How to Use a Grow Light for Indoor Plants

Cherie Crocker | June 23, 2022

How to Use a Grow Light for Indoor Plants

The grow light industry has sprouted like weeds. Grow lights for indoor plants are now commonly used in greenhouses, urban gardens, and legal marijuana farms. These lights have grown to become a multi-billion-dollar industry. Indoor plants are known to provide many benefits. They help reduce anxiety, improve productivity, enhance healing, and the like. They bring nature indoors and have a positive impact on people's lives. Aside from providing mental benefits, they also add aesthetics. Some even produce consumable products. For indoor plants to flourish, they need hydration, proper nutrients, and grow lights.

A grow light is a light source used to cultivate indoor plants without needing sunlight. The device uses certain wavelength rations in the blue and red spectrums to help plants photosynthesize.

Grow Lights Work Based On the Following:

  • Lamp intensity or Photosynthetic Photon Flux Density (PPFD)
  • Light spectrum or Photosynthetically Active Radiation (PAR)
  • The proximity of plants to the lamp
  • How much natural sunlight the plants are getting
  • How the plants react to the light

Types of Grow Lights

There are two main types of grow lights for indoor use: Fluorescent and LED lights. However, LED lights may be further subdivided into low-power LED lights and high-power LED lights.

Fluorescent Lights

Fluorescent lights are a bit old school, but they are still quite common today. They now share the spotlight with the more modern LEDs. While fluorescents are not as long-lasting as LEDs, they are easy to find in stores and provide a decent option.

Choose T5 HO fluorescent lamps because they produce less heat and are more energy-efficient than older models. Be careful when handling these light fixtures because some ballasts contain mercury. If you have a fluorescent fixture and want to use LEDs, you can find LED lamp replacements with a fluorescent tube design.

Note that the ballast inside the lamp produces heat. Therefore, the section where the ballast is located will be generally hotter. Hence, plants placed under this section may show signs of heat stress. 

LED Lights

LEDs are energy-efficient and will last longer than traditional fluorescent lights. The only downside is the price. If you want to buy better quality lights, you have to be willing to pay extra. Keep in mind that the intensity of the lamps cannot be accurately measured in watts. Reputable manufacturers provide information on the lamp's intensity in terms of μMol/m2/s or micromoles per meter squared per second.

There are different prices for LED lights on the market. The low-power LED lights are more affordable and usually, the first ones you see when searching for LED grow lights. They are good enough for small succulents and other houseplants. However, they are not intense enough for herbs, tomatoes, and citrus plants. Many of these fixtures emit purple and pink light, but you can find broad or full-spectrum white-coloured varieties. 

The high-power LED lights are well-suited for cultivating larger house plants, herbs, and edible plants. These devices have a higher light intensity and will cost more money. However, there are still many low-quality lights out there. Therefore, you must be careful not to fall for cheap quality high-power LEDs. 

Please note that ordinary household lights are not designed for cultivating indoor plants. Incandescent bulbs produce too much heat and are not suitable for growing plants. They also produce heavy yellow and green spectrums of light, which do not support photosynthesis. Halogen lights also produce too much heat and are not energy efficient. 

How To Use Grow Lights

Growing indoor plants is a fun hobby that may soon become a thriving business. If it is your first time using these light fixtures to cultivate herbs or cannabis, you must pass through a trial and error period. Do not be discouraged because everyone has gone through the same phase. Therefore, take your time to experience, learn, experiment, and have fun.  

Here are recommendations on how to use grow lights properly:

Choose Lamps Wisely

Don't just buy lamps without figuring out what to do with them in the first place. Keep in mind that better-quality lamps are more expensive for a reason. You only need to use them for a fraction of the time compared to cheaper alternatives. If you are going to grow seedlings for transplant, get bright lights. However, most houseplants only require low light. Hence, you can buy cheaper grow lamps and put the plants near the window to provide adequate natural light. 

Put the Lights at a Good Distance

It is best to place the lights as close to the plants as possible. The distance varies depending on the lamp, but as a rule of thumb, place it around six inches from the plants. The plants will benefit from the light better when placed close enough. If the lamp is further away, the intensity of the light will decrease. If you use a bank of lights, adjust them as the plants grow. 

