Calatheas are known for their lush foliage with stunning and ornate patterns, so it can be disappointing and concerning if their leaves turn yellow.
The most likely reason your Calathea’s leaves turn yellow is underwatering or overwatering. Still, there could be other reasons that your Calathea may develop yellow leaves, from humidity issues, fungal infections, a pest problem or even shock.
If you notice some yellowing leaves on your Calathea, some investigating will quickly tell you how and why the leaves have turned yellow, so you can begin to fix the problem and help your Calathea thrive again.
If your Calathea has been underwatered, it will develop yellow leaves as a sign of stress. The leaves will turn yellow beginning at the exterior. The tips will turn brown and become crispy. This yellowing will eventually move inward as the leaf begins to die off.
If you have underwatered your Calathea, it will enter survival mode and will try to do everything it can to conserve water. Since Calatheas have fragile and delicate leaves, they lose water very quickly through transpiration and will lose leaves rapidly if they are dry for too long. As a result, your Calathea will allow a few leaves to die off to conserve its resources.
In addition to yellowing, your Calathea will curl its leaves, and they may become deflated. You will also find that the soil is dry.
How To Solve Underwatering
If your Calathea’s leaves are turning yellow due to underwatering, the first step would be to give it a thorough drink. If the soil is parched, you may want to water it once more after a few minutes, as dry soil will not absorb the water effectively the first time.
If your Calathea was so thirsty that it was also drooping and curling, you might still notice one or two leaves turning yellow even after watering it.
Calatheas notoriously need plenty of water. Unlike succulents or Snake Plants, they do not store water in their leaves, so they prefer to have moist soil. If you struggle with determining the moisture levels in your Calathea’s soil, purchasing a moisture meter will take the guesswork out of watering your Calathea.
If keeping up with your Calathea’s watering routine is challenging, you may consider using a self-watering pot. A ceramic pot with drainage is another excellent choice for Calatheas, as it tends to retain moisture much better than plastic or terracotta pots.
On the other hand, it is possible to overwater your Calathea, which can also cause its leaves to turn yellow. Calatheas enjoy living in moist soil. However, plants can be susceptible to root rot if they sit in soaking wet soil for too long.
You may notice that leaves have turned yellow and are a bit mushy closer to the stem. Your Calathea may also wilt or curl if the overwatering is severe.
How To Solve Overwatering
If overwatering is the issue, you will want to change the wet soil immediately.
Rinse the roots in lukewarm water and inspect them for root rot.
If there are dark and slimy roots, trim them away, along with any affected leaves or stems.
If there aren’t many healthy roots left, place your Calathea in water until more roots grow. You can also use cinnamon or a rooting hormone to stimulate healthy root growth.
If there isn’t root rot and there are a substantial amount of healthy roots, you can pot your Calathea in fresh soil. If you’re using high-quality soil that is naturally a little bit moist, you can safely wait 24-48 hours before watering your Calathea again.
Make sure to pot your Calathea in a soil mixture with proper drainage. While Calatheas prefer a moist environment, you want to ensure that the soil is not too compact that it deprives the roots of oxygen. Adding 10-25% perlite to your soil will go a long way in making your soil less dense for your Calathea.
More importantly, you will want your Calathea to have a pot with drainage.
Drainage holes in the base of the pot will allow the excess water to escape, along with any other toxins built up in the soil between waterings. Not only will this prevent overwatering and root rot, but it will reduce the likelihood of your Calathea developing a fungal or bacterial infection.
Pests are particularly drawn to Calatheas not only because their foliage is exceptionally soft and delicate but also because they quickly become stressed. Therefore, if your Calathea is unexpectedly yellowing, particularly newer leaves, and you notice that new growth is emerging with leaf damage, you likely have a pest outbreak on your plant.
While just about any houseplant pest can cause yellowing leaves in your Calathea, two pests love Calatheas: thrips and spider mites.
As pictured, if your Calathea has spider mites, you may also find webbing on the leaves or what appears to be dust on the undersides of the leaves.
