How to Use Grow Lights for Indoor Plants

How to use grow lights for indoor plants is a common yet important question. The indoor gardeners at the beginning, keep on asking this question. Before we get ourselves into the loophole breakers, let’s know what the grow light is.

The grow light is the system of providing artificial light to the plants. Now, you might be wondering why do you even need this.

Let me tell you one thing.

In this guide, the beginners will find everything they need. From the types of the grow light to the use of it, everything will be discussed here.

Mother nature is divine and shows us her charisma every now and then. However, the desired plants you are planning to grow in the field or in front of the house need a large spectrum of sunlight.

Grow light offers many benefits for indoor planting. In lack of sun, the indoor gardener can see the growth of their favorite plants in front of them.

Without a southern side window, getting enough light is not possible. Not to mention, if you have a greenhouse, it will also help the plants to grow.

However, the greenhouse and a window might not be everyone’s cup of tea. But the plants do beg for more sunlight.

To help you, the grow lights for indoor plants are ready. This guide is dedicated for the beginners and the guide includes-

  • Types of grow light
  • How to use and install the grow lights
  • Frequently asked questions
  • Facts you should know

How Does the Grow Light Work

The grow light helps by mimicking sunlight and in the presence of sunlight, the plants start photosynthesis. In the photosynthesis period, the plants use photons from the grow light.

Also, the plants produce energy and food for themselves. When the sun does not provide the photons, plants lack the food and nutrients. To help the plants to survive in such surroundings, the grow light helps the plants to produce food.

Stages and Type of Essential Light

Seedling Stage

However, the seedling stage of indoor plants needs lesser exposure to LED light. Because this is a complicated stage where the spores are formed. When the plants will get maturity and strength to prevent diseases and calamities, the exposure of light should be increased in a decent manner.

Seedling stage requires blue light and the range is 400-500 nanometer. This range is perfect for the indoor plants seedling stage.

Vegetative Stage

Since the vegetative stage is one of the most important stages, the gardener has to take extra care of the plant. The vegetative stage determines a healthy reproduction stage.

Vegetative Stage

For this stage, metal halide lights are perfect. Why do I consider this grow light perfect for vegetative stage?

I have plenty of reasons for this and the most important one is the light emission rate. Metal halide emits larger spectrum blue and UV radiation. In vegetative and reproductive growth stages demand larger light or full-spectrum light.

For this specific stage, HPS AKA high-pressure sodium lights are useful, as well. Full spectrum light is necessary for other cycles of plants.

How about the red spectrum?

The red spectrum influences the flowering stage of the plants and triggers this stage to produce essential flowers. Red spectrum light ensures the flowering does not let the plant energy go in vain.

How can you speed up the vegetative stage?

Gardeners are conscious about speeding up the vegetative stage. So, if you want the same as other gardeners you must have to think about the spectrum of light.

Red spectrum light works well but the High-pressure sodium is the perfect option for speeding up the vegatative stage.

LED is another charisma in the grow light market because you can get the specific wavelength light if you order. Not only the people of earth are using it, but also, NASA has successfully tested the efficiency of LED grow light.

Flowering Stage

Flowering stage of a plant is the reproduction period when the plant needs the most attention. After the change of vegetative stage, the plant enters the flowering stage. Also, this stage needs the attention of grow light the most.

The yellow spectrum of light is needed at this stage and the perfect range is 570nm to 590nm.

Types of Grow Light

The grow lights are of many types but all of them belong to the basic types. Since they have several types, their functions are different.

Grow lights are important for horticulture, indoor gardening, hydroponics, aquatic plants, food production and what not. Importantly, it plays a fantastic role in the industrial sector. For the indoor gardeners, this artificial light has come as a blessing.

Knowing the importance and use of grow lights is as important as to know the types of it. Grow lights are usable in both household and industrial purposes.

Have you heard of the inverse-square law of lights?

The inverse-square rule says- “The point of light source’s intensity that approaches the surface becomes inversely proportional to the square of the distance of the surface from that source.”

Why did I mention this law?

The law has made things clear to us about the distance’s relation with the grow light. This is the reason to build types of efficient grow lights for many stages of plants. Their usage is unique based on the necessity and use.

You are about to find the reflectors which are implemented to enhance the light’s efficiency. The grow lights have to be set properly because the intensity of it impacts the critical yet important mechanisms of plants.

Before setting the light on the plants, you must remember the spreading of the lights.

Let’s check out the important types.

