Monstera adansonii yellow leaves often indicate moisture or light issues. However, nutritional deficiencies, heat stress, cold drafts, pests, and disease, including root rot, may be to blame. Other possible reasons for the yellowing are aging (normal), transplant shock, repotting, or if your plant is rootbound.
To correctly diagnose the main cause of the yellowing, including yellow spots, you must look at other signs. You will often notice signs like wilting/drooping, stunted growth, leaves curling, falling off, or browning.
Also, there may be signs like brown splotches, tips, edges, or spots, black spots or splotches, mushy stem bases, very wet soil mix, soil pulled from the pot’s edges, etc.
Today, we will help you identify or pinpoint why your Monstera adansonii or swiss cheese plant leaves are turning yellow. We will also give you fixes once you detect the issue.
Monstera adansonii yellow leaves diagnosis steps and fixes
Leaves turn yellow when the plant cannot make enough chlorophyll (the green pigment) or something is damaging or degrading it.
Except for normal aging, these causes have something to do with improper care needs and wrong growing conditions. However, sometimes it may be pests or diseases.
The easiest way to pinpoint the cause is by eliminating the less probable reasons. Afterward, you will conduct a few easy tests until you find the reasons.
Step 1. Rule out transplanting shock and repotting stress
If you haven’t transplanted, moved, or repotted this plant, the yellowing isn’t due to any of these reasons. You can strike these reasons right away.
Step 2. Strike out aging
If yellowing occurs to one or two lowermost leaves, it may be normal aging. It occurs due to programmed cell death and chlorophyll degradation. If more leaves are yellowing, it is not normal aging.
Step 3. Look at and feel the potting mix with your finger
Moisture issues (overwatering, underwatering) are all possible and the most common reasons for yellowing.
You can easily determine if any of these is why your plant has leaves yellowing by looking at and feeling or testing the potting mix.
a). Are you overwatering this plant?
Overwatering is the most common reason for Monstera adansonii yellow leaves. The yellowing will start with lower leaves and occur without the leaves feeling dry or having brown tips or edges.
Feel if the soil is soggy even after not watering the plant for several days. Also, check for leaf edema, brown or black splotches, and sometimes mushy stem base, leaf defoliation, and a moldy potting mix. If you see some of these signs, it may be overwatering or root rot.
b). Is it underwatered or thirsty
Letting the soil completely dry or forgetting to water this plant at the right time may be why you notice the yellowing.
Confirm if the soil is bone dry and pulling from the pot’s edges (main sign) and that your plant is limp with leaves curling, drooping/wilting, or feeling dry. Other things include brown tips and edges of leaves, stunted growth, or leaves falling off the plant.
c). How to fix watering issues?
If moisture issues are the reason for your adansonii leaves turning yellow, then you need to ensure the following:
- If overwatering is the problem, don’t water your plant. Then improve ventilation and take it to a brighter spot if the light isn’t enough. Also, check if the soil drains, i.e., does it allow water to flow through? If not, amend it by adding perlite and bark chips.
- If the problem is underwatering, thoroughly water the plant until water flows from the drainage hole. Discard any that collects on the saucer. Also, check if the potting mix doesn’t hold water and add peat moss or coco coir.
- Afterward, only water when the soil feels dry up to the first knuckle. Alternatively, you can water it when your soil moisture meter reads dry. I use XLUX, and it is an excellent brand.
- Lastly, don’t alternate between bone-dry and wet soil. It will stress this plant and possibly make it have yellow leaves.
Step 4. Check the lighting situation
Is your plant in a dark or poorly lit room, or does it grow directly in sunlight? Both these two may result in the yellowing of leaves and are common reasons.
a). Too little light
Is your Monstera adansonii leggy, growing slowly and towards the light, and has smaller, paler, yellowish leaves? Too little light may be the issue since it will affect chlorophyll synthesis and food-making.
Little light may make some of the variegated Monstera adansonii plants may revert to green too. It happens to help make more food.
b). Too much sunlight
Does direct sun hit your plant? The yellowing, washed out, faded, or paler leaves are a possible result. Also, this may have yellow spots or patches and brown spots, tips, or edges, as it will degrade chlorophyll.
c). Fixing light issues
Place your Monstera adansonii at a spot with bright, indirect light at a distance from the window where direct sunlight cannot hit it. The early morning sun is ok. If outdoor, select a shaded place or one that receives dappled light. Also, you can consider a shade cloth.
