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A few yellow leaves on the nasturtium are normal. If more leaves are discolouring, this is an alarm sign that the plant is not doing well. Simple measures bring the color back.
In a nutshell
- a few yellowing leaves are a normal part of the aging process
- check for possible causes only when yellow leaves accumulate
- too much or too little water can lead to yellow leaves
- if over-fertilized, the leaves turn yellow
- Pests like aphids can cause yellow leaves
Natural aging process
The nasturtium (Tropaeolum) is now available in different variants as a ground cover or climbing plant. It shows its yellow to orange flowers from around June until frost. During this time, the foliage should also be nice and green. Nevertheless, it can happen that it has single yellow leaves. This is not yet an alarm signal, but part of the natural aging process of the plant. Older leaves die off because it takes too much effort for the plant to maintain them. The plant also separates leaves that get too little light or are damaged, and they turn yellow and eventually fall off.
Notice: You can support the plant by removing leaves near the stem that are beginning to turn yellow. This means that the plant has to invest less energy in this decomposition process.
water supply
There are many reasons why the leaves turn yellow. The most common reason is the supply of water. Nasturtiums react to both too much water and too little water with yellowing of the leaves. It is easy to determine whether there is too much or too little water. If you water too much, the leaves at the bottom tend to discolor first. The leaves in the lower area are also at greater risk of infections such as mold due to too much water.
If the yellow leaves result from a lack of water, you can recognize this by the following characteristics:
- yellow leaves in the upper area (shoot tips)
- Leaves hang limp
- Leaves partially curl up
You can easily prevent a lack of water or waterlogging when planting. To do this, mix the soil with clay granules or expanded clay. This loosens the soil, but can also store water very well at the same time, which is gradually released into the environment.
Too much fertilizer
The nasturtium often reaches impressive sizes, which is why many hobby gardeners suspect that it has a high nutrient requirement. It does need nutrients and more than herbs usually need, but it is not a heavy feeder. In terms of consumption, it is more in the lower range of medium consumers. However, too much fertilizer causes the leaves of the nasturtium to turn yellow and drop them.
If the yellow leaves are the result of over-fertilization, do the following:
- Stop fertilizing immediately
- Water more, but do not create waterlogging
- if possible transplant to a nutrient-poor location
Watering is an easy way to reduce the concentration of nutrients in the soil. However, you should pay attention to the right time here. The right time for watering is late morning. At this time, the risk of waterlogging is also low, because the sun dries out the soil again during the day.
Tip: If the nasturtium is cultivated in a pot, simply change the substrate. Be sure to remove as much of the over-fertilized substrate as possible without damaging the roots too much.
However, you must not completely do without nutrients, otherwise yellow leaves can form due to an undersupply. If you plant the nasturtiums in spring, mix a substrate with a medium concentration of nutrients. This consists of the following parts:
- 3 parts garden soil
- 2 parts compost (sifted)
- 1 part sand
Many are tempted to take care of the nasturtium by giving liquid fertilizer. However, this should largely be avoided. Above all, you must not use fertilizers that have a high nitrogen content. You can work in a maximum of some compost around the plant during the course of the season.
aphids
Although nasturtiums are well protected against diseases and pests due to their ingredients, they are not completely spared. A common problem on these plants is aphids. They are usually particularly difficult to discover or are not found for a long time, as the large, round leaves offer optimal privacy for the lice.
The lice injure the leaves with their mouthparts. The plant can still compensate for a few spots, with a heavy infestation the leaves discolour and are then discarded. However, this is often a vicious cycle, with the aphids then crawling back onto the plant and causing further damage there.
You can easily fight this:
- Remove heavily infested leaves and dispose of in the residual waste
- Wash off lice with a soft soap solution (1L water and 2 tablespoons curd soap).
- Promote beneficial insects such as ladybugs
- Strengthen the epidermis of the plant with manure (horsetail).
Tip: Occasionally look at the underside of the leaves. In this way you can discover early on whether aphids have infested the plant.
frequently asked Questions
Don't manure make sure you have an additional supply of nitrogen?Not all manure has a high proportion of nitrogen. Horsetail strengthens the plant's epidermis, but is low in nitrogen. As an alternative to liquid manure, you can also use broths or teas that contain little or no nitrogen.
How often should nasturtium plants be watered?In the short term, nasturtiums cope well with drought. If the dry phase lasts longer, they should be watered thoroughly every three to five days.
Does the harvest favor the formation of yellow leaves?No, neither cutting off the flowers nor the leaves promotes yellowing. Only remnants of leaf and flower stalks turn yellow and fall off. Therefore, you should always remove leaves and flowers close to the main shoot.