Use a Timer

Some plants thrive better when provided with consistent lighting. Remember that many plants are day-length sensitive. Hence, they only need 8 to 10 hours of light per 24 hours. Giving them inconsistent hours of lighting can confuse them.

Determine How Much Light the Plants Need

Foliage plants require somewhere around 14 to 16 hours of light each day. Flowering plants require at least 12 to 16 hours of light per 24 hours. Cannabis requires approximately 18-24 hours of light during its vegetative state but needs only 12 hours of light during the flowering stage. It is essential to give the plants total darkness during the remaining hours. Always turn the lights on and off consistently for the best results. Invest in an automatic timer for ease of use. 

As much as possible, try mimicking the day length where the plants originated. It may not be essential, but it can be for some plants, like basil. Plants from temperate zones usually perceive the month based on how much light they get during the day. Hence, they may start or stop flowering depending on how many hours of light they get. Plants originating from the equator may not respond the same way because they are used to consistent 12 hours of lighting.

Be Sure to Water

Aside from light, plants need a sufficient amount of water for hydration. Most indoor plants need to be watered at least once every one to three weeks. You should monitor your plants and water them when necessary. The frequency will depend on the type of plant you have, its size, rate of growth, etc. For seedlings, make sure that they get evenly moist. Do your research on how much water your plants need, and provide enough hydration.


Always keep your grow lights clean and well-maintained. Remember that indoor gardens are a mix of water and electricity. Hence, it would be best to be careful when cleaning and maintaining indoor light fixtures. 

Are you interested in cultivating plants indoors? Light fixtures are not the only devices you need. Check out Canada Grow Supplies - Grow Kits. We have everything you need to start your indoor growing adventure!

Why Regular Light Bulbs Do Not Work

Regular light bulbs may provide light waves that help plants grow, but they are mostly ineffective. Remember that these bulbs provide sufficient indoor lighting for human use. Hence, they do not usually produce the correct spectrum of light for growing plants. Grow lights are designed with a specific light spectrum, intensity, and colour to help provide maximum energy for plants to flourish. The overall appearance of grow light may look similar to a regular house light, but its effect on plants is different. Remember that our eyes cannot perceive the difference between the lights produced by each kind of light fixture.

How Long Should Grow Lights Be Turned On?

It depends on several factors, such as the kind of light you are using, the environment where your plants are, and what kind of plants you are growing. Grow lights typically come with specific instructions, but there are general practices you can follow. For instance, it is best to turn the grow lights at least eight to ten hours daily. However, some plants may require 16 to 24 hours of light. In this case, it is recommended to use LED lights because they are energy efficient. 

It is best to place the light right above the plant because it mimics the direction of sunlight. Since plants naturally follow the light source, placing it above the plant is the best choice. However, do not place the light too close, this will avoid burning the plants. It would be best if you also used the right intensity of light. If you are growing shade-loving plants, you do not need such strong lights. However, if you agave large plants with big leaves, you may require a more powerful light. Each strain of marijuana comes with its' own preferences.

How to Position Your Grow Light

As mentioned above, it is best to replicate the position of sunlight in nature. Some people place grow lights at the base of the plant. Others even position them under shade lamps, which diminishes the benefit of the light. Although this can help plants get some form of light, it may not be as beneficial. 

Always use grow lights properly. Keep them as close as possible to the plants without burning them and remove any obstructions. Plants tend to lean towards the source of light. Hence, if you want your plants to grow upwards, place your lights right above them to mimic the plants' behaviour in nature.

Optimum Distance Between the Plant and the Light Source

It all depends, if you are growing only one plant, keep the light source as close to it as possible. The recommended distance is about six inches away. However, if you are growing a lot of plants, a couple of feet is suggested for the light to provide as much coverage. Of course, you may need a higher light intensity for this to work. 

