Calathea plants are a fantastic variety comprised of over 200 species, each with its own beautifully unique foliage. Their lush green colors and distinctive patterns add drama and interest to any space, making them a popular choice amongst hobbyists. The thing is, Calatheas are sensitive and tricky to care for at times.
If your Calathea is unhappy for any reason, they’ll show you through their leaves – and quick, so you need to pay attention! A partially yellowed leaf has a chance to be saved, but if you find a completely yellow leaf it’s likely as good as dead.
Your plant doesn’t need to suffer the same fate though, don’t worry – this just means something is off with your Calathea plant and you need to locate and remedy the source of the problem.
Causes For Calathea Leaves Turning Yellow
The truth is there are several reasons your Calathea may experience yellowing leaves. Unfortunately, more times than not, the plant is distressed – though this is not always the case.
It’s important to take immediate action when you notice discoloration on your plant. Calathea’s can deteriorate quickly when unhappy, so the sooner you solve the problem, the better.
Cause #1: The Circle of Life
If your plant has a yellowing leaf but seems healthy otherwise, it may just be the natural cycle of life taking its course. The leaves located closer to the soil will get old and eventually dry out, which is nothing to worry about.
How to Fix: Be sure to trim any dead or dying leaves with a sharp, sanitized pair of clippers. Removing dead leaves allows your Calathea to focus its energy on growing more robust, instead of putting the energy into a leaf that can’t be saved.
Cause #2: A Change in Environment
As we mentioned before, Calathea’s are very sensitive plants. Moving to a new environment can be enough to stress them out. Don’t be surprised by some yellowing when you first bring your Calathea home, as this is likely the reason. The more drastic the change to the environment, whether it’s the temperature or the amount of light, the higher the risk of shock to your plant.
Repotting your Calathea can also cause yellowing of the leaves as it adjusts and settles. If you’re planning to upgrade your plant to a bigger pot you can use Superthrive to help with the transition.
How to Fix: Superthrive is a concentrated vitamin hormone that stimulates plant growth and can be used to help reduce the stress associated with transplantation or damage. Give your Calathea time to adjust to their new conditions before panicking. If it’s been a few weeks and the yellowing has not improved, then it’s time to consider other factors.
Cause #3: Too Much or Too Little Water
Overwatering or underwatering – which is it? Either way, your Calathea will not be impressed. Watering Calathea plants can be tricky because there’s a fine line – they prefer soil to be damp, but not soaked. This makes overwatering a common issue for hobbyists who favor this variety.
How to Fix Overwatering: Check your plant a few days after watering to determine if it’s being overwatered. If the soil is still soaked after a few days, this is likely the problem. You’ll need to let the soil dry out, or possibly repot with new soil if you suspect root rot has set in. Be sure to use a soil medium with proper drainage to avoid oversaturating the roots of your Calathea.
How to Fix Underwatering: A thirsty Calathea will produce yellow leaves as well. If you find your plants’ soil dries out quickly you may want to use a heavier, more absorbent soil mix.
Calathea varieties need damp soil with good drainage to maintain proper hydration and strong healthy green leaves. Check your plants’ soil regularly to avoid over or underwatering, and only water your Calathea once the top layer of soil begins to dry out.
Cause #4: The Type of Water
You read that right – the type of water you use can turn your Calathea leaves yellow. Tap water contains plenty of impurities, including minerals, salt, and chlorine which can build up in the soil over time.
How to Fix: To avoid yellowing and possible chlorine toxicity, water your Calathea with filtered or distilled water – you can even use rainwater! Only certain varieties are sensitive to chlorine toxicity, but if you suspect it you can dilute the soil thoroughly with fresh, clean water.
Causes #5: You Have a Pest Problem
It’s possible a pest infestation may be causing your Calathea’s leaves to turn yellow. Although scale, aphids, and gnats are all attracted to tropical plants, spider mites are by far the most common pest a Calathea will encounter.
Look underneath your plant’s leaves for small white dots and a web coating – these are definite signs of a spider mite infestation.
How to Fix: You can treat your plant with horticultural and insecticidal soaps to get infestations under control, however brisk showers will help prevent future issues. Plan showers around your plants’ watering schedule to prevent overwatering and be sure to use enough force to knock those pests right off your plant!
