I’m a big fan of two unusual activities: staying up late and watching my house plants—and I sometimes do both simultaneously. Night time is a fascinating time for nature—that’s when you see cool stuff like stars, the Milky Way, and calathea plants that seem to stand. And while it can be unnerving to see your plant perked up, there’s a good explanation for this behavior.
Your calathea plant perks up at night because of a process known as nyctinasty. The behavior is typical for calatheas and many other plants, and it’s the plants’ natural reaction to external stimuli. Nyctinasty is usually triggered by low light but can also happen because of low temperatures.
You need to learn the natural behaviors of your calathea plant—whether you’re keeping it indoors or outdoors—so you can correctly care for it. In this article, I’ll explain how nyctinasty works in calathea plants, the reasons for the response, why it might be having issues perking up, and vital questions relating to calathea care and growth. Let’s get started.
Definition and Significance of Nyctinasty
Plants—like animals, people, and insects—are alive and capable of interacting with the world like every other living thing. However, most plants are typically slower when reacting to the outside world. It usually takes unfavorable conditions, disease, or death for you to see dramatic responses from them.
Still, several plant species exist today that can react to changes in stimuli in real time—similar to what you’d see in other living species. And although the responses might not be as fast as you’d see in animals, they’re vital to the development and survival of these plants.
You’re probably familiar with thigmonasty, the touch-triggered response in the leaves of the popular Mimosa pudica plant. After all, it’s the go-to example for reflex actions in plants—alongside the venus flytrap.
However, nyctinasty is quite different from thigmonasty. The former is primarily caused by changes in light intensity, and the latter is a reaction to touch and vibrations. Still, both processes are plant reactions to variations in external stimuli.
It’s pretty easy to miss out on nyctinasty – which we also see in oxalis plants – since you’ll probably only see it at night. So, you’ll only notice it if you’re a night owl like me or in the habit of micromanaging your houseplants.
The nyctinastic process that causes calathea plants to perk or “stand” up is a result of the plants’ biology. Calatheas react to light in response to a blue-green substance known as phytochrome—a chemical similar to chlorophyll.
However, while chlorophyll allows the plant to photosynthesize, phytochrome oversees light absorption. The chemical also controls the growth and survival of your calathea plant.
So, your calathea plants can detect light with phytochrome—like human eyes do—and create diurnal cycles vital to the plant’s development. These cycles are similar to circadian rhythms, reacting to the quality of light your calatheas receive.
The pulvinus, a joint-like protrusion at the base of the calathea leaves, is a motor organ that regulates the nyctinastic response. Although the pulvinus isn’t typical of all plants, it functions in much the same way as muscles in mammals—pulling leaves and causing them to close.
So, you can relax next time you see your calathea plant standing with its leaves closed or perked up. It’s just getting some rest so it can have a fantastic day.
Mechanism and Purpose
Nyctinasty is a “sleep movement,” and its intensity depends on what plant species you have, as well as light intensity. And although it’s unclear what purpose nyctinasty serves in calathea plants, there are a few working theories that seem plausible.
According to some scientists, the plant is shielded from lower nighttime temperatures by its sleep movements, reducing the possibility of cold-related harm. Others believe that nyctinasty allows your calathea plants to conserve energy for daytime activities.
However, there is evidence that the activity boosts the likelihood that a calathea plant will successfully reproduce by helping to keep the plant dry. I’d argue that this argument might not work for your calatheas. After all, the plants don’t flower and produce pollen as houseplants.
According to another prominent notion, nyctinasty is a defense mechanism that protects animals from nocturnal pests and improves their ability to recognize nighttime predators. So, your calathea might be acting as it usually would in the wild—where it’s a commensal.
Another hypothesis makes sense: since your calathea plants use their leaves to capture water during the day, they need to perk up at night to allow this moisture to reach their roots. However, some scientists and gardeners argue that this theory might not be as strong as the rest.
The most likely reason for nyctinasty in calathea plants is that it helps them conserve energy during dormant periods. All plants are less active at night, so the perked-up leaves will ensure the calatheas don’t lose energy when they’re not getting sunlight.
Still, it’s evident that nyctinasty—regardless of its intended use—is a crucial and biologically effective trait for calathea plants. It’s also a lovely show and essential for a plant’s survival and growth.
Do All Calathea Species Perk Up at Night?
Calatheas are beautiful plants with prominent green leaves that can lift the mood of almost any space. No wonder they’re among the most popular home and office aesthetic choices. And since there are about 60 varieties of calatheas, it’s normal to wonder if all species of the plants perk up at night.
All species of calathea plants perk up at night. Nyctinasty, the response that triggers the plant’s leaf movement, is present in all calatheas. Therefore, you’ll notice closed-up leaves at night—and in low light—if you keep any calathea variety.
Remember, a perked-up calathea is a healthy calathea. And as long as you correctly care for the plant, you don’t need to worry.
However, the perked-up leaves could be an aesthetic problem if you live in a city that’s almost always cloudy. Fortunately, you can invest in artificial lighting to improve the calathea’s appearance and provide adequate light.
Remember to turn the grow light off at night or change the light settings so your calathea plant gets a chance to “rest.”
Common Reasons Your Calathea Isn’t Perking Up at Night
Your calathea plant should perk up in low light and at night but open during the day when it’s under sunlight. However, you might notice that your plant’s not perking up when it should—and this behavior usually means the plant is in trouble. So, what might be the reason your calathea’s not closing up at night?
Your calathea plant may not perk up at night because of:
- Too much light exposure during the day (if there’s artificial lighting nearby)
- Watering problems
- Extreme temperatures
- Diseases
- Pulvinus damage
- Dormancy
- Pests
I recommend you move the plant to a room with less light if artificial light affects it.
Watering inconsistencies, unsuitable water, overwatering, and underwatering can also affect calatheas and impair nyctinasty. Remember to water as appropriate, use clean water and monitor soil moisture content using a moisture meter. It’s an excellent choice for indoor and outdoor plants since it doesn’t need batteries to work.
Ensure the temperatures do not exceed 65 to 85 °F (18.3 to 29.4 °C), so your plant is comfortable.
And while pulvinus damage can also affect the calatheas, the plant will be fine—as long as the damage isn’t from diseases or pests. If you notice your plant is affected, you’ll need to deal with those first.
Key Takeaways
Calathea plants perk up at night because of nyctinasty. It’s a process that describes the movement of plant leaves in response to changes in light intensity. And while it’s a natural behavior, it’s vital to understand how it works so you can correctly care for your calathea plants.
This article is an excellent guide if you keep calatheas—or any nyctinastic plant—and need information on why they perk up at night. It’s also an excellent source of tips on how to care for calathea plants.
