If you are like me, you love your Monstera. The beautiful, glossy leaves and its unique appearance make this plant a fantastic addition to many homes. That is why I started to slightly panic when I saw that the leaves of my Monstera were starting to turn yellow. I was not completely sure why this was happening, so I did a some research. After extensive research, I found that there are several reasons why the leaves of your Monstera are turning yellow.
The most common cause of yellow leaves is overwatering. Improper fertilization, underwatering, inadequate light, pests, transplant stress, and low humidity levels can also cause Monstera leaves to turn yellow. However, yellow leaves are not always a cause for concern. It is normal for some of the older, lower leaves of the plant to turn yellow and die.
The rest of this article will be a detailed discussion of why leaves turn yellow and what you can do to correct some of the problems that could be causing the leaves of your Monstera to turn yellow.
Why do leaves turn yellow?
So why do plant leaves turn yellow? Leaves turn yellow when chlorophyll, which is the pigment responsible for making leaves green, is lost from the leaves. Leaves contain pigments besides chlorophyll, but chlorophyll typically masks these pigments. For example, carotenoids are responsible for the yellow color of autumn leaves.
The inability to produce adequate chlorophyll is often referred to as chlorosis. Signs of chlorosis include:
- New growth will be lighter in color with dark green veins.
- Established growth will be a normal green color.
There are other things (besides chlorosis) that impact the amount of chlorophyll and cause leaves to turn yellow. For example, pests and diseases can block vascular bundles in plants.
How Overwatering Your Monstera Causes Yellow Leaves
Overwatering is the most common killer of indoor houseplants and is a common reason that leaves turn yellow. This is because saturated soil hinders a plant’s ability to take up nitrogen from the soil. A dip in nitrogen can cause decreased levels of chlorophyll. This is because chlorophyll content is approximately proportional to the nitrogen content in leaves (Evans, 1983).
If a Monstera’s leaves are turning yellow due to overwatering, the lower leaves will be affected first.
Wet leaves can also attract fungus gnats. These pests can cause the base of stems to turn black.
Ironically, overwatering adversely impacts a plant’s ability to absorb water from soil. This is because too much water can drown the roots and cause them to die. As a result, the roots are no longer able to absorb water and associated soil-derived nutrients for the rest of the plant. For this reason, overwatering can cause wilting and other symptoms that make it appear that the plant is underwatered.
Keep in mind that your Monstera probably goes dormant during the winter. I say probably because the conditions in some people’s home allow for these plants to grow year round. However, for many people, shorter days may trigger a dormant period during the winter months. During this time, growth will slow down, and your Monstera will not need to be watered as often.
To avoid overwatering, it is very important that your Monstera is planted in a container that allows excess water to drain away. Make sure that you plant your Monstera in a pot with drainage holes. Otherwise, water will pool at the bottom of the pot and potentially cause root rot.
In addition, make sure that your Monstera is planted in well-draining soil. If you are having problems with overwatering, I recommend trying Al’s 5:1:1 potting mix which consists of the following:
- 5 parts pine bark
- 1 part coarse perlite
- 1 part peat
- 1 Tbsp of garden lime per gallon of soil
- Time-release fertilizer (optional)
How Underwatering Your Monstera Causes Yellow Leaves
Just as overwatering can cause Monstera leaves to turn yellow, underwatering can also cause yellow leaves.
A water shortage that impacts a plant’s ability to take up water can also cause leaves to turn yellow. Normally, water enters the root system and is delivered to the leaves through the process of transpiration. The water delivered to the leaves also contains soil-derived nutrients that the plant needs to photosynthesize. When there is a water shortage, it can be difficult for the plant to get the nutrients it needs to produce chlorophyll and photosynthesize. The lack of chlorophyll causes the leaves to turn yellow.
Other signs of underwatering include wilting leaves or a droopy appearance. Unlike overwatering, underwatering often results in leaves that have yellow and brown spots.
To ensure that you are giving your plant enough water, check the soil frequently. Water your Monstera after the top 2-3 inches of soil completely dries. When you do water your Monstera, water the plant thoroughly until water is flowing out of the drainage holes.
Some people use soil moisture meters to help them determine when plants need to be watered. Although high-end soil moisture meters can accurately determine soil moisture reasonably well, low-end soil moisture meters tend to be wildly inaccurate.
I am not saying that soil moisture meters are completely useless. However, they are not a substitute for checking the top few inches of soil.
Improper Fertilizing Your Monstera Can Cause Yellow Leaves
If your Monstera lives outside, it probably does not need to be fertilized. However, Monsteras grown indoors need to be fertilized regularly in order to replace the nutrients depleted from the potting soil.
Yellow leaves or yellow/brown splotching can be a sign that your plant needs more fertilizer. Yellow leaves can indicate a deficiency in nitrogen, magnesium, iron, and zinc. Monsteras will lose their holes or slits if they need more fertilizer or light.
Nutrient deficiency can also be associated with soil pH. This is because soil pH impacts the availability of nutrients. Your Monstera should be growing in soil with a pH between 5.5 and 6.0.
Similarly, yellow leaves can be a sign of too much fertilizer. Salt deposits on the pot or evidence of leaf burn are indications of excess fertilizer.
Pests Can Cause Monstera Leaves To Turn Yellow
Soft-bodied, sucking pests such as spider mites, aphids, and mealybugs can also cause leaves to turn yellow due to excessive sap removal. These insects pierce the leaf tissue and extract plant fluid from the leaves. This causes yellowing because removing this “plant juice” disturbs the plant’s ability to regulate its transpiration and water retention.
Low Humidity Levels Can Cause Monstera Leaves To Turn Yellow
Monstera is native to the tropical regions of Costa Rica, Guatemala, and Panama. As you might expect, these areas tend to be very humid – much more humid than our homes. Although Monstera can typically tolerate the drier conditions in most homes, sometimes the lower humidity can cause the leaves to turn yellow.
To increase the humidity in the vicinity of your Monstera, consider purchasing a plant humidifier. In addition, you could group plants closer together or place a pebble tray (tray full of pebbles and water) near your Monstera.
Inadequate Light Can Cause Monstera Leaves To Turn Yellow
Inadequate exposure to light can also cause the leaves of your Monstera to turn yellow. If the plant is unable to absorb enough light, the plant will not be able to produce chlorophyll. As a result, the leaves lose their green coloring.
Other signs that your Monstera is not getting enough light include the plant losing its holes/slits and “stretching.” Monsteras exhibit negative phototropism which means they grows toward darkness when they need more light. This may seem counter intuitive, but in the wild, Monstera grows toward trees that it could climb up. In tropical forests, darkness tends to indicate stands of trees.
It is also important to clean the leaves of your Monstera on a regular basis. Otherwise, a thin layer of dust will form and block the plant’s ability to absorb light and photosynthesize.
Transplant Shock Can Cause Monstera Leaves To Turn Yellow
Transplant shock is a term that refers to a number of stresses that result from repotting a plant. Leaf scorch is a common symptom of transplant shock, and it manifests as bronze and yellow leaves.
To prevent transplant shock, make sure that you are providing the plant with the best environment you can. When you water, use tepid water rather than water that is too hot or too cold. Finally, do not fertilizer your month for a month or two after repotting. This will give the roots time to acclimate to their new environment.
Old Leaves Turn Yellow
Yellow leaves are not always cause for concern. As plants age, leaves will eventually turn yellow and fall off.
When leaves grow old, the chlorophyll in the leaves degrades. However, xanthophyll degrades more slowly than chlorophyll and will remain in the leaf after the chlorophyll is gone. Xanthophyll is a type of carotenoid pigment and gives the leaves a yellow appearance.