Can Indoor Plants Grow Without Sunlight?

Many people want to grow indoor plants in their homes, but the lack of natural sunlight becomes a barrier to pursuing their hobby because the light is one of the most basic requirements for plant growth.

Natural sunlight is essential for plants to grow and make food. However, homes with little to no direct sunlight can also grow indoor plants with the help of artificial lights. These supplementary electric lights give the plants the required energy to grow and thrive in any lighting condition.

In this article, I will talk about the importance of light for plants, the different sources of artificial light, and how you can set up artificial lights in your home to help your plants grow.

Why do plants need light?

Light, along with water and air, forms the basic needs of plants.

Plants take water and carbon dioxide from nature and light from the sun and make their food, known as photosynthesis.

Photosynthesis makes plants capable of producing fruits, flowers, starch, and substances that are needed by other living organisms in the environment.

But unfortunately, in the case of indoor plants, not all homes get the required amount of sunlight for the plants.

Sometimes due to this, many plants suffer and end up dying.

But fret no more because, in this article, I will tell you everything about supplementary grow lights that can keep your indoor plants happy even in windowless rooms.

How to tell if the plants are not getting sufficient light?

The plant’s pattern can signal that it is not getting sufficient light.

The growth rate may reduce, the leaves will get smaller in size, the leaves will lose shine and gloss, the stems will get leggy, and the space between nodes will increase.

The three dimensions of light

The three dimensions of light are:

• Light intensity: Light intensity means the strength of the light that is mostly measured by foot candles. Foot candles measure the intensity of light. It measures the amount of light received by a one square foot surface 1 foot away from the light source.
• Light duration: The duration of the light refers to the hour or time the light source gives out the radiation.
• Light spectrum: The light spectrum is the wavelengths produced by the light source. Plants use 400-700 nm of light, including red, blue, and green wavelengths, to carry on with photosynthesis. 

Do plants grow better in sunlight or artificial light?

Certain plants can grow in artificial lights, but you need to know that artificial lights do not offer all that sunlight has.

Sunlight has the ideal balance of all the wavelengths that are needed for plants to get overall growth in their foliage, flowers, and fruits.

The sun’s rays have a free supply of photons, and the basic energy plants get from light.

All light sources, natural or artificial, are made up of these photons.

Artificial light is not that intense.

Thus we need to get the right kinds of lights to provide the plants with all the energy they need.

Therefore, supplementing artificial lights with some natural sunlight is highly recommended.

Also read: Do Regular Light Bulbs Help Plants Grow? (+Type Of Bulbs)

Sunlight vs. artificial light 

Although both the lights contain photons and can grow plants, there are a few differences:

• The wavelength of light: Artificial light does not have the required amount of red and blue wavelengths needed for the growth of plants that the Sun has. 
• The intensity of light: Sunlight is much more intense than artificial light. It means plants get more access to photons and can carry on photosynthesis better.

How much light do the plants need?

The amount of light each plant needs varies as per their requirement.

Indoor plants are generally divided into three categories – low light, medium, and high light.

• Low light plants: Plants that need at least 50-250 foot candles are referred to as low light plants. They need 20 watts 2 feet long fluorescent tubes in artificial light conditions.  
• Medium-light: These plants need between 250-1000 foot candles. In this range, the best growth in the plants is seen above 750-foot candles. A setup with two fluorescent tubes can be sufficient for these plants.
• High-light plants: Ideally, high-light plants should not be grown indoors, especially under artificial lights. If your home has a lot of full sunlight, you can grow them. They need at least 1-000 foot candles at the least. Fixtures with three-four lights are a necessity for them.

Also read: What Does Bright Indirect Light Mean For A Plant?

Impact of artificial lights on the growth of a plant

Artificial lights provide plants with the necessary energy.

However, in certain cases, the plant might show certain warning signs.

A study had shown that lettuce grown under red LED lights had a more elongated stem than the ones that grew in natural sunlight.

However, this was corrected when some blue lights were added, preventing the stem’s leggy growth.

