Curling leaves on your calathea plant are a sign of distress. Your calathea is signalling that something is off in its environment, and you need to figure out what to put your calathea plant at ease again.
Once the problem is identified and resolved, the leaves will unfurl. But what could be the cause of calathea leaves curling?
The problems that could be causing calathea leaves to curl are all related to changes or shortcomings in the keeping requirements of your plant.
Because there are quite a few things that may be stressing out your plant, I’m going to examine them one-by-one to help you identify the problem more easily.
You can think of this guide as a checklist that you can quickly run through should you even notice curled leaves on your calathea plant.
What’s Causing Calathea Leaves to Curl?
Here’s a quick overview of the things I’m going to cover as possible causes of distress for your calathea:
- Excess light
- Low humidity
- Bad temperature range
- Bad watering routine
- Water quality issues
As you can see, these are causes that you can change and influence, and get your calathea plant back into good shape.
Exposure to Direct Sunlight
Why is direct sun exposure causing curling leaves on your calathea? It has to do with the amount of light these plants have evolved to tolerate.
Growing beneath the canopy of tropical forests, these plants are accustomed to a shady, low light environment, therefore any excess light will put a strain on the plant.
As a response, calathea plant leaves curl in an attempt to reduce the surface area exposed to the sun. Indirect sun is fine for these plants and they’ll even benefit from it but avoid any amount of direct light.
Therefore, sunny windowsills are simply not a good option for these plants. If exposed to direct light, its leaves will not only curl, but they can get scorched easily.
If you’ve accidentally placed your calathea plant in a location with direct sunlight, getting it out from the sun in a shady location will help unfurl the leaves in a matter of a few days.
As for direct sun exposure, I would recommend generally avoiding it for most of your houseplants. Only a few plants will do well under direct sun exposure, and calathea plants are definitely not one of those plants.
If direct sun exposure is to be blamed for your calathea curling its leaves, usually, there are other symptoms too like scorching.
If you think direct sun exposure may be stressing out your calathea plant, make sure to move it somewhere out of direct sunlight. Give it a few days to see if the leaves unfurl. If the leaves stay curled and there’s no improvement after a couple of days, the problem may lay elsewhere.
Lack of Humidity
Calathea plants thrive in high humidity and they make use of their large leaves to absorb humidity. If the air is too dry, the leaves will curl up, turn yellow and brown around the edges, and they may even become brittle and rough if the air is extremely dry.
If you suspect that low humidity is causing your calathea plant’s leaves to curl, you’ll need to increase the humidity around the plant by gently misting its leaves.
This will offer the leaves an immediate boost of humidity, but it’s only a temporary solution that will not have long-lasting effects.
If misting won’t solve the problem of curling leaves, you may need to look for a more permanent solution like a humidifier.
Alternatively, you can use a tray of pebbles or peat moss submerged in shallow water to increase humidity and continue to mist your plant regularly.
When misting, make sure the water is clean to avoid any bacterial or fungal overgrowth.
Low humidity is a common reason why the leaves of calathea curl up, especially because the air in our homes is often too dry for these plants.
The temperature range accepted by calathea plants is between 60-85°F (16-29°C). If it gets too cold or too hot, calathea plants will respond by curling their leaves.
Even within this range, you may notice a slight curling if temperatures are towards either end of the spectrum. If this happens, adjust the temperature to see how the plant reacts.
Be mindful of cold drafts, heat vents, or air conditioning systems directly blasting hot or cold air onto your plant. Any of these circumstances can shock your calathea plant and cause curling leaves.
When positioning your calathea plant in your home, hold your hand out on all sides of the plant to see if you feel any cold drafts or other cold or warm source of air hitting the plant.
Find a place that is away from heat sources or cold drafts to prevent exposing your calathea plant to thermal shock.
Thermometers are a good way to monitor the air temperature around your calathea and see if there are any adjustments needed to ensure that your calathea is comfortable in its environment.
The temperature range that calathea plants can tolerate is easily recreated in our homes, but there can be sudden deviations that we might not think could affect calatheas, such as turning the AC on or opening a window during the winter, and exposing the plant to a cold draft.
Bad Watering Routine
When I say bad watering routine, I mean either watering in excess or underwatering. Both extremes can cause the leaves of your calathea to curl, but of the two, underwatering will more often lead to curling leaves. Still, overwatering is the more dangerous of the two.
Calathea plants enjoy moisture, but some will take this to mean that they should frequently water their calathea, and frequently may mean something different for different folks.
When watering these plants, a good thing to guide yourself after is the state of the potting medium. Calatheas prefer damp soil. Extremes like soggy soil will without doubt cause root rot, while soil that’s too dry will cause the leaves to curl.
The top of the soil can slightly dry out between waterings, but sticking your fingertip into the soil should still reveal some level of moisture beneath the surface.
Avoid having standing water at the base of the pot, make sure the water you use is room temperature, and check on the plant every other day to see if it needs watering.
During winter, you will need to reduce the frequency of watering, but continue to check the soil and let it guide you — along with the health status of the leaves — in correctly watering your calathea.
By developing a good eye for assessing the state of the potting medium, you’ll easily prevent extremes in your watering routine.
Water Quality Issues
I mentioned that you should use ambient temperature water to avoid shocking the plant. Likewise, you should also know that water that is rich in minerals, salts or hard water can also cause leaf problems including curling.
If you have information about the quality of your tap water — you can ask your water provider for a water report to check the different levels of minerals in your water and other substances — you will be able to tell if hard water may be causing these issues.
If you don’t have any information about the quality of your tap water, and you’ve ruled out all other possible causes I discussed in this article, you may use distilled or bottled water for a while to see if things change.
While distilled water or bottled water can be considered as good alternatives to tap water, I would recommend watering with rainwater if you can.
If leaves unfurl after switching from tap water to rainwater or other alternatives, it’s highly likely that the quality of your tap water was stressing your calathea plant.
I’d venture to say that low humidity is one of the most common causes of calathea leaves curling, but all of the above possible causes should also be examined and ruled out.
Whatever changes you make, monitor you calathea for a couple of days. Sometimes improvements will happen within a couple of hours (e.g. after misting if the air is dry, or watering if the soil is too dry), but sometimes it will take a couple of days to see changes in the state of your calathea, so you’ll need to be patient.
Calathea plants are sensitive to direct sun exposure, overwatering, low humidity, and other environmental factors that I discussed above.
Because curling leaves can be a symptom of all the things I discussed in this article, you’ll need to examine and rule out each possible case before you can zero in on the problem.
Except for root rot caused by overwatering, most of these issues can be easily remedied by making the necessary adjustments.
By understanding the exact needs of your calathea plant and working out an environment in which it can thrive, leaf curling can both be prevented and remedied.