How Does Artificial Light Help Plants To Grow?

Have you ever thought about using artificial lights to grow plants?

It is possible to grow plants indoors with artificial light until they are fully grown. Whether or not this kind of cultural method is worth it is a different question.

But the problem is not that there isn’t enough artificial light to make up for the lack of sunlight. Whether this is your first garden or you have a green thumb, you should think about where it can get light. You might not get much sunlight if you live in a small apartment or in a city with a lot of clouds.

So you might want to think about other ways to light the room. Artificial light can help plants grow, but not all artificial light is good for plants. Grow lights are artificial lights that are made to give off the specific colors (wavelengths) of light that plants need to grow well, which is the mostly blue and red light.

If you want to grow a plant inside, especially in a place with low light, you should think about ways to use artificial lighting. Even though the sun might work for plants near windows, plants can also grow with the help of artificial light.

Read on to find out more about how to grow plants using artificial light.

What do plants need? 

It’s not true that plants need the sun to make food through photosynthesis.

Photosynthesis comes from the Greek words “photo,” which means “light,” and “synthesis,” which means “putting together.” In other words, plants don’t need sunlight to make food; they need light. Photons, to be more specific, are what they need.

Light is made up of tiny particles called photons, and each photon has a certain amount of energy. This amount of energy is called photon energy. When a photon hits something, like a plant, it gives that thing some of its energy.

The sun’s rays are a free source of photons that have been around since the beginning of life. Eventually, life found a way to use this abundant energy source to stay alive. Some of the organisms that did this were plants, which evolved from the first photosynthetic algae.

Many billions of years after the first organisms that used light to make food appeared, humans showed up and figured out how to make our own light. After a very long time, incandescent light bulbs came after the fire. No matter if the light comes from thermonuclear fusion or a chemical reaction, all light is made up of photons.

So, your plants will still grow with the help of artificial lights!

Sunlight versus man-made lights 

Still, there are some things you shouldn’t do if you want your money plant to grow strong and healthy.

Even though your plants can grow with artificial light, there are some important differences between the light from the sun and the light from a bulb.

• The length of a light’s wave – We know that white light is made up of all the colors of light, but there are still small differences in the wavelength of white light. The sun has more red and blue light than any other source of light. Different lengths of light have different amounts of energy in each photon. Most of the red and blue light that hits green plants is absorbed, while most of the green and yellow light is reflected (which is why plants appear green).
• How bright the light is – Sunlight is brighter than any other kind of light. Plants are best able to handle this higher level of sunlight. The higher intensity also means that the plant gets more photons and can photosynthesize better because of this.

Can plants grow with lights that aren’t the sun?

Plants can grow with artificial light, and under the right lighting conditions, they can grow well. Even though sunlight is great, you don’t need it to have a successful indoor garden. You don’t have to sacrifice growth if you want to move your plants away from your windows.

So, if you want to give your plants more light than what they get from the sun, you could add artificial light or grow light.

Grow lights are a type of artificial light that is made to help plants grow. This means that the lights give off the right colors (wavelengths) of light to help plants grow healthily.

And yes, plants do respond to the color of light.

LED, fluorescent, and other types of artificial light can be used. Think about how many plants you want to grow and where you want them to go. So, you can decide what kind of artificial lighting will work best for your plants.

With all the different kinds of grow lights available, you can read our full article on how to use grow lights in a home or greenhouse.

Effects of man-made light on plants 

Artificial light might be enough to meet a plant’s needs for photosynthesis, but plants also use light signals to keep track of how they are growing and working.

Like animals, plants have an internal biological clock that is timed by the way the sun moves during the day. Sunflowers move with the sun throughout the day because of this biological clock. It also controls when flowers bloom and how tall and long plants grow.

According to research, when lettuce was grown in red LED light, the stem grew longer than when it was grown in white light. The stem grows because of how much light it gets. Researchers also found that adding some blue light kept the stem from growing too long.

Artificial light also changes the molecules that plants need to grow and make food from sunlight.

Chlorophyll is the main molecule that plants use to get energy from photons. The amount of chlorophyll in a cell depends on how much light there is. Researchers found that under white LED light and red LED light, chlorophyll builds up slowly, but not under blue LED light, where chlorophyll production was not changed.

Other molecules in the plant that don’t have anything to do with photosynthesis are also affected. The plant makes these molecules do other things, like act as antioxidants or hormones.

These molecules, which are called secondary plant metabolites, are often very important for the nutrition of animals. Research on the medicinal plant “cat’s whiskers” (Orthosiphon stamineus) showed that important secondary metabolites dropped when the plant was exposed to artificial light with high irradiance. Irradiance is a measure of how much energy light gives off.