The grow lights have several ranges-

  • Incandescents
  • Fluorescent lights
  • High-intensity discharge lamps (HID)
  • HPS
  • Light-emitting diodes (LED)

Mostly, fluorescent light has been providing an excellent service to help the growth of plants. However, the HID is not less useful in professional use. Not to mention! The high-pressure sodium and metal halide lights are the ancient ones.

The indoor gardeners are not preferring these lights. Guess what? Fluorescent is taking over metal halides because of the outcome fluorescent is providing is far better than metal halides.

You definitely know the plant cycles require several nutrients and the stages of producing nutrients occur either in the optimum photoperiod. The light or dark period influences the life cycle of the plants.

Also, you will find a number of grow lights in the market but not each of them are of your need. Let’s check the basic types of grow lights that a beginner should know.

Incandescent Grow Light

This Incandescents grow light is one type of grow light and they were used in ancient times. The reason behind not using it modern time are-

  • Low efficiency
  • Needs more light
  • Provides less output
  • Consumes electricity and power

How to use Incandescent Grow Lights

You have to place the light 24 inches over the houseplants you want to grow. Since it provides 90% heat and 10%, it might burn the plants out of extreme heat production.

Fluorescent grow lights

Fluorescent grow lights are spiral or small shaped and they have achieved more popularity than incandescent lights. And their range is 2700 K to 10,000 K and these lights are of two types-

  • Compact
  • Tube-style

How to use Fluorescent Grow Lights

  • Remove the ballast cover
  • Cut the wires with the leading ballast to ensure the electric flow runs neutrally
  • Remove the ballast from the frame
  • Check if the sockets are shunted or non-shunted. We need non-shunted wires for security.
  • You have to strip the wires and here the white is neutral, black is the opposite.
  • Put the wires through the tombstones
  • Place the ballast back at its position
  • Setup the fluorescent grow lights

Place the grow light within 24 inches to get productive result

High Intensity discharge Grow light

High Intensity discharge/ HID grow light has won the popularity of grow light because of the light intensity. It features the high lumen-per-watt proficiency that helps the life cycle.

HID lights have many types of lights and they are-

  • Metal halide
  • High pressure sodium
  • Mercury vapor
  • Conversion bulbs

The range of HID ratings –

  • 150W
  • 250W
  • 400W
  • 600W
  • 1000W

HID is a broad spectrum light and the penetration of this light is far way stronger than others. Consumption of electricity is amazingly efficient and so, it does not come at a cheap rate. These lights are expensive and demand specific light fixtures.

On the other side, this light provides huge warmth for the users. Plants like tomatoes or lemons need more heat than other plants. So, use these lights if you are planning to have the favorite tomatoes and fresh lemon juice.

High Pressure Sodium(HPS)

High Pressure Sodium

HPS lights are a better option than fluorescent grow lights as they are one half of high density discharge. These lights are perfect for you if you have used incandescent for a long time. Because they consume less energy than others. It’s a type of HID grow lights and their installation process is the same.

How to Use HPS and HID Grow Lights

  • Place the HPS grow light above the plants at a safe distance
  • For the HPS grow light, get a cool tube because the wings of HPS lights become extremely hot. The cool tube will keep the environment safer for you.
  • While placing the grow lights, you must do the test to know the heat is perfect. Place the hands on the light(switch on). If the heat is not bearable, it needs some changes because the leaves might get burnt.

Check the table and get the idea of how close or far you should place the lights

Grow Light Closest Furthest Sunlight
150W 8”(20cm) 12”(30cm) 10”(25cm)
250W 10”(25cm) 14”(35cm) 12”(30cm)
400W 12”(30cm) 19”(48cm) 14”(35cm)
600W 14”(35cm) 25”(64cm) 16”(41cm)
1000W 16”(41cm) 31”(79cm) 22”(55cm)

Also, don’t forget to check the instructions of the HPS grow light and don’t place them less than 12 inches.

Light Emitting Diodes (LEDs) Grow Light

LED grow light is another type of grow light and they are less expensive than HID lights. Consider these lights your friend as they do not consume much electricity and do not waste it. However, the light has a complete dedication to the development of indoor plants.

Do not purchase the usual LED lights from the nearby grocery stores. Those lights are not for indoor plants and the grow lights are smarter than those.

The LED grow lights are technologically well-developed and the light emission capacity is incredible in them. Try to purchase the best highest yielding led grow light for indoor plants from the horticulture suppliers.

What are the advantages of this light?

LED lights provide great intensity and they support while requiring a full-spectrum thing. Also, the light shows more intensity per square foot and produces less heat.

