Aglaonema or Chinese Evergreen Yellow Leaves Reasons

Aglaonema or Chinese Evergreen yellow leaves is a likely sign of overwatering, underwatering and low humidity. But too much or too little light, extreme temperatures, nutritional deficiency, pests, diseases, and aging are other possible causes, with some causing yellow spots.

By considering any other sign present like brown tips and edges or splotches, leaves curling, falling, or the plant drooping, etc., you can deduce the most likely cause. Also, look at the soil moisture, temperature, light, and humidity.

We’ve all the reasons for Aglaonema yellow leaves. What you will learn applies to the various varieties like Aglaonema Silver Queen or Silver Bay, Red Emerald or Red valentine, Maria, or pink ones like Ultra Pink, Siam and Dalmatian or Watermelon. So, don’t go around looking for reasons specific to your variety or species.

Why leaves yellow

Plant leaves will turn yellow if they cannot make or something degrades chlorophyll. Factors that influence chlorophyll formation or degradation include the following

• Light
• Temperature
• Nutrients
• Water 
• Aging
• Parasites
• Disease
• Herbicides
• Water quality

All the causes we will be looking at have to do with Chinese evergreen care and anything that may upset the above factors.

Cause of Chinese evergreen yellow leaves

Now it’s time to start looking at the possible causes, starting with the most likely to those less likely. You can use the elimination method to help you pinpoint the reason for your unique case is.

1. Water or moisture issues

Overwatering is the most common cause of Chinese evergreen bottom leaves turning yellow. It cuts oxygen from the potting mix affecting suffocating the roots. Also, if not dealt with in time, it may cause Aglaonema root rot.

Without oxygen, roots are unable to absorb nutrients and water as usual. So, leaves will start turning yellow. Also, you may notice brown splotches, drooping, stunted growth, leaves falling off, and a constantly wet potting mix.

On the other hand, underwatering will make these plants unable to absorb nutrients. Also, water acts as a medium for many physiological processes, and absence promotes faster chlorophyll degradation. Signs include leaf scorch (dry, crispy tips and edges), drooping, leaves curling inward, and dry soil.

Water your Chinese evergreen when the potting mix’s top 2-3 inches feel dry. It may be after a few days to a week in growing months and after 2-3 weeks in fall and winter. But the exact duration depends on your conditions (temperature, humidity, or light), potting mix, pot size, or type, among other factors.

To know when to water, insert your finger into the potting mix. If it is dry up to the first knuckle, water your plant. Otherwise, wait for a few more days and test it again.

Another more convenient way is using a soil moisture meter. We use XLUX Soil Moisture Meter and water when the reading is three or less. This brand is accurate, responds fast and doesn't require batteries.

If you neglect your plants, consider a self-watering pot or set reminders after getting the approximate duration of the next watering session. However, you still need to test the soil.

Last but not least, your potting mix may contribute to watering issues. Ensure it is well-draining but still holds moisture. Perlite or bark chips will improve drainage, and coco coir or peat moss will help it retain moisture.  

2. Low humidity

If your Chinese evergreen grows in an area with low humidity, it may be the reason for the yellowing of leaves and leaf scorch (brown tips and edges), curling, drooping, etc.

Remember, this plant loves humidity, with the ideal being average to above-average 50% or more but can tolerate slightly lower levels. Too low will affect its growth and make leaves dull.

Mist your plants, have a pebble tray, or group your plants to help improve humidity. Also, you can move them to more humid rooms like toilet and kitchen if it has enough light.

However, if your humidity is too low, buy a humidifier. Any cool mist brand is ok. What you will pick will depend on your room size. AquaOasis™ Cool Mist Humidifier is good for small to medium rooms.

3. Too much or too little light

Chlorophyll synthesis in all flowering plants, including your Aglaonema, has a light-dependent stage, but too much can also cause damage

So too little light will cause a new growth with smaller leaves that may look paler or yellowish. Also, your plant will grow slowly.

On the other hand, too much light will make leaves look bleached, washed-out, paler, or yellowish. An obvious sign you will also notice is brown tips and edges.

To solve this problem, grow your Chinese evergreen plants under bright, indirect light for about 12 hours a day, avoiding direct sun indoors or outdoors. Indoors, place your plant at a distance from the window where direct sun except a bit of morning light doesn’t hit it.

If your apartment doesn’t get enough light, buy grow lights. Ideal ones should produce 10000 to 20000 lux (1000 to 2000 foot candles) of light. Your plant will grow well in such light. I use Relassy 15000Lux Sunlike Full Spectrum Grow Lamp. It has a long lifespan (50,000 hours) and a gooseneck stand.

4. Extreme temperatures

Low temperature will slow chlorophyll synthesis, and extreme coldness and cold drafts may damage cells if water freezes in the plant. Both these two will contribute to leaf discoloration, mainly browning. But it may also turn yellow.

On the other hand, extreme temperatures or heat stress will cause yellowing, i.e., it will degrade chlorophyll and disrupt synthesis. But common signs are brown tips and edges or leaf scorch.

Lastly, avoid cold drafts during winters and hot summer weather. Also, don’t place your plants near heat emitting or air conditioning vents or appliances emitting heat. Outdoors, move plants to a cooler place with a shade.

