therefore need privacy protection. The next step is to cut off the burnt leaves and shoots. Strongdamaged hydrangeascan be shortened by a third; they usually recover well from the caring cut. In the next few weeks the hydrangea will hardly be fertilized, but will be watered extensively from below.
Prevent sunburn on plants
Sunburn on plants should be prevented, especially during long heat waves. It is very important to act in a timely manner because the sensitive leaves and flowers can burn after just a few hours in the midday sun.
Sun protection for balcony plants
House and balcony plants in particular react very sensitively to full sun at 30° Celsius. Even true sun worshipers like the olive tree can burn. Hydrangeas in pots also often fall victim to strong UV rays.
To prevent this, you should place the potted plants in a sunny to partially shaded place when it is hot. It is optimal if you get the morning sun and are in the shade at midday.
The right place for houseplants
Houseplants that are on a sunny southern or western windowsill should also be moved to a new location. A coffee or side table that is close to, but not directly in front of, the window works well. This means the plants are bright without burning.
Shade nets for greenhouses and bedding plants
Some outdoor and balcony plants can only thrive in the summer with appropriate sun protection. Awnings and parasols are perhaps the best options for the balcony or terrace. The greenhouse or the shrub in the bed can be covered with shade nets. Each net has a certain percent shading effect. Shade nets with a 40% shading effect prove to be optimal for locations in full sun. This can be used to shade a greenhouse, bed or polytunnel.
Sunburn on plants: the most important things summarized
When temperatures exceed 30 degrees in summer, not only people and animals suffer, but also garden plants. Trees, shrubs and flowers that are in the sun often get sunburned in hot and dry conditions. To avoid this, you can shade the plants or place them in a sunny place. In addition, regular watering is very important so that the plants can withstand this period without any problems.
If the plants have burnt leaves, flowers and fruits, they should be removed quickly. They are entry points for bacteria and fungi. Fertilizer applications will be stopped over the next few weeks until the plant has completely recovered. Water the plants slowly and only from below so that no water can get onto the cut edges or the leaves.
