Growing Tomatoes With Artificial Light in 2023 – Expert’s Advice

by Lee Safin

As an experienced gardener, you must be familiar with the concept of growing plants indoors in an artificially sustained environment.

For those of us still new, it is possible to adjust light, ventilation, and the temperature of a room and grow various types of plants. With proper setup, you can grow off-season fruits, vegetables, and flowers.

We will discuss growing tomatoes with artificial light in this article but after going through this article, you will even be able to grow a plant in your basement flower pot. Ideally, you can also use a grow tent for much precision.

Naturally, a plant grows by being exposed to the atmosphere. It receives sunlight for a certain period (during the day), there’s carbon dioxide in the air and an occasional light breeze. All these factors, in a synchronized manner, help a plant to grow.

Growing Tomatoes With Artificial Light in 2023 – Expert’s Advice
Growing Tomatoes With Artificial Light in 2023 – Expert’s Advice

Growing Tomatoes With Artificial Light

The first and most important rule is to know every detail of the plant you will grow, including from seeding to the final stages of harvest.

If your plant is suitable to your region’s natural climate, you can allocate them space with proper soil. Suppose you want to grow potted plants in rooms that receive no sunlight like your basement. In that case, you need to adjust the light in your room to substitute for the sunlight and ensure suitable ventilation to circulate carbon dioxide and oxygen properly.

If you are growing an off-season plant or a different climate, you need a grow tent or a properly insulated room. To set up the ideal atmosphere in your room or grow tent, you will need a suitable ventilation system, lights, and an air conditioner if your plants require a drop in temperature.

A Good Understanding of Light and Its Effect on Plants

While setting up your light system, you need to consider various other factors like light spectrum, light intensity, and the duration of the light. Together, these factors will affect your surrounding temperature, how your plants grow up to be, and the end harvest.

Therefore before purchasing a grow light, you should know the light requirements of your plants in terms of:

  • Light Spectrum (Color Hue)
  • Light Intensity (The brightness)
  • Duration (how long should your plants be exposed to light)

What is Light Spectrum?

Various wavelengths of colour merge to form white light. These wavelengths of colours are called a light spectrum. There are seven light spectrums or colours. Sunlight consists of a full range of light that is all seven colours of the rainbow.

The intensity or brightness of the sun changes throughout the season. It slightly alters the wavelengths and also the natural temperature. This, combined with soil and water, is one reason why individual plants do not grow in some climates.

However, there are specific recommendations of wavelength or light spectrum during certain phases of the plant.

During growth and foliage, most plants require a blue spectrum or blue light. At the same time, flowering and fruiting, most plants will need red spectrum or red light. However, these recommendations are subjected to argument because different plants have different requirements; as I said, know your plant better.


Since I mentioned that the most suitable spectrum is the blue and red colour during different plant growth stages, it does not necessarily mean that you purchase and set up red and blue lights specifically during various plant growth stages.

Plants require all the seven colours present in white light; only during certain stages is it recommended to adjust the light’s hue or shade so that specific spectrums like red or blue will be intensified or more dominant. Think of the red colour to be more like sunset or sunrise and the blue colour as crystal clear sky.

These days, mid-range grow lights come with options that help the user customize the hue or colour temperature.

What is Kelvin?

Kelvin is the unit that is used to measure the colour temperature of white light. It determines the visual coolness or warmth of the light. The unit is used as the higher the degree of Kelvin is, the cooler the light is, which means that the light is more towards blue color. When Kelvin’s degree is high, it means that the light is warm, indicating more red light. The kelvin requirement for house plants ranges from 4000 to 6000 kelvin.

What is Light Intensity?

The intensity of light refers to the brightness of the light. The intensity of light is independent of its spectrum, wavelength, or color. So very bright lights mean that the light intensity is very high, whereas low light intensity indicates that the light is dull or bright.

By nature, light intensity differs as the brightness of the sunlight changes from morning to afternoon.

Different plants have different levels of light intensity. You can quickly look up the required light intensity for the plant that you are going to grow. In case you have had a hybrid plant or uncertain about your plant’s light requirement, you can observe the leaves.

