Calathea houseplants have an active lifestyle to go with their dynamic patterns. Their leaves shift position dramatically over the course of each day and night, spreading out while it’s light out and folding upright when it gets dark. What causes this daily cycle? And should you be concerned if your plant’s motion slows or stops?
The movement of Calatheas (and related species like Prayer Plants) is driven by a fleshy joint at the base of the leaf that can fill with moisture or empty out to expand or contract. Scientists aren’t sure what benefit the plants get from this behavior, though they know that changes in light levels play an important role in signaling the leaves to rise and fall.
It’s not always cause for alarm when a Calathea stops folding its leaves up at night. The plant might just be getting a lot of artificial light late into the night, leaving it unsure if it’s time to raise its foliage. However, you should check for more significant problems like dehydration. In the right environment, a healthy Calathea’s foliage will rise and fall in a quiet, steady rhythm.
When Do Calathea Leaves Move?
A Calathea’s foliage constantly adjusts throughout the day, making slight movements up and down as the light around them shifts. But the most dramatic change, and the one for which they’re best known, happens when dusk settles in.
As the light dwindles and disappears, the leaves of a Calathea fold up and in, often taking on a nearly vertical position. The plant goes from a splayed-out, bushy appearance to something resembling a collection of delicate fans or feathers. In many species, this reveals rosy colors on the undersides of the leaves that are hidden during the day.
This rising and falling motion is called nyctinasty, though many houseplant owners call it praying since it looks almost like the plant is folding up its “hands” for bedtime prayers. This is also how the Calathea’s better-known cousin Maranta leuconeura got its nickname: the Prayer Plant.
Calatheas and Prayer Plants are in the Marantaceae family. Sometimes all the plants in this group get lumped together as “Prayer Plants” because they all exhibit the same nyctinastic behavior. For more on the differences between Calatheas and true Prayer Plants, you can read our article on the subject.
Exactly when your Calathea will tilt its leaves depends on the timing of sunrise and sunset (or of artificial lighting in the room where it lives). These plants typically begin lowering their leaves for the day around 20-30 minutes after the first rays of morning light hit them and start gradually folding back up as light starts to wane in the afternoon.
How Do Calathea Leaves Move?
Calatheas and other Marantaceae possess a specialized organ called a pulvinus. It’s basically a tube of thin-walled cells that can rapidly release or take up water, enabling them to swell and shrink dramatically. Pulvini are found at the base of a Calathea’s leaves, and they’re not always easy to spot. When a pulvinus is holding a lot of water, you may be able to identify it by looking for a slight thickening of the stem just below the leaf.
Nyctinasty is different from the way that many plants adjust their position to face the sun. That’s called phototropism, and it’s usually accomplished by differences in the growth rates of cells on opposite sides of the plant. The shadier side of the stem will grow faster, causing it to curve over in the direction of light.
A Calathea’s nyctinasty changes based on the intensity of illumination, but not the direction. The pulvini in the plant’s stems don’t do much to tilt it toward the sun. This is understandable, since Calatheas don’t actually do well in direct sunlight.
Why Do Calathea Leaves Move?
So if your Calathea’s leaves aren’t moving to snag some extra sun, why are they moving at all? This is actually still a subject of debate among botanists. Spreading the leaves out during the day obviously helps maximize the surface area that can absorb light, but it’s not obvious how folding back up at night helps a Calathea survive. Lots of theories have been proposed, but none have been convincingly proven.
Some of the most convincing hypotheses include:
- Temperature regulation. When the leaves fold in, the amount of exposed surface area drops, potentially allowing the plant to lose less heat during the cool hours of the night.
- Moisture control. The vertical or near-vertical tilt of the foliage might encourage raindrops and water vapor to drip down toward the roots, rather than beading on the surface of the leaves. In addition to helping this notoriously thirsty plant get a little more water, this could reduce the risk of fungal infections from pools of standing water on the leaves.
