This article may contain affiliate links. We get paid a small commission from your purchases. More Affiliate Policy
While it can cause distress, leaf yellowing (chlorosis) on your Swiss cheese plant (or other aroids) can only have a handful of causes – generally related to plant care.
Chlorosis, the abnormal yellowing of leaf tissue, typically begins as lighter green tissue between darker green leaf veins. Chlorotic leaves are more vulnerable to leaf diseases and burning. If left untreated, the afflicted plant may die from chlorosis or its cause.
Table of Contents
- 1. Monstera Root Health
- 2. Nutritional Imbalance – Causes of Yellow Monstera Leaves
- 3. Monstera Environmental Stressors – Cause of Yellow Leaves
- 4. The Relationship between Light and Fertilizer
- 5. Monstera Pest Infestations
- 6. Bacterial and Fungal Infections in Monstera
- 7. Soil pH and Iron Availability
- 8. High Temperatures and Drought
- 9. Natural Causes for Monstera Yellow Leaves
- Summary to Yellowing Monstera Leaves
This article explores, in some depth, the nine possible causes for chlorosis in Monstera, knowledge that is equally applicable to philodendron and pothos.
1. Monstera Root Health
Because root health (or the lack thereof) is the most common cause of yellowing leaves in aroid plants (plants that belong to the Araceae plant family), I list it first. Yellowing leaves are usually (but not always) a symptom of underlying root distress.
Healthy soil is soil that provides an environment in which plant roots can thrive. Access to moisture, air, nutrients, and symbiotic relationships with microorganisms contribute to a healthy growing environment.
The balance between moisture and air availability is essential to effective soil. Other soil factors include:
- Nutrient management – an ability to store and release essential plant nutrients
- The most undervalued attribute – a hospitable environment for soil microorganisms
- Plant requirements for acidic or alkaline soil (pH requirements)
- Plant anchorage – ensuring the media isn’t so light that the plant cannot remain reasonably erect as it grows.
A carefully graded soil allows the water to drain to the bottom of the pot, where it builds up a little before escaping from the drainage holes. The difference (in weight) between added and drained water amounts to the water retained in the soil.
It is worth taking the time to measure the two soil properties needed for healthy plants:
- Field Capacity – the water content remaining after saturation and drainage
- Saturation Porosity – the air content remaining in the soil after saturation and drainage
Measuring Field Capacity and Saturation Porosity in Potting Soil
Your Monstera (and other aroids) potting soil must balance water and air availability. To measure these interplaying factors, test the soil mix before planting, using a container of known volume and manageable draining holes.
- The soil mix density or specific gravity (weight by volume). Water is the standard with a density of 1 (ice is 0.9, and therefore floats on water as it’s less dense). The density of your soil mix is its dry weight divided by its volume.
- The Saturation Porosity (SP) is the difference between the fully saturated mix and the drained mix as a factor of its volume. Let’s assume the following:
- The volume of our container is 5 liters (5kg of water)
- The weight of the saturated mix is 5.2kg
- The weight of the drained mix is 4.5kg
- The SP (the fractional air content) is (5.2-4.5)/5 = 0.14 or 14%. Typical farming soil ranges between 2 to 7%. An SP below 6% indicates anaerobic conditions where roots cannot breathe.
- The Field Capacity (FC) is the difference between the drained wet weight and the dry weight of the mix divided by the volume. Let’s assume the following:
- The weight of the dry soil mix in the container was 1.5kg
- The weight of the drained mix is 4.5kg
- The FC (fractional water content) is (4.5-1.5)/5 = 0.6 or 60%. Typical farm soil is in the region of 50%.
Inexpensive yet effective components with good drainage and water absorption include perlite, calcine clay, bark, pea gravel, and granite grit.
|Material||Saturated Porosity (SP) – Air||Field Capacity (FC) – Water|
|Calcine Clay (Turface or Haydite)||28%||40 – 60%|
Irrespective of your soil’s ability to trap air even when flooded (saturation porosity), if the water addition and drainage cycles are compromised, that porosity is lost. Saturation porosity depends on thorough watering followed by total draining.
Following a watering and draining cycle, some water remains (field capacity), and the excess is drained. Air, too remains available to the plant roots, even at the saturation point (saturation porosity).
If water is continuously added without allowing a drying period between the saturation points, porosity becomes compromised, i.e., the air holding capacity of the soil is lost.
Yellowing leaves and rotting roots are signs of overwatering.
Overwatering is the main reason why potted plants die. When surrounded by water, roots cannot absorb oxygen – remember, they require water and oxygen just like humans do.
The general rule is to only water when necessary. To decide when to water, one may utilize the following techniques:
- Touch the soil: The most accurate test for soil moisture is to feel how dry the potting soil feels. If the mixture is dry at your fingertip after inserting your finger up to the second digit, it needs water. Check at least to a depth of a third of the pot.
- Tap the pot: When potting mix in a clay pot starts to dry up, it shrinks away from the pot’s sides. Use a stick or your knuckles to tap the pot’s side. Water is required if the sound is hollow; if the sound is dull, the soil is moist.