For too little light, consider an illuminance meter like Dr.meter LX1330B Digital Illuminance Light Meter, if possible. A reading of 10000 to 20000 LUX is perfect.
And if your light isn’t enough, you buy grow lights. For a single small plant, I use GE Grow Light. If you have many plants, consider MARS HYDRO TS-1000 Led Grow Light. Also,
Step 5. See if the roots are mushy black, gray, or brown
If not moisture issues, root rot may be a possible cause of leaves yellowing, wilting/drooping, or having brown tips and margins. Also, it can cause a moldy potting mix, foul smell, mushy stem base/crown rot, stunted growth, defoliation, and sudden collapse.
Slide your plant out and check the roots. Root rot isn’t the reason if they are healthy (white or pale tan roots). However, if you see mushy black, brown, or gray roots, it is a possible reason for the yellowing, and you need to immediately repot the plant if it still has some healthy roots.
Step 6. Check out if it is rootbound
A rootbound plant will show signs similar to a thirsty or nutritionally deprived plant. Check if roots are growing from drainage holes or slide the plant out to see if they are spiraling in the pot.
If not, rule it out. If rootbound, repot it immediately to a pot 2-3 inches wider in diameter.
Step 7. Is it heat stress or cold drafts
Extremely high temperatures or being in a place with cold drafts will stress these plants, making their leaves yellow.
a). Heat stress
check if your plant is near room heating vents, heat emitting appliances, direct sunlight, or in warmer places. The excess heat will degrade chlorophyll and affect normal physiological processes.
Besides the yellowing of leaves, the affected plant may curl leaves, have dry edges or tips, and wilt. Also, your plants may need more water.
b). Cold drafts or cold shock
Cold drafts and cold shock will stress your Monstera plant resulting in leaves wilting or drooping, looking burnt, or turning yellow, whitish, or faded. Also, the plant may be mushy or black and have brown, black, or yellow spots.
c). How to deal with extreme temperatures
Monstera adansonii grows best at temperatures of between 55-80°F. Consider getting a thermometer to help monitor the temperature.
If heat stress is the issue, don’t place your plant near heat-emitting vents or appliances like a furnace, radiator, etc., and move any outdoor plants to a shaded area. Also, ensure they are thoroughly watered but don’t fertilize them until it recovers.
On the other hand, if cold drafts are the reason, you need to move any plants from open windows, doorways, or places with cold drafts. Also, ensure they are well watered, and move outdoor plants inside, to greenhouses or put them in cold frames.
Step 8. Does your plant lack some nutrients?
If you notice interveinal chlorosis or yellowing, you should suspect nutritional deficiencies.
Iron deficiency will affect the upper leaves first, while zinc, nitrogen, and magnesium lower ones first. Others that cause yellowing are sulfur, manganese, and molybdenum deficiency.
To fix this issue, ensure your potting soil has enough organic matter (worm castings or compost). Also, you can include some potting soil in the mix as it contains some of the micronutrients.
Feed your Monstera adansonii with a balanced, liquid fertilizer once a month during growing months only, starting with half recommended strength. However, unbalanced, including slow-release formulas, are ok so long as they are for potted or houseplants.
Step 9. Check for pests or bugs
Pests like mealybugs, whiteflies, spider mites, thrips, and scale insects can cause brown, black, or yellow spots.
Use a 10X magnifying glass to examine these bugs’ presence and check for any of their signs. Common signs include silvery stippling, curly or ruffled leaves, webbing, sooty mold, honeydew, etc.
Use insecticidal soaps, horticultural oil sprays, or neem oil to control these pests. All these methods are safe for indoor use.
Step 9. Check for brownish lesions with yellow halo – diseases
Does your plant have brownish lesions with a yellow halo? It may be a sign of fungal or bacterial leaf spot diseases. Some, like anthracnose, will result in yellow leaf margins.
Isolate new plants, prune affected parts with sterilized gardening shears and discard those severely affected. Also, practice proper sanitation, like washing hands with warm soapy water before and after handling plants.
Lastly, using copper fungicides may help manage diseases caused by bacteria and treat those caused by fungi.
Frequently asked questions
It is likely a sign of overwatering and rarely magnesium, zinc, or nitrogen deficiency. Some lower leaves yellowing may be normal aging if it affects a few leaves.
Yellow leaves with brown tips signify underwatering, heat stress, too much light, and repotting or transplant shock.
The main reasons for Monstera adansonii leaves turning yellow and brown is underwatering and too much light. However, overwatering, cold drafts, pests, and diseases may be a cause.