- Protection from insects. Leaf-munching bugs might have a harder time hiding from predators when the foliage is pointing straight up instead of splayed out in a bushy, concealing mat. By reducing the number of hiding places while nocturnal hunters are active, Calatheas may be helping out the enemies of their enemies.
For now, the true function of a Calathea’s nocturnal movement will have to remain a puzzle. It’s fun to think about, though, and you never know – if you can come up with a convincing explanation, you might just move botanical science forward.
What Does a Praying Calathea Look Like?
Some people hear the nickname “Prayer Plant” and picture the individual leaves folding up, or pairs of leaves pressing together like praying hands. That’s not what a Calathea’s nighttime movements look like. The leaves will rotate up to point toward the ceiling, but they won’t actually smush against each other.
Curling leaf edges are also not part of a healthy Calathea’s daily routine. When you see this happening, it’s a sign that the foliage is dehydrated. It could be due to sun exposure, high temperatures, low humidity, or underwatering, all of which we’ll address in more detail below.
Leaf curling can also result from an excess of minerals in the plant’s water or soil. Ease back on any fertilizer you’re giving your Calathea, and try using distilled water instead of tap water.
Why Isn’t My Calathea Moving? And What Can I Do About It?
After hearing so much about the fascinating movements of Calatheas, you might be concerned if you notice that yours isn’t showing the motion you expect. Under some conditions, these plants do slow or stop their usual cycle. If this is happening to your Calathea, don’t panic – it’s not always a sign of poor health!
If only one or two leaves have stopped moving, they may simply be aging out. A Calathea will devote less energy to a leaf that’s near the end of its lifespan. It’s also possible that the pulvinus has been damaged, preventing an otherwise healthy leaf from flexing.
When an entire Calathea stops or slows its movement, it’s time to assess the plant’s growing conditions. Take stock of its environment and consider whether one of the following factors is at work:
Too Much Light
Have you ever found that your sleep cycle is thrown off by staring at a brightly lit screen late into the night? Well, Calatheas have circadian rhythms too – and like yours, they can be messed up when it doesn’t get dark enough at night.
If you keep your plant in an office that’s illuminated 24 hours a day, or a room where light from a streetlamp is streaming in all night, it may not realize it’s nighttime at all. And even if your Calathea does get a few hours of total darkness, it may be hesitant to close up fully when it’s receiving bright light for more than eight hours per day.
There’s an easy fix: move your Calathea to a space that gets a more standard cycle of light and dark. Within a few days, it should be back to its usual pattern of movement.
Bear in mind that this kind of signaling issue doesn’t put the plant’s health at risk. Unlike humans, Calatheas don’t actually suffer from sleep deprivation, so yours will be okay even if you don’t move it out of the light.
Too Little Light
Since the contrast between day and night regulates a Calathea’s movements, the plant can get confused if it doesn’t receive enough light during the day. If this is your Calathea’s issue, you might also notice that the foliage has become paler, and the plant’s growth has become sluggish.
Though these plants are susceptible to sunburn, they do need a good amount of indirect light to thrive. Consider placing your Calathea in an east-facing window where it will receive a few hours of sun during the coolest part of the day. A south-facing room with sheer curtains over the windows to filter the light is another good spot.
Lack of Water
Remember that a Calathea’s praying motion is accomplished by shifting moisture in and out of the pulvini below its leaves. If the plant doesn’t have enough water to spare, it won’t be able to move. Other symptoms of dehydration include drooping, shriveled, or crispy leaves.
Check the soil in your Calathea’s pot if you think you might be underwatering it. You can poke a chopstick or some other long implement down to check the soil near the base; if it comes up totally dry, the soil isn’t moist enough for your plant. Those who like to get scientific might want to use a moisture meter instead.
If this test shows that the pot has dried out, you’ll need to step up your watering regimen. Try to ensure that the potting mix around your Calathea’s roots remains moderately damp, and you should see it praying again before long. This will be much better for its health in the long run. Calatheas are particularly vulnerable to dehydration, and letting the soil get totally dry between waterings can stress and even kill your plant over time.