This suggests that the amount of light might be an important thing to think about.

Which is better for a plant to grow: sunlight or artificial light? 

I’m not a scientist, so I can’t give you a scientific answer.

Plants have very different needs in terms of how much light they need. Some tropical plants, like the iron plant (Aspidistra elatior, cast iron plant), can live in light as dim as that from 50-foot candles.

Even more sensitive is how other plants decide when to flower. Even a one-foot candle can change how a plant responds and make it flower or stop it from flowering, depending on whether it is a long-day plant or a short-day plant.

Still, other plants need 7,000-foot candles or more and won’t bloom unless they get full sun.

Photosynthesis needs the full spectrum of light that comes from the sun. I would think that if you could give me blue light, red light, and everything in between, you could give me the whole range of light. It wouldn’t change anything.

But I will say that I’ve seen some beautiful pothos and African violets grown indoors with the help of artificial lighting.

Read More: Bermuda vs St. Augustine grass

How does light work and what do plants need? 

Strangely, warm-weather plants can handle less light when it’s hotter than cool-weather plants can. If they don’t get extra light, plants that need low temperatures, like cinerarias and calendulas, will suffer more in a dark room with high temperatures than the poinsettia.

One problem with using artificial light to grow plants has been that incandescent light bulbs give off a lot of heat. Most of this problem has been taken care of by fluorescent-grow light bulbs. Fluorescent bulbs can put out a lot of light while putting out less heat.

Still, there are three “dimensions” of light:

• The amount of light – light intensity,
• Duration – how long it stays on
• Lighting spectrum – the color of the light

Light intensity is the measure of how bright the light is. It is usually given in foot candles. Photographic light meters are often measured in foot candles, so this term isn’t as hard to understand as it used to be.

People often get duration and intensity mixed up. The duration is the number of hours that the light source shines, but intensity and duration are not the same things. You can’t make up for a short day by having brighter light for less time.

There is some evidence that African violets can grow just as well with 600-foot candles for 18 hours as they can with 1,000-foot candles for 12 hours, but this is about the only time that the two qualities are not interchangeable.

Full-spectrum fluorescent bulbs can be used for as long as they are needed. Another problem is the amount of light. Because the radiation from these full-spectrum light bulbs or fluorescent tubes doesn’t “project” well, plants (leaves) must be placed within 12″ of the light fixture to get enough “grow light.”

Because of this, a standard light fixture with two 40-watt fluorescent tubes can only light about 4 square feet of growing space, which is about 12 inches wide and 4 feet long. On the other hand, incandescent bulbs can be hung three feet above the plants. When used this way, one 60-watt bulb can replace the sunlight in a four-foot-by-four-foot area.

But this statement shouldn’t be taken to mean that fluorescent lights or incandescent bulbs can be used all the time to replace natural light from the sun. For many species, this kind of light can be used as an extra source of light.

If the plant starts to flower when the days are shorter, this extra light can help to slow it down. If it needs long days to bloom normally, the extra light could make the difference between flowers and none.

In the case of the poinsettia, for example, the fact that the living room is used at night is the reason why this plant usually doesn’t do well there. Just two or three-foot candles’ worth of light from sun lamps on plants is enough to stop them from flowering.

When someone in the family reads a magazine, iPad, or Kindle while the living room lamp is on, you can’t expect a poinsettia to bloom in that room. Before it can bloom, it needs to be completely dark for at least 13 to 14 hours a night.

Even though chrysanthemums are also short-day plants, they are often kept in check by giving them more light until late winter. When you want flowers, you turn off the lights, and the plant blooms. So, chrysanthemums can be made to bloom whenever the grower wants by giving them shade in the summer and light in the winter.

What amount of light do plants need to grow?

Not all plants need as much light as others.

For example, some ivy plants and ferns have adapted to growing in the shaded understory of a forest. These are definitely low-light plants.

On the other hand, plants like tomatoes, okra, and cactus have evolved to grow in places with a lot of light. If you grow them indoors, they will often need extra light.

Even though the amount of light doesn’t change much between sunlight and artificial light, you should think about what plants you have or want. Low-light plants need about 3–4 hours of sunlight per day, while high-light plants need much more, around 12–14 hours per day.

Plants that don’t need much light

Low-light plants only need enough light to read the newspaper. Many of these plants have leaves, which are more important than flowers. If you don’t have a lot of space or don’t want to use a lot of artificial light, these plants are a good choice.