Besides the growth, the molecules were also affected by artificial lights. 

So chlorophyll is the main molecule used by plants to trap the photons and prepare food.

A study found that chlorophyll worked slower under red and white LED lights than how it works in natural sunlight. 

Is the color of the lights important to plants?

There are lights in different color spectrums, each having qualities, but only certain colors are important for plants.

The green or yellow wavelengths do not give much energy to plants as they reflect the light but the red and blue wavelengths of light are vital for plants as they derive all the energy from these lights.

So you have to understand each light’s different wavelength types to get the right balance of wavelengths.

Blue wavelength light is suitable if you want to grow the foliage.

Red wavelength helps plants to get the energy to produce fruits and blooms in their plants.

Plants that grow outdoors, in natural sunlight in greenhouses, get access to balanced wavelengths in the light from the sun.

But in artificial settings, it is impossible, so you need additional and supplementary lights to get all the necessary wavelengths to the plants.

Types of artificial lights available 

So if you intend to invest in artificial lights to grow your plants, you need to know about the various types of artificial lights that you can choose from: 

Fluorescent lights

These are the most affordable and popular options for houseplant owners.

These lights come in tube forms or compact bulbs that you must screw into the sockets.

They stay cool, so keep your plants near them without fear of burning the foliage.

They are high in blue wavelengths, so while buying them, choose the mix of cool and warm bulbs or look for the full spectrum options.

You can buy the cool white shades because they contain the full spectrum.

Place the plants 1 foot away from the light source for best results. 

Incandescent lights

These lights give out more heat than the former ones and thus need to keep a distance from the plants, reducing the light’s intensity.

They give out higher radiation of the red wavelength and thus can be used to supplement fluorescent lights to get a balanced spectrum if you are trying your plants to bloom or produce fruits.

If you intend to mix the two to get the best results, get 1/3 incandescent and 2/3 fluorescent light watts.

But as a single light source, incandescent lights are not suitable, and a standard light bulb lifespan is just about 1000 hours compared to fluorescent bulbs, which average 10,000 hours. 

LED lights

LED lights are the newest source of supplementary lights.

They also emit lower heat, are extremely long-lasting and are energy efficient.

Many varieties of LED lights are available, so buy the ones that produce red and blue wavelengths necessary for plants and have a much higher intensity than fluorescent light.

Among all the varieties of artificial lights, LEDs are probably the best. 

However, they are more expensive than other light sources.

High-intensity or gas discharge (HID) lights

HID lights are often used in greenhouses to give supplementary light when needed.

They are quite an energy efficient in covering the electrical energy to light than incandescent lights.

The bulbs are long-lived but give off too much heat, and the fixtures required to hold them can be quite bulky and expensive. 

Horticultural grow lights

These come in mostly tubes and have a full spectrum wavelength needed for plants to bloom like African violets.

Also read: LED Vs. Fluorescent Grow Lights (Pros & Cons+Best Picks)

6 FAQ you must know about using artificial lights on plants

Before you decide to use artificial light on your plants, you must know these facts so you don’t make any mistakes.

Also read: How To Use Grow Lights For Indoor Plants?

1. How far from light should plants be kept?

There should be a 6-12 inches distance between plants and the light source.

The intensity of the light reduces as the distance increases.

The ends of fluorescent tubes produce a lot less light intensity than the tubes’ center, so the spot directly under the center is the brightest and has the highest intensity. 

2. How long should I use the artificial lights?

Plants with no access to natural light and solely dependent on artificial lights should get lights for at least 16 hours every day.

If there is additional exposure to outdoor lights, 12-14 hours of light will be sufficient.

But you should turn the lights on simultaneously when the outdoor lights fall on the plant.

3. How to get the most from artificial lights?

Reflective surfaces can maximize the impact and efficiency of the lights on the plants.

There are porcelain-coated reflectors that are very helpful, but it requires daily cleaning to keep them dust free as dust reduces the effectiveness.