Plants that require low light intensity will generally have light-coloured leaves, which are usually long and thin. On the other hand, plants with dark green leaves and short branches tend to require bright light or high light intensity.

I categorize plants into three categories of based on their intensity of light requirement; low light intensity (low light), medium light intensity (medium-light), and high light intensity (bright light). Categorizing your plants based on their intensity of light required will help you to select the right type of light.


High light intensity or bright light will increase photosynthesis. Plants or stages in the growth that require a lot of photosynthesis will need luminous or high-intensity light.

Light intensity also decreases as the source of the light moves further away from the plant.

How Long Should the Light Duration be?

We all know that light helps plants to produce their food through photosynthesis. However, keeping your plants in light throughout the day will damage the plant.

Plants rest during the night. Like adding lights for artificial sunlight, you too need to create the illusion of night by switching off these lights from time to time. This will give your plants time to rest and respire.

Like I always emphasize on knowing your plant, different plants will be requiring different light duration. Even different stages of plant life will require a different duration of light.

Judging on the duration of light required, you can divide your plants into three categories; short-day plants, long-day plants, and neutral plants.

Short day plants

These are mostly plants that grow during winter or when the days are shorter. Generally, these plants require less than 12 hours of light. Some examples of short-day plants are rice, soybean, and onion.

Long day plants

As the name suggests, these are plants that require more than 12 hours of sunlight. Usually, they require 15 to 18 hours of light a day. These plants generally grow in summer or in places that have long days. Some examples of long-day plants are cabbage, wheat, and radish.

Neutral Plants

These are plants that grow and flower regardless of the duration of light or sunlight received. Neutral plants can be kept in light from anywhere between 8 hours a day to 12 hours a day. Some examples of neutral plants are tomato, peas, and rose. Bohobar Restaurant is very popular for serving neutral plants like tomatoes in Australia.


If you are going for a perfect approach, a photometer is an instrument that will help you measure the light spectrum.

To measure the intensity of light, you will need an instrument called a light meter or illuminance.

Types of Artificial light

Now the market is littered with various kinds of grow lights, all of the different kinds, and it can be quite overwhelming when deciding your first grow lights. You will find many commercial grow lights options but remember that each light has its specific uses.

Below I have highlighted some major types of grow lights. This will help you know how each type of light functions. Identify your need and decide the most suitable type of grow light.

Fluorescent lights

These lights are your usual tube or rod lights that you use daily in your house. These light tubes can fit in most regular light sockets. So a setup with fluorescent lights is straightforward and easy to assemble.

Fluorescent lights consume 75% less electricity when compared to incandescent lights. For example, a 100 watt fluorescent light will consume the same amount of electricity as a 25-watt incandescent bulb. This makes this light setup the most economical.

These lights are ideal for plants that require medium light. Fluorescent lights also produce less heat.


Generic fluorescent tubes provide cool light, which means that these lights have a higher concentration of blue wavelength. Keeping this in mind, you should be looking for white fluorescent lights if you want a full spectrum of wavelengths.

LED Lights

Grow lights are generally Led lights. These lights are like fluorescent lights, energy-efficient, and economical in the long run. These bulbs also emit more light and generate less heat.

Since Led lights are most commonly used in growing plants, the setup for these lights come in various options. You can easily purchase stand-alone, desktop fixtures, and even clip-on support to set up Led lights.

Led lights are more customizable, so you can tune into a specific spectrum that is needed for your plants. You can adjust it to emit more red or blue spectrum wavelength during a particular stage of growth. They can even be programmed to emit different light intensities or brightness during different times of the day.

You can also keep upgrading your Led light setup to install smart technology that can be synchronized to your smartphone. You can set in timers and so that the light intensity (brightness) and light spectrum (colour hue) is automatically adjusted to your custom setup during various time of the day.

Incandescent Lights

This is a more old technology of light bulbs. People from the 90s will remember using these bulbs in their homes with screw-in holders. These lights can be very tricky to make good use of. The energy or electricity consumption of these bulbs is also very high.

These lights produce a lot of heat. 90% of the energy consumed is converted to heat, and the remaining 10% is used for light energy, so it is very advisable always to keep this light far away from the plants.