- Estimate weight: It’s easy to see a weight reduction as potting mixtures dry up.
- Assess soil color: As potting combinations dry, their color will shift from dark to lighter.
When watering is necessary, water deeply. Apply water until the bottom of the pot is completely submerged. Thorough watering removes accumulated salts and ensures that most of the roots in the bottom two-thirds of the pot get enough water. Empty the tray, and don’t let the pot sit in the accumulated water.
When soil particles are compressed, the pore space between them decreases, resulting in soil compaction. Few big pores, a lower total pore volume, and a higher density can all be seen in heavily compacted soils.
Because smaller pores are less able to drain water, compacted soil has a lower water infiltration and drainage rate.
Compacted soils also have a slower rate of gas exchange, which increases the chance of aeration-related issues.
The ability of soil to resist being moved by an applied force is increased by soil compaction, so roots must apply more force to penetrate the compacted layer.
The soil is less able to absorb water and air, causing your Monstera leaves to yellow.
Your soil is your most important resource when growing healthy plants. Preventing soil compaction will:
- Increase water infiltration and storage capacity
- Increase timeliness of field operations
- Decrease the stress on plant roots
- Decrease diseases potential
Gardeners will do well to repot their houseplants when they notice soil compaction.
Pythium and Phytophthora species are called “water molds” because they have a floating spore stage intended to spread within the water. They are the oomycetes responsible for root rot.
These organisms impact various plant species, causing root rot and stem rot. Instead of completely killing a plant, these pests typically induce partial root system loss, which leads to stunting, yellowing, and poor growth.
Overwatering and inadequate drainage are frequently linked to root rot. Drainage and aeration are compromised as potting media ages, settles, and becomes compacted in the bottom of containers.
Proper soil drainage, aeration, and watering frequency are necessary to prevent root rot. High salt levels are occasionally linked to root rot; thus, good water quality and regular soil leaching from containers are necessary to prevent issues.
2. Nutritional Imbalance – Causes of Yellow Monstera Leaves
We all know that nitrogen is a folial booster of note, but often too much nitrogen causes a build-up of salts that can cause Monstera leaves to yellow.
Remedy Soil Salts in Indoor Pots
Before you repot your Monstera, consider flushing the soil. Do this by running water through the soil to wash the salts out. Ensure you drain all the water from the pot before flushing it again. Repeat the process three to four times to ensure all (or most) the salts are leached out.
Using Epsom Salts
It could signify magnesium deficiency if your Monstera has V-shaped yellow areas on its leaves, especially in cooler conditions.
Epsom salt (magnesium sulfate) lowers the pH and provides magnesium and sulfur, two nutrients often deficient in alkaline soils. Benefits of magnesium for your Monstera plants include:
- Aids photosynthesis by helping your Monstera create chlorophyll
- Promotes healthy cell division and protein formation
- Increases Monstera’s ability to retain water
- Allows the Monstera to take in and use phosphorus
Magnesium has a poor cation exchange capacity (CEC), i.e., it binds poorly to soil particles. The only way your plant gets access to it is if it remains in situ near the roots, so repeat the process twice a year.
3. Monstera Environmental Stressors – Cause of Yellow Leaves
Change in Light Environment
A word of warning for Monstera growers trying plant relocation to solve yellow leaves; yellowing leaves can actually be caused by environmental changes. It would help if you allowed the plant to acclimatize to its new location.
Gardeners generally expect plants to grow towards light sources, but Monstera does the opposite – the phenomenon is called Skototropism. Monstera plants, instead of growing towards the light, grow towards the darkest point on the horizon.
Negative phototropism or skototropism helps Monsteras, as epiphytes, find a tree to climb. Remember this next time you rotate your Monstera in an effort to balance development – you’re contradicting the plant’s natural inclination.
Changes in Growing Environment
Monsteras frequently show sensitivity after a transplant. Stress can result from the roots being exposed for an extended time, a change in soil, or even repotting at the wrong time of year (late winter to early spring is best).
The leaves and petioles of a Monstera experiencing transplant shock will droop, making it appear to need watering. The oldest leaves will be the first to yellow.
The Monstera attempts to conserve nutrients and water by turning its leaves yellow after the stressful occurrence. It will ultimately return to normal and be even happier in its new pot. This may also aid in causing the leaves to split. read more about when does monstera leaves split
4. The Relationship between Light and Fertilizer
Gardeners familiar with plants’ micro development, especially photoperiodism, fruit development, and nutrition timing, will appreciate the relationship between these factors.
Photoperiodism is the response of an organism to seasonal changes in day length. Some plants need a definite amount of darkness for flowers to form.
At this point, the proportions of nutrients are very specific – a lower nitrogen level and boosted phosphorus (responsible for fat, carbohydrates, protein metabolism, and cell formation) and potassium (responsible for enzyme activity and water regulation).
Magnesium is the other essential element responsible for metabolism, fat formation, and chlorophyll production.