You can also put aluminum foil or white paint on the surface so that light reflects around the area.

Remember not to keep the plants too cramped together as that would shade one plant from another and will not allow light to pass. 

4. The most popular light source for interior settings

Due to their energy efficiency and modest pricing, fluorescent lights are most popular indoors among most gardeners.

Cool white tubes are mostly a favorite, but warm white does the job.

But the tubes marked as daylight or white are ineffective for plant growth.

The cool white tubes produce a little red wavelength and some orange, green, and blue rays, which are not enough for plants unless there is a source of natural light or other artificial lights to supplement the red wavelength.

You can use a few incandescent bulbs alone to give the needed red wavelengths to plants.

On average, the ratio of incandescent to fluorescent is about 3 to 10, which means for every 100 watts o fluorescent light, you need to add 30 watts of incandescent light for a balanced red and blue light exposure.

Recently, fluorescent tubes, especially for growing plants, have been developed in the market.

They have a higher output of red light to balance the blue.

Many gardeners have started using these tubes along with cool whites because this method is more economical as these tubes are more expensive than cool white tubes.

The plant growing tubes also use less electricity and less heat.

Below is one example of a lighting setup for your home.

• Get a tall lamp with three holders, preferably one with moveable fixtures.
• To get an overall plant growth, including foliage and blooms, get the highest wattage of one incandescent bulb with two fluorescent bulbs or one plant growing tube.
• Position the lights towards the plant table. If the light fixtures are movable, put the fluorescent lights closer than the incandescent ones to protect the plants from heat damage.
• Try to place a mirror beneath the plants, reflecting the light into the foliage.
• Keep this lighting set up for 16 hours daily. 

5. The best window for light

Even when your plants are getting artificial light, some form of natural light is important for plants.

If there is any window in the room, let the natural light from the window fall on your plants.

Trees or other buildings do not shade the ideal windows.

South-facing windows provide the brightest light for the longest duration and are ideal for high light-requiring plants.

Plants needing bright medium might do well in east-facing windows as the light is not scorching, and low-light plants do just well in north-facing windows. 

6. Pros and cons of using artificial lights to grow plants

• The main benefit of using these lights is that they enable us to grow plants, even in homes with little natural light.
• You do not solely depend on natural lights to grow your plants. So in winter or rainy seasons, your plants are still happy and thriving in light when the sunlight is poor.
• You can tweak the lights according to the requirement of the plant. Like red lights to make your plants bloom.
• One drawback with artificial lamps is that they will impact your power bill, especially if you use incandescent bulbs. Though LED lights are much more power efficient, they do cost you for installation.
• Another problem is that if you are fully dependent on artificial lights, your plants will suffer in case of power failure. 
• There are also chances of electrical mishaps with so many lights turned on for such long dictions. 

Plants that thrive in indoor lighting

• Arrowhead plants are bushy climbers, can tolerate low light, and do fine in artificial lighting.
• African violets are one of the best plants that flower under grow lights, between 500-1000 foot candles for 16-18 hours daily. 
• Begonia thrives in medium lights for a long duration, from 14-18 hours daily.
• Ferns do well in artificial lights.
• Spider plants are suitable in the medium-light range and do well in indoor lighting.
• Cast iron plants do well in poor light conditions. 
• The Chinese evergreen species can tolerate as low as 10bfoot candles, but the best growth and variegation occur in medium light.
• Dracaena, dieffenbachia, the different species of ferns grow satisfactorily in indoor lights. 
• Palms grow well in medium indoor lights.
• Snake plants can tolerate low lights just fine.

Final words 

Nowadays, with so many of us living in apartments with very little open space, gardening is a challenge due to poor natural light. But I have discussed that you can supplement the light with different artificial lights that have recently become so popular.

However, remember sunlight is the best energy source for every plant, so try to give your plants access to both light sources for the best growth. 

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Sources: University of Minnesota, David H. Trinklein, Horticulture State Specialist, The University of Georgia, The Royal Horticultural Society.