Spider mites prefer dry conditions, so if you suspect an infestation, you may also want to increase the humidity of your space.
Cause #6: Overfertilization
Since Calatheas are such sensitive plants, it can be easy to overfertilize them. Most indoor plants don’t require heavy feeding, and the same is true for the Calathea. Fertilizers will increase the pH levels of your plants’ soil, which over time can accumulate and cause yellowing of the leaves among other issues.
How to Fix: Feed your plant 1-2 a month during the warmer months of the year, slow down during the autumn and stop fertilization during winter. Also, remember to flush the soil with clean distilled water every few months to dilute any potential buildup.
Cause #7: Humidity is Too Low
While many tropical plants do well indoors, humidity needs can often be a challenge to satisfy. You won’t be able to replicate the natural habitat of the Calathea, whose humidity levels sit around 90% – but levels must be above 50%.
How to Fix: To avoid yellowing leaves, browning edges, or other issues with your plant, use a humidifier or humidity tray to help maintain levels between 50-70%.
Cause #8 – Not Enough Light
Ensuring your Calathea receives enough light can be as tricky as watering it. You’ll likely notice yellowing leaves if your plant is placed too far away from sunlight, or in an area where it is not receiving enough light.
Most Calathea varieties need plenty of bright, indirect sunlight to grow strong – however, be mindful of how close you place it to the source. Too much direct light will scorch the leaves and cause soil to dry quicker, leaving your plant thirsty.
How to Fix: Use a light meter to measure how much light your plant is really receiving. My calathea care guides always note minimum and optimal light readings in footcandles (FC). Browse the website for your specific calathea variety for the most accurate info.
Cause #9 – Fungal Infection
Although it’s less common, a fungal infection or disease may be what’s causing your Calathea leaves to turn yellow. Fusarium is a soil-borne fungus that causes yellowing and wilting, and while your plant will not be happy, it is treatable.
How to Fix: Remove the plant from its pot and dispose of the soil. Gently rinse the soil from your plants’ roots and sterilize the pot before repotting with fresh soil. Hot humid conditions and poor airflow will encourage fungal growth, so be sure to use well-draining soil and avoid overwatering your plant.
Q: Yellow leaves with brown edges? What’s happening?
A: If you notice brown tips and edges or your Calathea, and it’s thriving otherwise, it’s very likely a humidity issue. If you don’t have a humidifier, you can increase humidity by grouping your plants closer together, or by keeping trays filled with water nearby.
Purchase a hygrometer from your local garden center or pet store to help accurately gauge the humidity levels of your home.
Q: Yellow leaves that are curling? What does this mean?
A: Curling and yellowing leaves are a sign that your plant is thirsty. Check to see if the soil is dry and be sure to keep checking it daily.
If you find the top layer of soil dries out quickly between waterings, you may need to change up the soil medium for something denser. Choose a soil mix that is both well-draining and absorbent for your Calathea.
Q: Why are yellow leaves only appearing during the winter?
A: If your plant’s leaves are only turning yellow during the winter season it’s likely caused by shorter days and colder temperatures. Try to keep your plants closer to an east-facing window that receives more hours of sunlight throughout the day.
Be careful though, because Calathea can be sensitive to drafts as well. If the cool winter breeze sneaks in, there’s a chance the dip in temperature may turn the leaves yellow too.
Q: What does it mean if a new Calathea leaf comes in yellow?
A: If your Calathea is regularly producing new growth, it’s likely thriving just fine. New leaves can sometimes grow in as a pale yellow-green and will develop to a deeper green as the leaf matures. Check all your bases to be sure, as there is always the risk of overwatering and potential root rot.
Q: Can a Calathea leaf turn green again after it’s turned yellow?
Unfortunately, you can’t fix a leaf that has completely turned yellow. In fact, if it’s that far gone, you’re better off removing the damaged leaf and allowing the plant to use its energy for new growth.
On the other hand, if the leaf has only begun to turn yellow there may be hope in saving it. If stress or poor nutrition has caused the discoloration, resolving the issue may help restore your plant to its beautiful deep green hue.