When a Monstera doesn’t get enough light, its growth slows down, so it doesn’t need as much water or fertilizer. It is much easier to overwater your Monstera in these conditions, which will cause the leaves to turn yellow.
Other symptoms of light deficiency include the following:
- Etoliation—extended stem reaching for the light, looks leggy or spindly
- Smaller leaves with less fenestration (holes and splits) or none at all
- Slow growth
- Soil takes a long time to dry out in between waterings
If your Monstera exhibits these symptoms and has started to develop yellow leaves, you need to check its roots for rot by removing them from the pot.
Avoid direct light on Monstera leaves. Reduce fertilizer levels to reduce leaf size, but do not lower levels so much that it reduces leaf color.
Add a teaspoon of Epsom salt to a gallon of water and flush the soil with the solution.
5. Monstera Pest Infestations
The major arthropod pests of this plant species include aphids, moths (worms), fungus gnats, mealybugs, mites, scales, and thrips.
Aphids are best removed by spray. Remember that Neem oil can affect soil microorganism that help boost plant resilience.
Again, remove any worms before they pupate.
Wherever possible, lessen the amount of water applied to each pot. Wherever possible, avoid algae growth. The larvae can be controlled by spraying the soil surface or soaking it in water.
Commercially available nematodes that hunt for insects in the soil have been found to manage these pests without harming the host plants.
Check out my article for guidance on getting rid of this pest.
Plants infested by scale become weakened or stunted and begin to die. The recourse is the same as for mealybugs – this article can help
Reduce the amount of water applied to each pot where possible. Avoid algae growth as chemicals are not believed to be very effective in controlling this pest.
Good sanitation with removing extraneous plant material and debris that might shelter these pests helps control them.
Many materials are registered and effective at controlling thrips.
6. Bacterial and Fungal Infections in Monstera
There are only three types of organisms that may cause chlorosis – yellowing of leaves:
- Pythium and Phytophthora species are oomycetes responsible for root rot. Their presence is always accompanied by an anaerobic environment caused by overwatering.
- Burrowing nematode (Radopholus similis) causes symptoms similar to the above oomycetes. The solution to the root rot they cause is also repotting.
- Dasheen mosaic virus (DMV) causes chlorotic streaking and mosaic patterns and distortion of new leaves. Dispose of your infected Monsteras.
7. Soil pH and Iron Availability
The most common nutrient problem of chlorosis is lack of iron, but yellowing may also be caused by manganese, zinc, or nitrogen deficiencies.
Iron becomes more insoluble and less available to plants as soil pH goes above 6.5 to 6.0. Monstera plants need a pH of between 6.0 and 8.0.
High amounts of other elements such as calcium, zinc, manganese, phosphorus, or copper in the soil can make iron unavailable to the plant. A shortage of potassium in the plant will also reduce iron availability.
Insufficient iron in the soil may also be the cause. Based on a soil test, the pH can be lowered by adding sulfur or applying the appropriate nutrients.
Foliar applications of water-soluble or chelated nutrients can temporarily correct the problem. However, it only helps the leaves present during application. Several treatments per growing season may be necessary to keep the foliage green.
8. High Temperatures and Drought
Potting media utilized for all Monstra species should have high water holding capacity and aeration. Amendments should include micronutrients and dolomite to supply calcium and magnesium.
Good plant growth will be obtained when soil temperatures are at least 65°F and air temperatures 70°F or above. Air temperatures as high as 105°F are not damaging to Monstera as long as soil moisture is adequate and proper light levels provided.
9. Natural Causes for Monstera Yellow Leaves
One of the causes of Monstera Adansonii’s leaves turning yellow is age. As your Swiss Cheese plant grows, its new leaves get bigger. To optimize resources, the Monstera redirects nutrients to the most productive parts, cutting off supplies to older leaves.
So the plant will redirect any nutrients to younger, more productive leaves from that old leaf before letting it fall off.
If your Monstera only has one yellow leaf down at the bottom and the rest of the plant is healthy and growing strong, you have no cause for concern.
Can yellowed leaves recover?
When a leaf becomes yellow, it won’t turn back green as the plant redirects nutrients to more vibrant foliage or grows new leaves.
Should I Remove Yellow Leaves off Monstera?
The yellowing of the leaves could be due to a disease like a fungus, wherein the damaged sections need to be removed and thrown away immediately.
However, you should wait until the leaf is completely dead if the yellowing is due to root rot or transplant shock. When the leaf dies, your Monstera will receive vital nutrients, so removing it too soon might increase the stress.
Love Monstera? So Do I; check Out Other Articles I wrote On Them?
Summary to Yellowing Monstera Leaves
There are several reasons for leaves to turn yellow in your Monstera (or Philodendron) plants. Before relocating the plant, check the root health first, as this is the most common cause of chlorosis of leaves.
If the root system is healthy, then systematically eliminate possible causes, but remember that sudden environmental changes can be a cause for yellowing Monstera leaves.
If you want to keep current on gardening, please email me your email address below, and I’ll send you the newsletter with all the new articles and special offers.