How To Use LED Grow Light

You have to maintain several steps to use LED grow lights. So, check the steps before you jump to install them.

Step 1

  • Place the lights properly at a safe height over the plants
  • In the flowering stage, the grow lights height has to be 300-600mm. And this is the minimum requirement of the flowering stage. The standard distance is 400mm above the plants.
  • When the plants are in vegetative stage, the distance will be the same – 300-600mm. If the plants have many leaves, the placement of grow light will be lower for better penetration light.
  • Early vegetative stage requires more exposure to the light and so, the light set up has to be above 300mm above the plants.

Step 2

  •  It is an assumption of the indoor gardener that they need to water the plants. This creates a confusion for the indoor gardeners, especially the beginners.
  • Since no evaporation occurs under the LED light unlike HPS, the watering is not much of a necessity.

Step 3

  • The plants need nutrition and an abundance of nutrients can kill the plants.
  • As the plants are growing under LED light, providing Cal-Mag during the growth is must.
  • In case of hydroponic systems, top less nutrients as the evaporation is reduced.

The Myth about Watts of LED grow lights

Watt Tells You the Brightness Effect

Watt is a unit and it is used to measure the lightening or brightening capacity of a bulb whether it is an incandescent or fluorescent light. A bulb with 100watt provides a better brightening effect than a 20 watts bulb.

To be honest, the LED light is quite the opposite of the mentioned feature. Whenever you see the watts in the LED light packaging, simply consider it as the consumption of electricity.

It will determine the charge of electricity and the watt does not entirely inform the users about the exact brightness the grow light is about to provide.

Photosynthetic Photon Flux Density VS Watts Per Area Rule

When you have to set up the LED light for seedlings, the manufacturer will inform you of a simple rule. But the rule is not everything because the brightness effect does not complete the grow light duty.

The photosynthetic photon flux density is the most important element for completing the photosynthesis mechanism in plants. Since watts do not refer to the gardeners about the wavelength, no point to rely on the simple rule mentioned by manufacturers.

LED Grow Lights Do Not Produce Heat

People think LED lights cannot produce heat but this is another myth. Research on LED lights says it can convert more than 20% heat.

Since LED lights are pretty famous and provide a great service to the users, they are more efficient one. This is not entirely true and the light does not use the full electricity.

High Watt Begets Better Result

We think the more watt bulb we purchase, the result will be durable with fantastic services. LED bulbs of 1,3,5,10 watt and these are the mainstream ones.

Tell me the difference between 3 and 5 watt bulbs. Can you?

Well, I think I can guess the answer. This 5 watt bulb is better than 3 watt bulb because it will provide a brighter effect and better service.

I am sorry to say this thought is not appropriate because the watt does not express the brightness of a light. Maybe the development of a 5 watt bulb costs more than 3 watt ones. But the service is the same.

As you know, we are on the verge of a new era where technology rules over us. The high watt bulb accepts new technology which has led to the increased amount of cost.

Otherwise, the low cost bulbs are completely fine and the service of 3 watt grow light is equal to the 5 watt bulb in a wide extent. But you decide which one is preferable for your indoor gardening.

The Grow Light has everything the Sunlight owns

Well, as you are smart to guess what I mean to say, I will not explain this myth in detail. Several companies are in the market and they are accepting the false marketing policy saying ‘get the sunlight at your place’.

The sunlight does not only have a red and blue range of photons, it has yellow, green, etc. No plants do not use them!

So,the grow light is doing many things but mimicking the sunlight is not one of them. Before you make a purchase, I will suggest you not to believe in those companies.

LED Grow Lights Are Not Harmful For Plants

Did you see the burnt leaves? These leaves look different from being burnt by the sun ray. Not to mention, the leaves are not eligible to take as much sunlight as they receive from nature.

So, the myth about LED light should not continue preaching as it is not the true fact. If the light provides 800 PPFD, some plants will die out of dehydration.

The body mechanism of plants is similar to human beings. None of them like to have extra! Did you understand the bottom line?

Well, the bottom line is you should not turn on the LED grow light for 24 hours. Give the plants a healthy break to maintain their physiological balance.

Specifications on Coverage Area are real

The gardeners keep on asking one question to the manufacturers ‘how much area can the light cover?’ To keep the prestige up, they do not explain the whole thing. Mostly, they say the grow light will cover 8ft or 10ft.

This area specification is nothing but a joke. Whenever you are hanging the light upward, you will see the light is covering more space than the manufacturer mentioned above.

The light shape matters a lot!

