Have your Calathea plants turned yellow foliage, or have leaves lost their evergreen colors? Don’t take it as normal features of variegated Calathea, as this can be a result of improper lighting.
So, you need to inspect the place to see if your Calathea can access optimum light.
Generally, Calathea needs 8 to 10 hours of medium bright light with 10,000 lux or 1000-2000 foot-candle for optimum growth. It also prefers an east or west-facing window to receive sunlight and artificial lights when the sun is away.
You can also consider the leaves of Calathea to appear faded and translucent to check the light availability.
If you wait any longer now, you may lose your dear plant, so digest all the light requirements through this article!
Table of Contents
Overview of Calathea Plant
Calathea boasts luscious, dark green leaves that feature scalloped edges and silver brushmarks on the top of the leaves.
Calathea possesses 70 varieties and if you want to learn some popular varieties, be a guest of 20 Stunning Calathea Varieties.
Let’s look at the brief overview of Calathea.
|Common Name||Prayer Plant|
|Native||South American jungle|
|Foliage Feature||Thick and intricately patterned leaves up to 2 feet wide
|Flower Profile||An asymmetrical structure with 3 petals and 3 free sepals|
|Blossom Color||Yellow, purple and white|
|Blooming Period||Spring and summer|
|Plant Growth||About 2 feet in height|
How Much Light Does Calathea Need?
Calathea grew under the canopy of trees in its natural habitat to leverage indirect lights.
Generally, Calathea needs bright indirect, filtered light and can also adapt to artificial light if natural light is unavailable.
These tropical plants grow best in a shady room, so you can insert them into your bedroom, kitchen, or place where there is no hot, dry air.
On an average, the houseplants survive from 4 to 20 days without light and as a low light plant, Calathea can live between 12 and 20 days without the light exposure.
How to Ensure Optimum Light for Calathea?
Calathea is a tropical plant that requires medium, indirect sunlight and enjoys a few shady places. If you have any queries regarding the lighting condition for Calathea, consider the following!
1. Light Intensity
Generally, light intensity depends on the distance of the light source from the plant and reduces rapidly when increasing distance and vice versa.
According to research from the University of Florida, Calathea needs 10,000 lux or 1000-2000 foot-candle for its optimum growth.
If there is not enough light source, Calathea may need at least 200 foot-candle (40 µmol) to survive, and 400 FC (80 µmol) can be enough for good growth.
Further, if you want to grow them commercially, 1000-2000 FC (200-400 µmol) of light is required.
According to the International journal of Agriculture and Biology, when the light intensity decreased, the intensity of pigments in the coloration of inflorescence increased and became more luminous in Calathea Crotalifera.
You can use a light meter to ensure your Calathea gets the correct light intensity. To measure the light intensity, hold the light meter close to the leaves in the direction of the light source.
2. Light Duration
Light duration represents the photoperiod or the number of continuous hours of light in each 24 hours period, in which photoperiod regulates flowering in many greenhouse crops.
Generally, Calathea requires at least 8 to 10 hours of bright, indirect light each day, followed by 8 hours of darkness.
However, they can also tolerate 1-2 hours of direct sunlight, but more than that can get them sunburn.
You can provide the same amount of light during winter using a grow light, not more than 16 hours in duration.
3. Light Quality
Light quality is the relative number of blue, green, red, and far-red photons emitted from a light source, and wavelengths of light give different light colors.
the light quality received by your Calathea will determine its growth, and generally, the plant thrives in red and blue content and lower yellow content.
Calathea needs a combination of blue(430-500 nm), far-red(740-800 nm), and red(625-740 nm) wavelengths for better growth.
Similarly, the red light will help Calathea to promote photosynthesis, whereas blue light encourages richer color in the foliage and with root and stem growth.
On the other hand, far-red light helps with the germination and seedling process of your Calathea. Calathea needs a color temperature ranging from 4000 to 6000 kelvin as an indoor plant.
If you are unaware, you may need to read best color for the plant’s growth.
4. Location for the Plant
Calathea, a tropical plant grown in the canopy of big trees in its natural habitat, needs to be placed where it gets plenty of indirect sunlight.
