Monstera: what to do with brown/black spots?

cold

The windowsill is at home in the tropical rainforests of Central and South America. Pleasant temperatures between 25 and 30 degrees Celsius and high humidity prevail there all year round. If the Monstera is too cold, it initially develops brownish to black spots. If the air is too dry, the tips of the leaves will turn brown. Do you suspect that your window leaf is suffering from the cold? Then use a thermometer to measure the temperature in its immediate vicinity.

In the months between April and October, the room temperature should ideally be between 20 and 28 degrees Celsius. In the second half of the year, when it is darker outside, it can also be a bit cooler at the location. Between October and March, the exotic grows only a little, which is why temperatures around 20 degrees Celsius are completely sufficient. Under no circumstances should it be cooler than 16 degrees Celsius. Make sure that the plant is not exposed to any drafts or temperature fluctuations when airing, as this also causes leaf discoloration.

Blazing sun/heat

But not only cold, but also heat or blazing sun cause unsightly leaf spots. Intense solar radiation literally burns brown or black holes into the large leaves. The window leaf thrives in the protection of the great jungle giants in the middle of the rainforest, where it is bright but not directly sunny. Therefore, the plant feels most comfortable in a bright location without direct sun. To avoid stains, the Monstera

• do not stand in the blazing sun
• preferably not on a south-facing window
• be protected from the intense midday sun

East- or west-facing windows are ideal, as they usually only let in direct sunlight in the morning or afternoon. If you place your window leaf on the balcony or terrace in summer, it makes sense to protect it at midday. An awning, for example, prevents leaf burns.

Dark location

Although the window leaf can be a little more shady, too little sunlight also leads to unwanted discoloration of the leaves. The fact that your plant is too dark is initially shown by the missing or only weakly pronounced indentations or indentations in the leaves. These are now only weakly developed or even non-existent. The yellowish to brownish leaf discoloration comes a little later. In addition, weak growth and noticeably small leaves indicate a lack of brightness. Typically, these also have a darker shade of green than specimens that are lighter.

In this case, only a change of location will help. Place the Monstera in a spot that is not directly sunny but is as bright as possible near a window. However, this should be one and a half to two meters away, since the plant has to stand freely in the room. For example, if the leaves come into contact with window panes (which can get very hot in summer and freezing cold in winter), this will result in brown or black spots on Monstera leaves. If such a location is not available, install a plant light directly above the plant that provides the desired light intensity.

fungal infection/eye spot disease

In addition to an unsuitable location, the wrong temperature or incorrect care, the Spilocaea oleagina fungus can also cause brown or black spots on the leaves. The infection shows itself through a typical damage pattern:

• spots are round and light brown on the inside
• Edge is slightly darker, lighter in the middle
• Rest of the leaf is often tinged yellow
• later complete brown to black discoloration of the leaf

This disease is also known as eye spot disease or peacock eye, since the leaf spots remind the viewer of eyes. Affected leaves should always be removed, otherwise the spores will spread to other leaves. Combat eyespot disease as follows:

• If the infestation is severe, cut back the plant completely
• strengthen with horsetail stock or liverwort extract
• use sharp and disinfected scissors to remove infested leaves
• then disinfect them again in alcohol
• Dispose of clippings in household waste, never in the compost

As a rule, the Monstera recovers and soon drives out again.

discoloration of entire leaves

If Monstera leaves are turning full color rather than spotting, it’s likely due to one of the following causes.

Frequent watering/waterlogging

The exotic plant does not tolerate “wet feet”, as waterlogging is often called, and reacts to this with brown, dried-up leaf discolouration. This sounds paradoxical at first, but it is not. Wet soil causes the roots to rot over time, so that they can no longer absorb water and nourish the above-ground parts of the plant. This is how the foliage dries up, although apparently there is enough moisture.

How to save your window leaf:

• repot and transfer to fresh substrate
• remove rotting roots and wet substrate
• no more watering

drought stress

But be careful: Even too little water can lead to unsightly stains on the leaves of the Monstera. When there is a lack of water, the leaves first turn yellow , later they become brownish wither and finally die. How to water the plant properly:

• water weekly and abundantly in summer
• moderately every two weeks in winter
• drain excess water
• Pot drainage made of clay granulate
• Spray the plant regularly
• do a finger test before pouring

In addition, you should never water the window leaf with cold water straight from the tap. Let the fresh water stand for a while or run it through a filter: it should be as lukewarm as possible and low in lime.

over-fertilization

As a rainforest plant, the Monstera is quite frugal, a lack of nutrients is usually not indicated by spots on the leaves – an oversupply, caused by over-fertilization, however, is. This helps:

• transfer to fresh, unfertilized substrate
• between April and September fertilize at most every two weeks
• alternatively use long-term fertilizer
• Use green plant fertilizer
• do not fertilize between October and March

When fertilizing with liquid fertilizer, make sure that the leaves are not wetted.