Read more: How to Get Rid of Spider Mites on Calathea
Thrips can be much harder to spot on Calatheas, and they can be deadly.
If your Calathea has thrips, you may notice their fecal matter left behind on the undersides of the leaves, as well as tiny white “specks” on the leaves, which are thrip larvae.
Adult thrips are small torpedo-shaped insects that tend to hide under the leaves and can be more challenging to detect.
How to Treat and Prevent Pests
If you suspect that your Calathea has a pest problem causing the leaves to turn yellow, you will want to immediately isolate your plant from other plants to stop them from spreading.
- First, spray your Calathea with water to blast away any visible pests, and consider trimming any infested foliage.
- Trim any dead or dying foliage that will attract more pests in the future.
- Next, treat the rest of your Calathea with insecticidal soap or a neem oil solution, and place it in a warm, humid location.
You may need to repeat this process several times, especially when treating thrips.
Calatheas are native to warm, tropical environments. If the air is too dry in your space, you will notice yellowing start to appear on the outer edges and tips of the leaves.
Calatheas need a minimum of 50% humidity but prefer conditions in the 60-80% range. If you aren’t sure what the humidity levels around your Calathea might be, you can purchase a hygrometer.
How to Increase Humidity Levels For Your Calathea
Many hacks and tricks online, such as pebble trays or misting, can temporarily raise humidity levels for your Calathea. However, a humidifier is the most efficient and effective way to boost humidity.
If your bathroom has acceptable humidity levels and a window with gentle light, relocating your Calathea is also a great option. However, a humidifier is the best solution to raise humidity levels in your space if you live in a drier climate or have a furnace running in the winter.
5. Fungal Infection
Many people are unaware that Calatheas are highly susceptible to fungal infections, which will cause their leaves to develop yellow patches that eventually turn brown and crispy.
Unlike underwatering, a fungal infection will cause the leaf to turn yellow in seemingly random locations on the leaf. The yellowing will appear in patches or circular spots.
How to Solve Fungal Infections
To fix a fungal infection, you can purchase a fungicide from your local garden center or big box store. Follow the instructions carefully on the bottle.
You will not be able to repair the damaged leaves, but it will prevent the fungus from spreading and ensure that new growth is not affected.
Fungal infections can happen from water sitting too long on the leaf. It is a common problem for people who mist their Calatheas regularly with tap water.
Instead, swap your mister for a humidifier to prevent fungal infections, and only use distilled water. In addition, keep your Calathea in a location with airflow to keep conditions where fungus typically thrives to a minimum.
6. Natural Leaf Death
If your Calathea’s outer leaves shrink over time and eventually begin to yellow and drop off your plant with no reasonable explanation, it could be that it has come to the end of its natural life cycle.
Calatheas produce new growth at the center of the plant, pushing older growth further to the exterior. A lot of energy is required to grow their ornate foliage, so over time, those older leaves are allocated less energy, causing them to shrink and eventually die off.
If you notice that one or two small leaves on the exterior of your Calathea are turning yellow and the remainder of your Calathea is showing no visible signs of stress, you can prune the older leaf.
Removing the dying foliage will help your Calathea focus on new growth, and it will help prevent pests.
7. Chemical Burns
Calatheas are very sensitive to strong chemicals, which can cause their leaves to turn yellow and crispy.
Giving your Calathea chemically-treated tap water could be the culprit for turning your Calathea’s leaves yellow. Instead, water your Calathea with distilled or filtered water or rainwater if you can source it.
If you have been using tap water and notice some leaf yellowing on your Calathea, you can prune back the affected leaves and switch over to distilled water.
Calatheas can also develop yellow leaves from fertilizers, mainly if too much fertilizer is too strong.
Many garden centers will fertilize their Calatheas to encourage growth and give them a more bushy and full appearance, but once people take them home, they develop yellow leaves with black tips, almost as if they had been burnt.
