What Are Grow Lights and How Do They Work?

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By Jeff Hale

Grow lights are an essential part of cultivating indoor plants. They provide a specific type of lighting necessary to produce a successful yield, but what are grow lights, and how do they differ from normal lights?

Grow kit light bulbs are designed to emit wavelengths that replicate natural sunlight. These wavelengths are vital because they offer a specific spectrum of light required for photosynthesis to take place.

Let’s take a look at grow lights, and discuss their features and benefits.

How Do Grow Lights Work?

There are various types of options available, depending on the growing operation and plants you wish to cultivate; however, all grow lights work by providing the proper spectrum of light necessary to promote optimal growth in your plants.

how do grow lights work

HID or high-intensity discharge lighting is often the best choice for large-scale indoor projects due to their high light emittance. In contrast, an LED grow light, and fluorescent light are popular in small, personal grow rooms for their ability to emit a broad light spectrum in a focused space.

Quick Note: Green plants thrive under a grow light because they promote various stages of growth through essential wavelengths.

A full-spectrum grow bulb will offer support to a plant from the vegetative state to the flowering stage. LED lights offer a custom approach to grow lights, with the option of using various lighting hues to produce a specific result.

Choosing the Right Grow Lights

There are essential factors to consider in choosing the best grow lights for your room. The room or location of your indoor garden, the type of plants and their size, and potential areas for lighting are all important when you make a purchase.

How to use grow lights

If your plants and space are small, you can easily install some LED grow bulbs, which require minimal maintenance. If you expect your plants to grow tall and a lot of light is needed, a more robust option with an intense discharge may need to be considered.

If you grow your plants in a living space, such as a closed-off room in your home, you’ll need to invest in a good quality kit with supplies, ventilation, and cooling fixtures, especially for lights like HID that heat quickly.

Adequate space to allow your plants to flourish and flower is also vital; properly spacing your lights helps produce the best results.

Fluorescent Lights

A fluorescent bulb offers an energy-efficient, bright option for you to grow various houseplants, herbs, succulents, and seedlings. Fluorescent tubes also offer a decent spectrum of light for optimal results. Fluorescent lights are affordable and offer a good solution if you’re looking to grow just a few plants indoors.

These bulbs typically do not support large grow projects, so if you’re planning to take on a large project, look at some of the other options on our list.

You should also read: LED vs Fluorescent Lights

LED Lights

led grow lights

You’ll find LEDs a better alternative to fluorescent bulbs due to their fuller spectrum of light and ability to simulate blue light for photosynthesis.

Unlike incandescent bulbs, they produce little heat, so there is no danger of overheating, and plants reach their peak growth without difficulty.

LED lights are more expensive upfront than other grow bulbs; however, they are one of the most energy-efficient options and will save you money in the long term.

LEDs use a fraction of the electricity, and they outlive fluorescent lighting. They are an environmentally friendly option, considering they don’t need to be replaced as often as other grow bulbs, and they require less energy.

High Output LED Lights

This style of LED bulb offers a more intense, full-spectrum light for a wider variety of plants. High output LED lights are a good fit for various plant varieties, including cacti or succulents, citrus plants, and a more comprehensive range of herbs and flowers.

This LED grow bulb offers a higher level of energy savings, with a broader spectrum and more light intensity than traditional LED lights.

HID or High-Intensity Discharge Lighting

HIDs, HPS lights, or metal halide lights are inexpensive and produce a high level of light at full spectrum. You’ll notice excellent, consistent results for every grow project if properly used. They tend to be intense and burn out quicker than LED lights, so they’ll need to be replaced more often as a result.

It’s also important to note that they emit a high heat level, so it’s essential to space them properly not to harm your plants.

You should also read: LED vs HID Grow Lights

Types of Lighting Characteristics

Grow lights utilize electromagnetic wavelengths in order to output a light source that is powerful enough to aid in a plant’s growth.

grow light spectrums

Humans can only detect visible light, whereas plants can detect visible light as well as wavelengths, UV, and far-red spectrums.

Plants use light from the PAR (photosynthetic active radiation) for photosynthesis measuring between 400-700 nanometers. This light energy is then transferred by the plant molecule, chlorophyll, to chemical energy.

Chlorophyll absorbs most light from the red or blue light spectrum, which is found at the peak of the PAR range. The color spectrum of a light bulb can resemble a cool color temperature, such as blue, or a warmer color, such as red.