Think about the following plants that don’t need as much light:

• Peace lily
• English ivy
• Lady palm
• Arrowhead plant
• Chinese evergreen
• Snake plant

These plants often grow under the branches of bigger plants. So you don’t have to worry about giving these plants a lot of light. They can still grow well, though.

Plants for medium-light

Medium-light plants do well with indirect sunlight, but they can also do well with about as much light as fluorescent lights. Think about a few of these plants:

• Elephant ear
• Ferns
• Spider plant
• Flame violet
• Asparagus fern
• Kad plant

Many of these plants can be grown indoors without a lot of extra lighting. But you can use different kinds of lights if you don’t want the whole room to be bright all day.

Plants that grow well in bright light

Many plants that bloom need a lot of light. You can grow these plants in a window, of course. But you can also help them by giving them enough light from a lamp or window.

Here are just a few:

• Hibiscus
• Citrus
• Succulents
• Poinsettia
• Geraniums
• Orchids
• Cacti

You can still grow these plants even if you don’t have a lot of sun. You can have a thriving indoor garden as long as you look for the best artificial light.

How Do plants grow under different kinds of artificial light? 

An artificial sunlight lamp can be used for more than one thing by a beginner grower. One of the most interesting things to do is to make tuberous begonias bloom in the winter when it’s dark and cold outside.

The tuberous begonia needs more light because it has long days. When the day is less than 12 hours, it stops making flower buds when it is out in the open. Around the middle of September, tuberous begonias stop flowering and start making bulbs instead.

At Cornell University, they found that if lights are put on the plants right before this happens, around mid-August, the tubers don’t get bigger and the plants keep blooming all winter.

Either fluorescents or incandescents can be used to light indoor plants by turning them on at 4 p.m. and turning them off at 9 p.m. With a timer like this, it’s easy to do.

Many indoor plants, like geraniums, Browallia, Heavenly Blue morning glories, and others, can stay in bloom all winter long with the help of this extra lighting. If you give plants artificial sunlight, the leaves of plants like Coleus that need bright light will stay short and strong. English ivy won’t try to reach for the sky anymore, and it will still have short joints.

This isn’t really the same thing as growing plants with only artificial light. How far we can go in this direction depends on how much money we can invest. I’ve seen artificial lights that were 50% brighter than daylight, with air conditioning to cool down the room because the lights gave off so much heat.

But most amateur gardeners don’t have the skills or money to make such designs.

Different kinds of grow lights for plants inside 

There are different kinds of grow lights for plants that are kept inside. I’ll show you how to choose to grow lights for your indoor plants so that your plant gets the best conditions for the least amount of money.

Incandescent lamps

You shouldn’t use this kind of bulb to give plants light.

• First, their spectrum doesn’t have any blue spectrum waves, which are very important for the process of photosynthesis.
• Second, these lamps get very hot, which means that if you put them close to plants, they can burn the leaf plates.
• Third, the efficiency of these lamps is very low, at only about 5%. The lamp itself isn’t very expensive, but if you want to use it for a long time, it will cost you a lot of energy.

Small greenhouses can have both an incandescent bulb and a fluorescent lamp. There is a small amount of red light coming from the fluorescent lamp. Also, incandescent bulbs will heat the air even more.

Fluorescent lamps

Fluorescent lamps don’t heat up nearly as much as incandescent lamps. So, they don’t change the temperature of the room, so you can choose them to give your plants artificial light. You will get a lot of light (although over time it tends to decrease).

Because they use less energy, you’ll save money on your utility bills. Fluorescent phytolamps are the best choice for lighting large plants.

Because of how big they are, you can’t put them on a window sill or other small space.

You may now be wondering if you can use regular lights on your plants. Normal fluorescent lights can’t be used for this because their red waves are too weak.

Plants can’t use the weak waves to help them make food. You should buy fluorescent lights that are made for plants and give them the spectrum they need.

Using lamps with directional reflectors can make them 25–30% more efficient.

Mercury lamps are also called fluorescent lamps because they work similarly. But the red part of the spectrum is much bigger in them. But mercury lamps use more electricity than fluorescent lights.

Energy saving lamps

Energy-saving lamps give off blue light, so you can use them for plants that don’t flower. These are similar to fluorescent phytolamps in most ways.

This kind of lamp is very easy to set up. To connect a light bulb, all you have to do is screw it into a standard cartridge.

Another benefit that can’t be argued with is that energy-saving lamps use much less electricity than fluorescent or incandescent lamps and last much longer (up to 15,000 hours).

There are three kinds of photovoltaic lamps that save energy:

• “Cold”: You can use this to speed up germination and growth of seedlings during the time when they are actively growing leaves.
• “Warm” lights are best for lighting plants when they are blooming.
• “Daylight” can be used at any time and can be used as an independent (additional) light source for the plant’s entire life cycle.