Some people will also add fertilizer to their new Calatheas, unaware that they have already been fertilized, and this can also cause yellowing leaves.
How To Manage And Prevent Fertilizer Burn
When you bring your new Calathea home, it’s best to skip on the fertilizer until the following growing season.
Some Calatheas have slow-release fertilizers in their pots, which are tiny colored beads that sit on top of the soil and slowly dissolve with moisture over time. If there is an excessive amount of these beads on your soil, scoop them out to avoid overfertilizing your Calathea in the future.
When you give a Calathea fertilizer, they prefer a balanced fertilizer of 10-10-10. However, I’d recommend diluting that mixture even more than the label suggests to be safe. Calatheas prefer a gentler fertilizer like worm castings or a fish and seaweed blend fertilizer.
8. Too Much Light
If your Calathea is getting too much light, you will notice signs of stress quickly emerge, including yellow leaves and leaves that are curling or folding.
This is because Calatheas grow in the understory of tropical forests in the wild, where they occasionally receive dappled sunlight from above.
They have adapted well to receiving medium to low light levels, which is why they will fold their leaves upward in the evenings, giving them the nickname “Prayer Plants.” The purple undersides of their leaves will reflect the light fragments in a space so they can absorb as much light as possible, even if there is little to go around.
Calatheas are not used to receiving bright light, especially direct sunlight. As a result, your Calathea will curl its leaves to protect itself from the sun, and the leaves may turn yellow. You might also notice the intricate patterns on its leaves begin to fade.
What To Do if Your Calathea Has Been Getting Too Much Light?
If your Calathea receives too much light, you can pull it back further away from that light source.
Calatheas prefer low to medium light levels, around 200-400 Foot Candles.
Placing them 1-3 feet from an Eastern or Western facing window is best. Still, they can also manage quite well with some Northern exposure or significantly pulled back from a Southern-facing window.
Give your Calathea plenty of humidity and warmth while it recovers, as the excess light may have caused it to go into shock. In the meantime, trim away damaged leaves and monitor closely for pests until your Calathea has fully recovered.
9. Shock or Damage
If your Calathea has experienced any drastic environmental changes or undergone any physical damage, you may find a few leaves turn yellow and die off.
This type of yellowing will occur on the specifically affected leaves. Still, it can also happen to many exterior leaves as a means to conserve energy.
There are many different reasons why a Calathea can experience shock:
- Bringing a new Calathea home from the garden center or greenhouse where it was receiving optimal conditions.
- Temperature changes, particularly temperatures below 65ºF (18ºC).
- Your new Calathea was shipped to you from an online purchase.
- A child or a pet knocked over your Calathea.
- Your Calathea has been sitting next to an open window, a vent, or in a drafty location.
- Your Calathea recently had a pest problem.
How to Fix Shock
Unfortunately, the best that you can do for your Calathea when it is experiencing shock is to give it a warm, humid environment and give it time and patience until it recovers.
Make no further drastic changes to your Calathea’s conditions if you can help it, and monitor it for pests. Once your Calathea produces new, healthy growth, it will signal that it has recovered.
Can A Yellow Leaf Ever Turn Green?
Unfortunately, once your Calathea has sustained damage to the leaf, either by developing yellow spots on the leaf, crispy tips, or the leaf has turned completely yellow, it is permanent.
The yellow means that part of the leaf has died. While you cannot save the leaf, you can prevent other leaves on your Calathea from turning yellow.
Should I Remove Yellow Leaves From My Calathea?
If the leaf is more than 40% yellow, it is a good idea to prune back that particular leaf so your Calathea can focus its energy on producing healthy new growth.
In addition, removing the affected leaves will help reduce the spread if the issue is a pest or fungal problem.
Pruning yellow leaves will also help avoid a future pest problem if your Calathea shows signs of stress.
The only exception would be if pruning would not leave your Calathea with enough leaves for photosynthesis. Therefore, you will want to leave a couple of leaves on your Calathea until new growth emerges.