Brown spots spoil the beautiful decorative leaves and signal that your window leaf is not doing well. If the cause is not identified, brown leaves will inevitably die and fall to the ground. Use our tips on common causes and how to fix the problem.
What causes brown spots on Monstera leaves?
Brown spots on Monstera leaves can be caused by cold, eyespot, or sunburn. The remedy is to change location, remove infected leaves and treat with fungicide or sun protection with an awning on the balcony and move to a west or east window.
When it's cold, brown spots aren't far away
Your window leaf loves a warm, humid location with moderate lighting conditions. The exotic piece of jewelry cannot tolerate cold well, even for a short time. If the window is opened for a few minutes in winter to ventilate so that the temperature falls below 15 degrees Celsius, brown spots with a light edge will form. If Monstera are exposed to constant cold, brown leaves are the answer to this stress.
If you can diagnose the cause of brown spots and brown leaves as temperatures that are too low, changing the location will solve the problem. Sometimes it can be enough to stop tilting the window in the immediate vicinity of the window leaf during the winter.
Eye spot disease (Spilocaea oleagina)
If location problems can be ruled out as the cause of brown spots and brown leaves, diseases become the focus. It is often the eye spot disease that manifests itself with these symptoms. The fungal infection gets its name from brown spots with a light halo that visibly spread across the entire leaf. This is how the fight works:
- Cut off infected leaves and dispose of them in the trash can
- Disinfect the scissors with alcohol before each cut
- Treat renewed infection sites with a copper-based fungicide
- Treat the sick window leaf with Atempo Fungus-free from Neudorff or Cueva Fungus-free
Since the eyespot disease spreads very slowly, removing already infected leaves may be sufficient as a control measure. By regularly spraying the weakened window leaf with a decoction of horsetail or liverwort extract (€11.00 on Amazon), the immune system is strengthened. Only in cases of high infestation pressure is it necessary to use a fungicide containing copper.
Tip
A window leaf reacts to sunburn with light brown spots and a dark edge. Monstera species on the south window of living rooms or on the summer balcony are affected. Move the plant immediately to a partially shaded spot on the west or east window. An awning should filter the sunlight on the balcony.