Sodium lamps

When you look at how much light they give off, sodium lamps are one of the best. It is cheap and works very well.

With a medium-power photo lamp, you can easily light plants on a 1.5-meter-long window sill.

These lights last a long time (up to 20,000 hours) and are easy to use. Most of its light comes from the orange and red parts of the spectrum are where most of its light comes from.

Your plants will flower faster if there are enough blue waves and a certain number of sodium lamps. The downside is that it will cost a bit more for your pocket. With just one 220 W ceiling lamp, you can light up a pretty big room.

LED lamps

If you want to make a light schedule for plants, LED lamps are the best choice for you in every way:

• They use the least amount of power and work well.
• One LED lamp can work for up to 50,000 hours.
• They are small, so they can be used to light plants on shelves. Herbal tape plants can be grown with LED.
• LED lamps can make waves in the useful spectrum (red, blue, orange). You can actually control how the plant grows by speeding it up or slowing it down. This means that you can use less energy.

Choosing the right power for a photo lamp is just as important as choosing the right type. For a 1 m2 area, you should use a 70W lamp.

Also, keep in mind that the effect of the light on the plant will be bigger and fuller the closer the light is to the plant.

You should think about how thermal radiation can hurt you. So, the best distance should be between 20 and 25 cm. You can put the LED lights close to the plants because of how they work.

Because LED lights don’t make much heat, they can also be put below.

Light is an important part of the process of photosynthesis in plants. Grow lights can still help you grow plants even if you don’t have access to natural light.

Fluorescent bulbs

Fluorescent bulbs are very efficient, just like LED lights. A coating on the outside of the bulb filters the electricity that goes through the mercury particles. These lights are great for growing plants inside because they give off a steady, cool white light.

A few long-shaped fluorescent bulbs above the plant will do the best job of making it look like it’s outside. Plants have grown to be able to take in light from the sun, so all of their leaves face up. If the light is not coming from directly above, the plant may grow in an odd shape.

If you put fluorescent light bulbs high above the plant, it will grow just like it would in the open air. You don’t want your plant to have to turn all its leaves to one side to get light.

Halogen bulbs

Halogen bulbs are like incandescent bulbs, but they have a tungsten filament instead of a wire filament. A halogen, such as iodine or bromine, wraps around the filament. The result is a bulb that uses less energy to give off more heat.

This can help you grow plants since a lot of plants that grow in warmer climates need heat. Halogen bulbs are actually being phased out all over the world because people think they don’t work as well as they could.

A halogen bulb needs about 29 watts, which is 11 less than an incandescent bulb. This is enough light for a square foot of plants.

Hydroponic bulbs

Today, LEDs are used to make these kinds of bulbs. They are the kinds of bulbs used to grow plants in factories, and they do a very good job of imitating the sun. Hydroponic bulbs are much brighter and stronger than regular bulbs, and they give plants a wider range of light.

Hydroponic bulbs are not usually part of a home’s lighting, but they are easy to find and buy at hardware stores or online. They use the same source of power as regular lights, but they need more power.

Many hydroponic bulbs say they are as strong as the sun during the day and give plants enough light to turn into energy. Just don’t forget to turn them off at night, since plants also need time in the dark.

Indoor Grow Light Best Sellers 

• Fluorescent Grow Light System with Stand Rack for Seed Plant Starting
• Indoor Grow Light System with 3-Tier Stand SunLite Garden Light with Plant Trays
• High-Pressure Sodium Lamp by Sun System (HPS)
• T5 Grow Light – 2 FT 4 Lamps by Durolux

Using artificial light to grow plants indoors in the basement

Some plants, like African violets and Venus fly traps, can grow in a basement using only artificial light. We call all of these “forest floor” species.

They are plants that have learned to live under trees in a forest, where there isn’t much light. This group of plants includes African violets, plants that eat other plants, all begonias, browallia, impatiens, and a lot more. If a species can grow and flower in the shade, it can probably be grown with only artificial light.

One couple was able to grow Cattleya orchids in their “basement greenhouse” with the help of fluorescent grow lights.

The third “dimension” of light comes into play here. Before now, it didn’t matter much what kind of spectrum the light source gave off.

When a plant gets all the light it needs from an artificial source, the quality of the light is very important. Short blue light waves, which are close to the invisible ultra-violet spectrum, seem to be important for plant growth and flowering.

The longer, red wavelengths, which are close to infrared or invisible heat waves, are also needed, but not as much. The good news is that a lighting system where daylight fluorescent tubes and light fixtures are hung about 10 to 12 inches above the plants can give a very close approximation of natural daylight.

