TwinklePhone's Logo Icon Hitting your plants up with the best twinkle from grow lights.


By Austin Lee

Updated on August 26, 2018

What are Grow Lights?

A grow light or plant light is an artificial light source, generally an electric light, designed to stimulate plant growth by emitting a light appropriate for photosynthesis.

Grow Light example
Typical indoor grow light to help grow plants.

How to Use Grow Lights

Light Distance

LED grow lights should be kept at least 12 inches (30 cm) away from plants to prevent leaf burn.

That being said, here are the recommended light distances during each phase of the plant's life cycle:

Stage Light Distance Hours Per Day
Germination 48-56 inches 16-18 hrs
Vegetative 40-48 inches 12-16 hrs
Flowering 24-40 inch 10-12 hrs

Diagram of the recommended distance between grow light and plant.
Too close and you'll burn the plant. Too far and you're wasting electricity.

What color light do I need?

LED grow lights vary in color depending on what plant you want to use it on.

Most plants grow the best when exposed to red and blue light.

That's why you'll see a lot of grow lights with a purple light color.

Purple LED Grow Light
Purple grow lights are more power efficient since they only use energy to generate blue and red light (not green).

(Red + Blue = Purple)

Look for grow lights that have the following nanometer (nm) wavelengths:

  1. Red Light: 620–750 nm

  2. Blue Light: 450–495 nm

So if a grow light product specifies that it shines light in the following wavelengths: 630nm, 660nm, 610nm, 470nm, 460nm, 440nm, you know it's shinning 3 shades of red light (630nm, 660nm, 610nm), and 3 shades of blue light (470nm, 460nm, 440nm).

However, if the light is white, it's still a good grow light because white light contains red, blue, and green light.

That being said, if you use white light, you're technically wasting energy if your plant only needs blue and red light.

This is important if you're looking to save power and money on electricity.


Most think that more light = more growth.

This may work for some plants, but some plants need some time in the dark.

For example, the Mimosa pudica species will wither away when grown for 24/7 under grow lights.

Many plants won't die in permanent light, but it may interfere with their regular growth process.

That's because some plants measure incoming light using photoreceptor proteins.

These proteins utilize light level benchmarks which serve as triggers for life cycle changes (a.k.a photoperiodism).

Plants that rely on photoperiodism for flowering may not be able to complete their life cycle if they live under light 24/7.

A plant in the dark.
Some plants actually need darkness (Can't be under a grow light 24/7).

Grow Light Buying Guide

There are a couple things you should look out for when buying a grow light.

  • The Light Intensity of the color spectrum of the light, making sure it is appropriate for your plant.

  • The Power Consumption of your grow light.

  • The Physical Size of your light.

  • The Type of grow light - COB, T5, etc.? Different types have different features. We will explain all grow light types next.

  • The Cost - Make sure you're getting the best bang for your buck.

Grow Light Types

LED Grow Lights

LED grow lights are made out of light-emitting diodes.

All you have to do is just plug them into an electrical socket and place the above your plants.

LED Grow Light example
LED grow light product example.

Go here to Buy LED Grow Lights.

Power Consumption

T5 Fluorescent Grow Lights

Fluorescent Grow Lights and Compact Fluorescent Grow Lights use substantially less energy than traditional MH and HPS grow lights.

T5 High Ouput (HO) bulbs are the most popular fluorescent bulbs for plant lighting, and they're the most efficient.

Meaning of the "T" in T5

The "T" refers to the diameter of the bulb.

Some examples:

  • T12 has a diameter of 12/8"

  • T18 has a diameter of 8/8"

  • T5 has a diameter of 5/8"

T5 Grow Light example
A T5 Fluorescent grow light.

The more narrow the lamp, the more efficient it will be.

That means T5 fluorescents are more efficient than T8 and T12 fluorescent tubes, because are smaller in diameter.

That's also why the T5 grow lights are the most popular fluorescent grow lights.

Chip on Board Grow Lights (COB)

These are commonly referred to as "COB Grow Lights".

COB Grow Light example
COB Grow light example.

In Conclusion

From farmers to plant hobbyists, grow lights create better results for all types of gardening.

With a grow light, your plant growth won't be dictated by the day-night cycle of the sun.

This means faster plant growth and more efficient growing spaces.

Grow lights are essential for gardeners who are looking to competitively grow plants for a profit - like farmers or marijuana growers.