Thus, keeping your calathea near the east or west-facing windows is best.
The eastern-facing windows will not be harsh to your Calathea as it will get morning sun with less intense light.
Similarly, western-facing windows will also offer enough light without damaging the plant.
However, when keeping near the south-facing windows, use sheer curtains to protect Calathea from harsh direct sunlight.
Additionally, if you have large enough space, you can keep them four feet away from the south-facing windows to ensure the right level of light intensities.
Look at the table below to find different locations with different light intensities.
|Light Intensity||Footcandles||Light Exposure|
|Low-medium||25 - 400||North-facing window|
|Medium-Bright||500||East-west facing window|
|Bright-High Light||500 - 1000||South-facing window|
|Direct Sunlight||Over 1000||4-6 hours of direct sunlight|
Besides, you can also place these plants on patios, porches, and outdoors with enough shades.
Signs of Light Deprived Calathea
Your Calathea might show the following symptoms if it does not get adequate light.
- The leaves will appear paler green leaves with indistinct markings.
- The plant will be leggy as it will produce less energy.
- The soil will appear wet as the transpiration cannot take enough water.
- Drooping, curling, and wilting of foliage can be prominent.
- Calathea will start leaning toward the window in search of a light source.
- Light deficiency will hamper the photosynthesis process resulting in stunted or no new growth.
Signs of Light Saturated Calathea
As Calathea favors indirect sunlight, getting them exposed to bright light will show various signs.
- Brown and black spots on the edges of leaves.
- The plant detects sunburn, and leaves will start turning yellow.
- Your plant’s foliage and flower will start discoloring.
- Leaves will start folding as they require lots of water due to excessive evaporation.
- The soil will be dry and will cause underwatering consequences.
- Leaves will be dry and crispy from excess heat.
Does Calathea Grow in Artificial Light?
If you live in a darker apartment with no sign of 8-10 hours of bright indirect light, you can use artificial light.
Calathea prefers artificial light with 15 to 20 watts or equivalent.
There are various types of grow lights for houseplants, and you can easily choose one for your Calathea.
- Incandescent: These lights are a rich source of red light but a poor source of blue and produce excess heat.
- Fluorescent tubes: They emit both blue and red light and produce less heat.
- High-intensity discharge lights: These artificial lights emit a lot of heat, and the fixture needed to operate them are bulky and expensive.
- LEDs: They are energy-efficient and produce red and blue lights.
I recommend using LED lights as they have a long life span and can also be customized to produce the wavelengths of light your Calathea requires.
You opt either for Cool White (6500K, 6000K, 5000K) or Warm White (4000K, 3000K, 2700K, 2000K) when inserting grow lights for Calathea plants.
In addition, it produces red and blue light needed by the plants for healthy growth. You must put the plant a foot away from the light without harming it.
Take a look at the table to know where you can place your Calathea!
|HID Grow Lights (400W)||12”-19” away from the plant|
|HID Grow Lights (600W)||14”-25” away from the plant|
|LED Grow Lights (240-400W)||16”-30” away from the plant|
|LED Grow Lights (450-550W)||20”-30” away from the plant|
|CFL (200W)||6”-10” away from the plant|
However, do not substitute sunlight for artificial light as sunlight will always be superior. Also, you should not allow artificial lights on your Calathea for more than 16 hours.
I have also listed grow lights which you can easily buy from Amazon for your Calathea.
|Grow Lights||Feature||Product Image|
|LED Grow Light for Indoor Plants - Relassy 75W||Provides all the wavelengths of light between 380nm - 800nm|
Adjustable light intensity
|GooingTop LED Grow Light||Energy efficient|
Timer function of 4/8/12 hours
|Lxyoug LED Grow Lights||Provides blue, red and white color temperature|
Auto circular memory timing function
|Yuanhui YH2400 Led Grow Light||Provides 3000K warm light color, 5000K daylight color|
660nm increasing deep red color and 730nm far red diodes
Calathea is a low-light lover who thrives well in medium bright light and little shade. You can save your Calathea from multiple unhealthy symptoms with little effort with lighting requirements.
I have tried to cover all queries regarding Calathea light feedings so that you can leverage all that your Calathea can offer.