For some reason, the more light you can put on a certain area, the better. Many of the problems that come up when growing plants with artificial lights can be solved by using a fully enclosed growing case and grow tents.

Inside a case or grow tent like this, there would be light, heat, humidity, plant food, and heat. Control can be so well done that graphs showing each factor look like straight lines almost all the time.

It is hard to keep the humidity high enough for good growth in the open basement. On the other hand, it’s not hard to keep the humidity in the closed plant case close to 100%.

What can grow in this situation or on an open bench where the humidity is high?

The tuberous begonia is one of the most interesting subjects. It is a plant that needs a lot of light and does best with long days that can be made with artificial light. The results don’t change much if lights are on all day or if they are on for 16 hours and off for 8.

A friend in Illinois has grown tuberous begonias from seeds to blooming plants and kept the flowers coming nonstop. He has eight separate rooms where he grows many different kinds of plants. African violets and impatiens are two plants that do very well.

Many herbs and vegetables, like peppers and tomatoes, need artificial light to get off to a good start early in the growing season.

Learn More:

• Grill In The Garage: Everything You Should Know
• Turning a Garage into a Man Cave

Artificial light is used to help plants’ reproduction

One of the most important ways that artificial light is used is to help plants reproduce. Once again, the quality of the light comes into play here.

The blue end of the light spectrum is given off by daylight white fluorescent tubes, while the red end of the spectrum is given off by incandescent bulbs.

The visible blue end of the spectrum helps leaves and flowers grow normally, while the visible red end of the spectrum helps roots grow.

Instead of a daylight tube, it’s best to use what is called “soft white” fluorescent tubes to get cuttings to grow roots. These need more light at the red end of the spectrum, which this type of tube can provide. In a closed case or grow tent, the results are out of this world.

Once the cuttings are “stuck” in the soil mix or flats, the lid is closed and doesn’t need to be opened again until the cuttings have grown roots and are ready to be taken out.

A very good way to use artificial light is to force Dutch bulbs without a sunny window. Hyacinths, tulips, and narcissi are put in pots as soon as they arrive, and they are kept in a dark place at 48°F until the shoots are 2–3′′ above the pots.

Treatment with the cold for a long time isn’t needed unless bulbs are being kept back to be forced later. When the shoots reach 3 inches in length, the pots are put under fluorescent lights.

Two 40-watt tubes hung 10 inches above the pots will light up a space that is 12 inches by 48 inches. The temperature should be kept as close as possible to 55° Fahrenheit.

I’ve found that fluorescent tubes are all you need to grow great pot plants when forcing bulbs. But if the flowers are going to be cut, adding a 60-watt incandescent bulb to the two tubes seems to make the plant last longer in water without minerals.

Direct sunlight is replaced or added to these artificial light

Metal halide light

Metal Halide Light is a bright light that stays on for a very long time. To work, they need a ballast kit. During the vegetative growth stage, metal halide fixtures are often used, while high-pressure sodium (HPS) fixtures are used during the flowering stage.

Grow light with high-pressure sodium

High-intensity discharge (HID) lights are what high-pressure sodium (HPS) grow lights are. Their light is in the orange-red range, which is perfect for the flowering stage. Many people who grow cannabis say that high-pressure sodium lights are the best for flowering cannabis plants.

Compact fluorescent grow lights 

CFLs are compact fluorescent plant grow lights. People are using these energy-efficient grow lights for houseplants more and more to start seeds and help plants grow. Even though fluorescent lights aren’t as bright or as efficient as HID lights, they have better color and spectrum, giving the plant more useful light per watt. When many of these lights are used together, they are very effective.

Use the 6500K blue light spectrum 6-12 inches above the plant canopy during the vegetative stage of growth. Use the warm, red 3000k spectrum during the flowering phase.

LED grow lights

LED grow lights, which stand for “light-emitting diode,” are fairly new to the artificial lighting scene indoors. Their main benefits are that they don’t get very hot, are small, last a long time, use less energy, and are very efficient.

One bad thing is that it can be expensive to get light plants to grow well indoors. But expect the price to go down over the next few years as LED lights become more popular.

Frequently asked question

Conclusion

Can plants grow with light from a lamp?

Yes!

It can be a lot of fun to grow plants indoors with the help of artificial light. Most people can get started with a simple setup of two 40-watt tubes hung over a table 10 inches above the plants. Try African violets as your first plant.

Artificial light can help plants grow, but there are many things to think about. Think about where your plants are, how much light they need, and where they are, so you can choose the light that will help them grow the most.