There are some plants like dracaenas, ivy, snake plant, etc., that require low light. You can place these house plants near an incandescent light. Since they require low light, you will be using a bulb with low watts that will emit enough light and generate the necessary heat required.

Always remember to place the plant far away from the light source. Keeping your plant too near will cook it because a major portion of its heat consumption is converted to heat energy.

Halogen Lights

These lights are similar to incandescent lights.

They generate a lot of heat and is one of the trickiest to use in growing plants.

These lights are also very unsuitable for growing plants, but their lighting is more inclined towards the red spectrum, and you can use this to your advantage.

The Most Suitable Light Type To Grow Tomatoes Indoor

Judging by the benefits these lights provide, it is evident that the best is the Led light system and the Fluorescent lights.

When given a choice between the two, I think that Led lights are much better since they provide a huge customization option that can be easily adjusted to suit different kinds of plants during different growth stages.

Led lights are the most expensive kind of lights when purchasing. If you have a tight budget, you can opt for something else; however, LED lights are much more economical in the long run as they consume much less electricity than fluorescent lights.

The life span of Led lights is also very high. In terms of safety hazards, fluorescent lights are usually in tube form and, when they break, has a chance of shattering glass all around. Led lights, on the other hand, provide much more safety.

What Power Light Do You Need?

We know that light bulbs are measured with watt. For those confused, watt is the unit of power.

You purchase light bulbs based on the watt. The higher the watt of a bulb means, the brighter the bulb will be or intensity.

When deciding what watt bulb to buy, I suggest you go for a little higher than you need, like say you need 32 watts, go for 50 watts because you can always adjust the distance between the light source and your plants to get the most desirable light intensity.

However, if your watt is low and needs to increase the light intensity or brightness at certain stages of growth, it won’t be easy.

Determining The Area of Light Coverage

It can be very confusing to determine the exact area a light bulb will cover. As a thumb rule, you can safely assume that a 40-watt bulb will cover an area of 1 foot by 1 foot.

To determine how much area you will be used for growing your plants and getting light of the required power.

So suppose you have a large grow tent, or a grow room with dimensions 6 feet by 6 feet. You can choose to purchase a 240-watt bulb directly or six blubs of 40watt each.

If you purchase a 240 watts bulb, remember that this bulb is also brighter of has more light intensity.

If you want to reduce the light intensity, you can take the light source further away from your plants. If you opt for the six bulbs, divide your total space evenly and place the bulbs accordingly.

You can also find grow lights directly in the market, which will be labelled with all the information required, including the coverage area.

However, these grow lights, although the most suitable, can be very expensive.

How to Hang Grow Lights

No, the most suitable place to hang your lights is right above your plants, as this will help to mimic the sun’s behaviour further. Additionally, you can directly purchase grow lights that you can quickly assemble.

However, for those of us looking for a more custom and cost-efficient approach, you can directly purchase Led lights or fluorescent bulbs along with the right socket for these lights in any hardware store. Also, purchase PVC pipes of suitable diameter along with corner and tree section fitting.

Now you can easily construct a frame of your own choice with the PVC pipes. Attach the sockets along with the bulbs in the necessary places.

Now when hanging the frame of your lights, use rope ratchets, and construct a pulley system to adjust the height of the light from the plants at will.

Wrapping up

Now you are ready for growing tomatoes with artificial lights indoors.

Before you purchase a grow light, determine the light intensity and light spectrum of your plants. Remember, it will vary at different stages of growth.

Also, keep in mind the duration of light received by your plants.

Know the different types of light and how they function. If funds are not a problem, then go for led grow lights or horticulture lights. However, you can always come up with a custom approach to your needs.

You will find many types of lights on the market. If you are using any light bulb which produces heat, keep it far away from your plant.

Too much heat will cook your plants, and also, do not forget to ventilate your grow space.

About Lee Safin

Lee Safin was born near Sacramento, California on a prune growing farm. His parents were immigrants from Russia who had fled the Bolshevik Revolution. They were determined to give their children a better life than they had known. Education was the key for Lee and his siblings, so they could make their own way in the world. Lee attended five universities, where he studied plant sciences and soil technologies. He also has many years of experience in the U.S. Department of Agriculture as a commercial fertilizer formulator.

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