If the grow light’s shape is a circle, it will not cover more area than your expectation. But when the light shape is rectangle, you will see how much space it covers. The rectangle shape is prone to cover more area because of the shape.

Plants Don’t Need Green light Spectrum

Since the green leaves reflect the green light, we have the assumption that they do not need this light spectrum. It is incorrect information.

Warm or Cool: Which One is Perfect?

As a beginner, you must know the basics of the grow light. And one of the important factors is to understand the color spectrum because it is the hidden influence.

The grow lights have labels printed on the packet like 2700K or 4000K. This explains how much warmth or coolness this can provide. As much the light spectrum increases, it provides a cool impact. The lesser the spectrum, the hotter the color is.

Now, you might be wondering ‘which one is the best option?’

There is no best or better since both of the color spectrum is equally important. Based on the cycles of plant and demand of the photons, electrons determine the necessity of them.

When you are about to use the lights for foliage growth, 2700K light will not be enough. They need more intensity of cooler light. So, use of 2700K light will destroy the foliage and the perfect range is 6500k.

However, there are other plants, flowers or fruits that need warm light to germinate, foliage or other mechanisms. If the plant needs to produce seedlings, vegetables, crops, you will need cooler spectrum lights.

On the other side of the coin, marijuana, flowers, lemon, peepers, tomatoes, cucumbers  need warm bulbs. So, decide the type of light you need to grow the indoor plants.

How to Use Grow Lights for Indoor Plants (Installing)

Since you know about the types and basics of them, you should move on to the installation process.

You buy the grow lights and plants to nurture them for the first time. But you have no clue about the installation process.

How does it sound? ODD!

Though the installation process is not rigid, I can show you the simple yet elementary steps that you need to follow for every grow light.

Nothing to worry!

Let’s follow the flow!

Determine Quantity of Bulb

First, you have to determine how many bulbs are necessary for your gardening and plants. The edible plants flourish in 30 watts per square foot. So, if you are growing the species of spinach, you need to have minimum 30 watts bulbs.

However, the fruiting plants like tomatoes or other plants do not grow in this limited wattage. These fruiting plants need 40 to 50 watts for every square foot.

How to calculate the grow light quantity

To calculate the grow light quantity, you have to multiply the number of watts with the square footage. Then, divide the number of watts number which is necessary to use.

Place the Light Rack

Since the lights have to be hung in a place, having the light rack is a bliss. The lights have to be at a safer distance from the plants. These plants are growing and the light intensity will gradually change based on the necessity.

What kind of rack should you buy?

The light rack needs to have a pulley to fix at the right place whenever you need. To achieve this, you need to have one type of pulley system. Also, the metal chain light fixtures are the best options for changing it.

The metal chain system is better than the pulley one. Get one from the online or offline shop.

Ensure Proper Exposure to Light

The darkness and light are equally important for the plants. Since grow light is the substitute of sunlight, the plants perform the photosynthesis in the presence of these lights.

From photosynthesis, the plants produce their food and the byproduct is oxygen. In the darkness, they have some other sort of mechanism to provide energy for producing flowers and fruits. Also, these mechanisms produce energy for survival.

If the grow lights produce heat more than 80 degrees, you do need to install a ventilation system. Otherwise, excessive heat generation will cause harm to the plant’s regular mechanisms.

How Close Should Grow Lights be to Planted

The grow light has to be placed in a certain distance from where the plants won’t get burnt. Sometimes, the heat production of light causes severe damage to the plants and they can’t complete their mechanisms and cycles.

Mainly, the grow lights are placed between 12 to 30inches distant from the plants but it might vary based on requirements.

Frequently Asked Question

How many hours a day should you use a grow light?

The grow light has to be used as a wise gardener and you can use these lights 14 to 18 hours a day. This photoperiod is not the same for all sorts of plants. Importantly, the photoperiod depends on the plant type.

Based on the plant physiological demand, the dark and photoperiod are chosen. Since you know there are tons of myths about grow lights, you must be careful while using them. Certainly, you do not want to destroy the desired garden.

Can you leave grow lights on 24 hours a day?

This is a phenomenal question asked by the strategic indoor gardeners. However, the straightforward answer is no, you cannot leave the grow lights on 24hours a day. The answer is not unknown to us but let’s check the vital points out.

Photoperiod and dark period are equally necessary for the plants. In a photoperiod session, plants use the light to convert the food into their food.

You must provide 14 hours to 18 hours lights for indoor plants. They have complicated and intense mechanisms and the mechanisms require photons.

In addition, do not turn the grow lights on for 24hours because it will hamper their growth along with prohibiting nutritions to pass properly.