The intensity of the light affects the optimum distance of the light source. Generally, the closer the source is to the plant, the more intense its' effects on the plant. However, it also means less coverage. If you are lighting more plants than one, you should consider a bank of lights that can cover the entire area or use a stronger light distanced further away to provide adequate rays to all your plants.

Optimum Color of Light for Growth

Lights come in different colours, and there is a reason for this. Plants require different light waves for various purposes- including leafy growth, flowering, and fruiting. It would be best if you used a white full-spectrum grow light for a full range of light. White light is excellent for supplementing a grow light for plants such as Peace Lilies, Palms Philodendrons, and Fiddle Leaf Figs. 

Red light is commonly recommended for flowering, while blue light is best for vegetative growth. Blue light has similar effects to UVA light and less energy than ultraviolet light. Adding UV light (UVA or UVB) to a grow room is potentially dangerous because UV radiation can damage the plants. 

Related Topic: How to Choose the Best Cannabis Grow Lights

Hydroponic Grow Lights

Hydroponic farms do not use standard soft white lights. They use grow lights because hydroponic plants need to thrive with the right kind of light to produce lush greens. 

Grow lights of hydroponic plants mimic the characteristics of natural light. They are designed to be cooler to the touch to prevent scorching the delicate leaves of the plants and they tend to consume less energy than standard light bulbs. Hence, they can easily support an entire indoor farm with energy efficiency. 

Most hydroponic plants, including lettuce, fall into long-day plants that thrive during the summer season. Hence, they need up to 18 hours of light every day. However, some fall into short-day plants that thrive during the spring. These plants, including cauliflower and strawberries, only need no more than 12 hours of light each day. Others, like eggplant and tomatoes, fall into the day-neutral category. These plants thrive under any lighting condition. Your marijuana plant will require total darkness and tons of light at different times of its' growth.

Why Use a Timer 

Remember that grow lights must be turned on and off consistently for optimum results. Most plants generally need around eight to ten hours of light per day. Others require 16 hours. Therefore, it may be best to invest in an automatic timer to turn the light automatically when necessary.

Unless you are committed to manually turning the light on and off, you need to have an automatic timer. Most timers now come with app control, allowing you to turn the light on and off wherever you are.

Considering Grow Lights for Your Indoor Farm

Growing plants, such as cannabis, indoors provides you complete control of the environment, temperature, humidity, light source, and CO2 levels without worrying about external factors like the weather. Indoor environments typically produce flowers with higher cannabinoid potency. Also, the cost is far less compared to maintaining an outdoor farm. For lighting, here are some recommendations:

1. Kind LED K5 WIFI LED Grow Lights

The K5 series of grow lights are designed to provide your plants with the ideal spectral ratios for indoor cultivation. The K5 WIFI allows you to control the light spectrum and the timing using your smartphone, tablet, or laptop, anywhere you are. With this technology, you can grow quality plants with definite potency. The UV diodes even increase the terpene profiles of cannabis flowers. 

2. Kind LED Grow Lights X Series XD75 Bar Light

The X-series of grow light fixtures are designed to maximize indoor plants' growth, yield, and quality. You can easily connect the fixtures end-to-end to form a stable lighting fixture for your entire facility. These highly versatile fixtures can be used for any lighting application, limited only by your creativity and imagination. You can use the X-series bar lights from propagation to harvest, greenhouse to indoor, and leafy greens to fruit-bearing plants. 

3. Lightstick LED 2' Grow Light Strip

The lightstick strip is designed to keep your garden growing 365 days a year. It is purposely made for hydroponic farms and is considered one of the best options for propagation and nurturing seedlings. You can expect increased performance, improved energy efficiency, and double the lifespan compared to the standard T5 fluorescent light. 

The LED light provides your plants with a consistent 6400k full-spectrum colour temperature and an efficient intensity. With this lighting system, you can expect your yield to improve dramatically. Plug it in when you start growing. 

Last Words

Growing plants indoors is a fun hobby that can lead to a thriving business. However, it is always recommended to use the right grow lights for your indoor plants. A quick tip to remember is: grow lights mimic the qualities of natural light and should be adequately positioned to allow maximum plant growth.