Different types of grow lights have a smaller to broader spectrum so that all the necessary colors are present throughout the entire cultivation of the plants. For example, UV light helps plants produce the essential natural oils that promote flavor and smell, while LED lights can help promote growth in crops due to their full light spectrum.

What to Know Before you Buy Grow Lights

There are many types of grow lights on the market, and choosing the correct type for your indoor gardening project is essential.

Different styles of artificial light offer different benefits, depending on factors that will determine which indoor grow light will yield the best results for your houseplant.

Consider the following:

Grow Space

How much space you intend to use for growing plants, and do you have enough room for adequate lighting?

Bulb Distance

Is there enough room to adjust the distance between the bulbs and each plant between the germination, vegetative and flowering stages?

Heat Needed

How much heat do your bulbs provide? If you use a grow light that emits a lot of heat like HIDs, ventilation and cooling fixtures may be required.

Initial Cost

Compare the initial cost of the plant light and the long-term benefits. LED bulbs are more expensive upfront. However, they save on energy, money, and last longer. HID lights offer stronger, full-spectrum light, though they cost more initially and require frequent replacement.

In addition to understanding the basics of your growing project, indoor growers must research different brands to choose the best quality for their project. Many brands and price ranges vary, making the task a bit of work to start.

Quick Tip: Once you become familiar with the type of grow bulbs you need, it’s essential to compare reviews and ratings from various places. The overall average rating of a product is your best predictor for a quality product and a good return on your investment.

If you’re unsure of where to start, it’s worthwhile to ask for recommendations from growing experts on the best options for plant growth. For beginners, a start-up kit with all the necessary supplies is a good option.

Ask for Recommendations and Reviews on Lighting Products

If you work for a company or store that sells indoor growing supplies, it’s worthwhile to ask for recommendations on the best options for plant growth. They are experts after all!

For beginners, a start-up kit with all the necessary supplies is a good option. It’s also much easier to begin with the basics and starts with a more minor grow operation to “test” your first kit.

Grow Light Kit Options for Beginners

Starting your first growing project doesn’t have to be difficult or complicated. It’s best to start with a simple set of plants, so you can set up your grow room with all the right equipment.

You’ll find many start-up kits that offer instructions for recommended plants. It’s essential to set up your space as accurately as possible to allow for maximum growth.

Investing in a Grow Light Kit

Grow light kits typically offer the basics, and you may add more supplies as needed, depending on your project. The leading equipment included in a package includes lights, a grow tent, clamps, and fans with filters.

grow light kit

Grow Light

What is a grow light that works best for beginners? If you purchase LED bulbs, your setup will be much easier, as you wouldn’t need to use ballasts to install the lamps.

LED bulbs incorporate the function of ballasts into one unit, so all that is needed is an electrical source to plug them into. They also offer a consistent light source, work with all varieties of plants, and produce a broad spectrum of light.


While not all grow kits include tents, they are usually featured in more expensive systems. The main benefit of grow tents is their ability to control the climate and the environment of the room.

If you do not purchase a kit that includes a tent, some online tutorials and instructions offer DIY grow light methods.


Clamps keep the tent in place while allowing for a protected environment for your plants. Any wiring or additional support for your room should be safely organized so that you can maximize the space. Fans and filters are vital to ensure adequate ventilation and airflow inside the tent, and the grow room.

Preventing Risks

There are some risks involved in creating and maintaining your grow room. Fire is often the first risk that comes to mind. Incorrect wiring creates electrical fires, not overheating from the bulbs directly.

LEDs are cool to the touch and a safer option for homes with pets and kids. CFL or fluorescent lights shatter more quickly than LED or HID lamps, posing a risk.

grow light risks

Keep your grow room electrical outlets as uncomplicated and straightforward as possible to avoid even the slightest risk of damage.

Warning: Overloading outlets and using them for long periods can increase the risk of fire. You’d be surprised at how many people do this!

Mold occurs when the level of moisture in the grow room increases, then fluctuates over time. Turning the lights off frequently can create more mold due to dampness, which can damage plants and pose a risk to your health. Mold and mildew also jeopardize the growing space and may remain after your growing operation.

LED bulbs are the only grow bulbs without mercury, which means there is no health risk from them if they break. Other bulbs contain various levels of this substance and must be handled carefully to avoid breaking.


Grow lights are continuously improving, and manufacturers offer better options for growers at more affordable prices.

Safety and quality are top priorities, and fortunately, there are many products to choose from, whether you are new to indoor cultivation or experienced.

To yield the best results, start small and work your way up. With a little practice, your indoor garden will flourish in no time.