Note that watering too much can be just as bad, if not worse. Damp soil is great for Calatheas, but soggy soil or standing water can suffocate and rot their roots. Your best bet is to check the pot regularly, watering only when the top inch or two of the mix has gotten dry.
Remember that watering issues are often really soil issues in disguise. It’s a lot harder to underwater or overwater a Calathea that’s planted in the right growing medium. You want a mix that has good drainage, but also includes a decent quantity of moisture-retentive elements like sphagnum moss or coconut coir. Potting soil intended for African Violets will usually work well.
Environmental Stress
Talk to someone who’s been growing Calatheas for a long time, and you’ll probably hear them describing the plant in terms that sound more appropriate for a spoiled toddler. These leafy beauties are known to dig in their heels and pout if they don’t have everything exactly their way. Any sudden changes in their environments can cause them to halt their normal routine.
This is particularly true when it comes to humidity or temperature. If you’re heading into winter and your Calathea’s praying motion slows or stops, it’s probably reacting to the increasing cold or the decreasing levels of water vapor in the air.
Try applying a little climate control. Move your plant into an area that remains fairly warm and humid – a bathroom is often a great choice, provided it receives enough light. Kitchens can also work well.
You can also apply some artificial humidity by misting your Calathea frequently with lukewarm water from a spray bottle. Or, of course, you could use a humidifier. This model has a warm mist setting that can also help keep the plant at the temperature it prefers, killing two birds with one stone.
Transplant Shock
If you’ve recently repotted your Calathea, it’s possible that it just needs some time to bounce back. Moving from one container to another puts a lot of strain on the root system. The plant may not have enough moisture and energy to spare for nyctinasty while it’s recovering.
In this case, the good news and the bad news are the same: there’s nothing to do but wait. Your Calathea needs to adjust to its new environment and re-establish healthy root growth. That should happen on its own as long as you’ve placed it in the right type of soil and you’re keeping it warm and watered. Be particularly attentive to the plant’s humidity needs during this delicate stage.
Spider Mites
These nasty little arachnids like to suck the sugary juices out of the stems below a plant’s leaves – in other words, right from the exact spot where your Calathea needs moisture to raise and lower its foliage.
Of course, if you have a spider mite infestation, a few missed prayers are the least of your plant’s worries! Mites can kill a Calathea if left untreated. If you think this may be what’s affecting your plant, you should quarantine it right away. Keep it in a room away from any other houseplants to keep the little critters from spreading.
Then inspect the plant’s leaves for signs of damage. Spider mite attacks usually appear as clusters of tiny pale spots on the leaves (especially the undersides). You might also see wispy webbing strung between the stems and leaves of the plant.
The mites themselves can be hard to see with the naked eye. Try holding a sheet of paper under the leaf and tapping on your plant. If lots of teensy specks that look like flecks of pepper fall onto the page, you’ve got a pest problem.
To get rid of spider mites, wash the foliage with a fairly intense jet of water from a hose or faucet. After it dries, spray it down with a weak solution of mild liquid soap – around one teaspoon of soap per liter of water, shaken well. Mist this over your entire Calathea, getting all the nooks and crannies. Wait about 10 minutes, then rinse it off.
You’re probably going to have to repeat this treatment several times to get rid of all the mites. It can also be helpful to add some neem oil, a powerful natural insecticide. Try a ratio of ⅓ of a teaspoon of liquid soap, 1 teaspoon of neem oil, and one liter of water. Again, shake well, and keep shaking every few minutes while you’re spraying.
For more information on Spider Mites and Calatheas, read this article.
Final Thoughts
A Calathea’s praying routine is fascinating to observe in action. Keep your plant healthy and happy, and you should be able to see this intriguing behavior for yourself. We hope this article has given you a better understanding of your tropical beauty and the care it needs.