Nutrient deficiency

A deficiency of some of the various minerals may result in Chinese evergreen chlorosis. These nutrients may be part of chlorophyll like magnesium nitrogen or have a role in synthesis.

For instance, a deficiency in iron and manganese will cause interveinal yellowing, starting with younger leaves.

On the other hand nitrogen, zinc, and magnesium will cause affect lower leaves first. Others that will cause the yellowing to are cupper, sulfur, molybdenum, etc.

To avoid chlorosis due to nutritional deficiency, always feed your plants with premium quality, balanced fertilizer for houseplants. Do this monthly only in the growing months.

Jacks Classic 20-20-20 All Purpose Fertilizer is one the best brands to consider. Besides being balanced, it also has boron, zinc, manganese, molybdenum, copper and iron. Add ¼ a teaspoon to a gallon of water and use the solution to feed your plants biweekly. 

That is not all. Also, ensure the potting mix is rich in organic matter and has a favorable slightly acidic pH of 5.6-6.5 as it affects the availability of some nutrients.

6. Pests

Sap sucking pests like scale insects, spider mites, mealybugs, or aphids cause yellow leaves on Aglaonema, predominantly yellow spots. But heavy infestation may cause stunted growth, leaf falling, distortion, or even yellowing.

To help you see these bugs, examine the leaves, mainly the underside, with a 10X magnifying glass. Otherwise, to the naked eye, they may appear as tiny bumps or dots that may move or not. Some have a waxy body, others wings.

If you notice any of these bugs and their symptoms, use insecticidal soap, horticultural oil sprays, or neem oil to get rid of them. Also, hosing the plant may help dislodge these bugs.

Instead of buying all these products, we recommend Bonide (BND212) - All Seasons Horticultural and Dormant Spray Oil, Insecticide. It will kill all the pests (aphids, scale insects, mealybugs, mites, etc.) and help control diseases like rust, powdery mildew, botrytis, greasy spots, etc. 

7. Diseases including aglaonema root rot

Fungal and bacterial leaf spots, rusts, or blights diseases can cause Aglaonema yellow leaves. The common one is Dickeya chrysanthemi which will also cause leaf wilting. But anthracnose, Erwinia chrysanthemi, Xanthomonas campestris Dieffenbachiae, etc., may also cause yellowing, including brown lesions with a yellow halo.

Also, root rot may cause wilting and yellowing of leaves, stunted growth, mushy stems, and other symptoms.

Bacterial diseases have no cure. But bactericides with copper compounds may help prevent spread. If your plant has a fungal infection, use fungicides, and if root rot, repot it, removing the damaged parts with sterilized pruning scissors.

To manage diseases, practice proper sanitation (sterilize gardening tools, wash your hands, etc.), don’t place your plants on the ground or overwater your plants. Also, isolate and cut diseased leaves or parts. For severe cases, discard the whole plant.

8. Aging

Aging, or what is known as plant senescence, is an expected reason for yellowing that will affect only a few lower older leaves at a time. There is nothing much you can do. Remove affected leaves as they still depend on the plant, yet they don’t contribute. Also, they may attract pests.

9. Water quality

Water quality is rare and unlikely for Chinese evergreen leaves turning yellow. If high in chlorine, it will instead cause brown margin and tips. But if high in salts (affects nutrient absorption) or high in heavy metal (toxic to plants), it may cause chlorosis.

Switch to filtered or rainwater if you suspect water is responsible for chlorosis. Otherwise, you can let tap water stand in an open container overnight to help chlorine dissipate. It should prevent the brown tips and edges it causes.

10. Herbicides

Some of the owners of greenhouses that use herbicides may cause interveinal chlorosis if you misuse or misapply it. Commonly blamed herbicides are isoxazole, triketone, Pyrazolone, and Isoxazolidinone. We didn't least all of them.

Stop using herbicides or switch to those less known to cause the yellowing. Also, follow the manufacturers’ instructions.

Less common aglaonema yellow leaves causes

More reasons for Chinese evergreen yellow leaves include the following:

• Rootbound: Are roots growing from drainage holes or spiraling around the pot, and you see yellow leaves? Your Aglaonema is rootbound, and it cannot get enough nutrients or moisture. Repot your plant to a new pot, 2-3 inches wider in diameter.
• Repotting or transplant shock – Some leaf scorch, yellowing, falling off, curling, etc may occur if you just repotted your Chinese evergreen or relocated it. To reduce the effect, minimize root damage when repotting or transplanting. Also, provide optimum conditions and ensure the soil remains moist.

Chinese evergreen bottom leaves turning yellow

Chinese evergreen bottom leaves turning yellow is a sign of mainly overwatering. But it may be normal aging if it occurs to a few leaves, like 1 or 2 leaves at a time. Less likely reasons for lower leaves turning yellow include nitrogen, zinc, and magnesium deficiency.

should I cut yellow leaves off Chinese evergreen 

Yes, cut off yellow leaves on Chinese evergreen. But how you do it depends on the extent of the yellowing and cause. For instance, trim with a sterilized sharp scissor if only the margins are yellow.

On the other hand, most of the leaf has turned yellow or brown, or the cause is pests and diseases, you need to cut it with the petiole. Cut it closest to the stem with sterilized gardening shears.