Do not mistake the yellowing evergreen foliage of Calathea as a standard feature of variegated Calathea, as it could be because of improper light requirements.
Besides that, Calathea shows various signs when you fail to meet its ideal light requirements. Thus, continue reading till the end, so you know the ideal lighting for Calathea.
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How Much Light Does Calathea Need?
Calathea grows under the canopy of trees in its natural habitat, so they prefer indirect lights.
These tropical plants grow best in a shady room, so you can place them in your bedroom, kitchen, or place where there is no hot, dry air.
Houseplants that tolerate low lights can survive from 4 to 20 days without light.
Calathea is also a low-light houseplant, so that it can live without light for about 12 to 20 days.
But utter darkness with no other artificial light will push back the growth and cause light-deficient issues.
How to Ensure Optimum Light for Calathea?
Native to Brazilian rainforests, Calathea can thrive flawlessly outdoors under the shade in 11 to 12 USDA zones.
You can consider these factors to mimic the natural habitat-like light for optimum growth of Calathea.
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.
Calathea needs at least 200 foot-candle (40 µmol) to survive, and a light intensity of 400 FC (80 µmol) is enough for good growth.
Further, if you want to grow them commercially, 1000-2000 FC (200-400 µmol) of light intensity is much preferred.
Do not get overwhelmed with technical terms! You can use a light meter to measure light intensity.
All you got to do is hold the light meter close to the leaves in the direction of the light source.
2. Light Duration
For ideal growth of the Calathea, ensure at least 8 to 10 hours of daily bright, indirect sunlight followed by 8 hours of darkness.
Thus, incorporate them in the east window to boost lustrous green foliage. Meanwhile, they may tolerate at most one hour of the afternoon sun.
You can provide the same amount of light during winter using a grow light for about 10 to 12 hours.
3. Light Quality
The light quality received by your Calathea directly influences plant growth.
Most houseplants generally thrive in red and blue content and lower yellow content.
Red light helps with photosynthesis, while blue light makes foliage more pronounced and encourages root and stem growth.
Meanwhile, far-red light helps with the germination and seedling process of your Calathea.
Aim for 4,000k to 6,000K light color temperature for your indoor Calathea.
4. Location for the Plant
The light intensity varies according to location, so you must consider location before placing Calathea.
Also, keep them at least 3 to 4 feet away from the window to protect them from direct sun exposure.
Look at the table below to find different locations with different light intensities to fulfill ideal Calathea light requirements.
|Light Intensity||Footcandles||Light Exposure|
|Low-Medium||25 - 400||North-Facing Window|
|Bright-High Light||500 - 1000||South-Facing Window|
|Direct Sunlight||Over 1000||South or West-Facing Window|
You can also place these plants on patios, porches, and outdoors with enough shade.
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 with indistinct markings.
- The plant growth will be leggy due to a lack of energy.
- The soil appears 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.
- Leaves will start turning yellow.
- Foliage and flower will start discoloring.
- Leaves will start folding as they require lots of water due to excessive transpiration.
- The soil will be dry and will cause underwatering issues.
- 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.
There are various 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: 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.
LED lights have a long life span and can be customized to produce the wavelength Calathea prefers. So, many gardeners suggest LED grow lights.
Nonetheless, keep Calathea at least a foot away from the grow light to prevent potential harm.
However, do not substitute sunlight for artificial light as they can not fulfill all light requirements of Calathea as the sun does.
Here are some best artificial grow lights for your Calathea plant.
|LED Grow Light - Relassy 75W||Provides all the wavelengths of light between 380nm - 800nm
Adjustable light intensity
|GooingTop Grow Light||Energy efficient
Timer function of 4/8/12 hours
|Lxyoug LED 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
Despite being low light, Calathea needs natural sunlight to thrive and sustain its thick, intricately patterned leaves.
Calathea will stay upbeat with proper lighting and produce blooms of yellow, purple and white in spring and summer.