Can any LED light be used as a grow light?

LED lights are of many types and using any of them as a grow light is nothing but a bad decision. Not every LED light can act as a grow light.

The reason is pretty common to guess. As the LED light has accepted the new benefits for plants, you will never like to have the classic and boringLED lights.

To be honest, the grow light is a high-technology based element to develop the indoor planting process, you cannot compare it with usual ones. Whenever you are using these lights, you have to be careful about the features of them.

These lights do not have one single light, the lights are compiled with a wide spectrum. But you can use the white LED one as a grow light, this light has a wide spectrum to help the growth of indoor plants.

What type of light is best for growing plants indoors?

The answer of this question is a little bit tricky and not easy to answer in a few words. Based on the type of your plant, the type of light should be chosen. Also, it depends on the shape and light capacity of the grow light you choose.

Not only these, this color of the light is another important factor to consider. Before you purchase the grow light, look for the requirements your plants have.

How much time the plants need darkness?

The indoor plants require  4 to 6 hours darkness for the cycles they run during night in nature. So, give them the spared time to utilize in darkness.

When the plants are outside of your place, they have nature to heal, support and nurture them. Though indoor gardeners are conscious enough to have the best production and nurture in the same way. However, if you are an indoor gardening lover, this question must have risen in your mind.

Should I turn off the grow light at night?

Based on the photoperiod your plant needs, turn off the grow light. It does not matter whether it is night or day if your surroundings cannot afford proper sunlight.

When you are planning for growing indoor plants, it is an utmost important task to check the requirements. If you do not know their life cycle, physiological and chemical things, you will lose the plants near soon.

One of the important factors is to keep the plants alive is the photoperiod. So, know the grow light requirements the plants have and do not leave the light turned on for 24 hours.

Can Too Much Light kill a plant?

Not only too much light, too much hydration can kill a plant as well. If the light exposure is too much for the plants, it will burn the leaves and do not support the growth.

Gradually, the fruiting and flowering capacity will get destroyed and you will feel demotivated. Consequently, the plants will die in lack of proper dark period and physiological disturbance.

What color light is best for plant growth?

The plant growth needs a huge spectrum of light. From blue to red, every spectrum of light is important for the growth of a plant. So, there is no specific color for plant growth.

Facts You Should Know

Buying the best grow light for indoor plant is tough for a beginner. But you do not have to worry much. I have come up with the important factors to check before purchasing.

Watt Range

People think of different perspectives and they think more watt bulbs will provide more efficiency. But the lights will run out if you use more than 1000 watts.

However, the bulbs with 600 watts are better for foliage nurturing. Also, these lights do not run out within a month or so, providing fantastic service to help plant’s growth.

Select the right bulb

You will find two types of bulbs in the market and they are-

  • MH
  • HPS

MH is specifically important for the vegetative stage of plants. In the vegetative stage, you will find it more efficient because the blue ray of this bulb is vital for plants.

On the other hand, HPS bulbs are great for normal status of the plants. After the vegetative stage, you have to replace MH with HPS for maintaining the physiology of plants.

If you are running out of budget, purchase HPS bulbs as MH bulbs are more expensive. Good deal!

Single VS Double-ended

How to use grow lights for indoor plants have allowed the gardeners to get to know about the  types of bulbs. Now, you must consider the difference between single or double-ended bulbs.

Double-ended bulbs are better than single-ended ones. But the double-ended bulbs are expensive and the single-ended ones are fantastic for the indoor gardeners.

To be honest, the double-ended or single-ended bulbs need a cooler. It will enhance the productivity of the bulbs.

Distance of Grow light

Hanging the grow light at a perfect distance is an important task to complete properly. Now, the grow light has its benefits if you can use it with proper optimization.

Based on the grow light watts, the distance of light has to be maintained. Let’s check the parameters for the types of lights –

  • Fluorescent Grow Light: 3 to 12 inches
  • LED Grow Light: 12 to 24 inches
  • HID Grow Light: 24 to 60 inches


Nurturing plants in a place where sunlight is rare is tricky. Plants are demanding and they need proper care to survive.

If you are a grow light user and trying to nurture some species, these lights are going to be the game changer. Sunlight is not an achievable environment where the people cannot go out in the winter season.

I am asking you to read the whole guide because each corner has vital information for the beginners. Many plants are in the bay of nature which need 18 hours of sunlight. So, the plants beg for the abundance of sunlight which can be avail by indoor plants.

How to use grow lights for indoor plants does not only include the straight answer, it has many more to explain.

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