Best Grow Lights for Indoor Plants: Comprehensive Guide to Lighting, Fixtures, and Timers
Updated 1/24/25 by Angela Rogers
Thinking about starting your first indoor grow? It's easier than you may think.
In this guide on grow lighting for indoor plants, we'll consider the different types of bulbs available and their respective benefits. Additionally, we'll consider fixture and reflector types before moving to peripherals, including ballasts, timers, and controllers.
Color Temperature and the Plant Life Cycle
Most plants go through a growth (also known as "vegetative") stage and a flowering (also known as "budding") stage. Each stage thrives under a different part of the light spectrum, represented by color temperature.
Lights with a color temperature of 5000 Kelvin or higher produce the blue part of the light spectrum and are ideal for the growth stage of your plants. Lights with a 2000 Kelvin color temperature, on the other hand, produce light in the red spectrum and are essential for the flowering stage.
HID vs. Fluorescent
To artificially create light within the right spectrum for your plants, you have two choices: HID grow lights or fluorescent grow lights.
HID lights are most common in grow lighting. To produce the red and blue spectrum with HID lights, you need high pressure sodium ("HPS") lights and metal halide lights, respectively.
Linear fluorescent grow bulbs come in T12, T8, and T5, each more efficient and compact than the one before it. Today, T5 lights are used almost exclusively. Fluorescent lamps also come in a variety of color temperatures, so look for the right Kelvin rating before you buy.
Calculating Coverage
But how many bulbs do you need and of what wattage?
Coverage varies depending on the type of bulb and fixture you use, but at least as far as HID lighting goes, the "rule of thumb" is 50 watts per square foot. In lumens (the standard measurement of light output), that comes to about 1,500 lumens per square foot for metal halide lamps and 2,000 lumens per square foot for HPS lamps.
Fluorescent coverage is less precise and determined as much by the fixture as by the bulb itself. Unlike HID lights, fluorescent tubes run so cool you can place them as close to the plants as you want. This means the coverage of a fluorescent grow light is roughly the same as the dimensions of the lamp itself.
For more examples, check out our grow light coverage infographic:
Grow Light Coveratge
High Bays
Imagine lighting fixtures in a warehouse. The high bays used for indoor growing are just modified versions of those warehouse fixtures and come in HID, CFL, and linear fluorescent versions. The HID and CFL high bays are great for starter grows, and are only suitable for growing a few plants due to small coverage areas. On the other hand, linear fluorescent high bays are an ideal choice for T5 fluorescent grow lights, as they have larger coverage areas and operate two to eight individual bulbs.
Strips
Linear fluorescent strips are only suitable for growing compact rows of vegetables or herbs, as they only operate one or two lamps.
Open Air HID
These types of fixtures are the most common type of grow light because they produce high lumens, have great coverage, and provide sufficient cooling. Open air HIDs include wing fixtures and parabolic fixtures.
Enclosed HID
Similar to open air HID fixtures, enclosed HID fixtures include air cooled and “cool tube” fixtures. However, these types of HID fixtures offer two distinct advantages over the open air HID fixtures. One, the bulb is protected by a tempered glass lens, which protects your plants and grow area from glass in the event of a bulb malfunction or thermal shock from overspray of water or other liquids. Two, the fixture offers better cooling. Both types of the enclosed fixtures feature flanges on either end for external cooling, allowing you to send a constant stream of air past the bulbs, therefore keeping both the bulb and your plants at a safe temperature.
Timers for Grow Lights
Now that we’ve covered the types of grow light fixtures, we’ll discuss the different types of timers and their importance in your grow project.
Just like you and me, plants require sleep. Generally, plants need 15 to 18 hours of light a day during the growth phase and 10 to 12 hours of light during the flowering stage. For the remainder of the time, your lights should be off. You can accomplish your plants’ lighting needs in a few ways: by manually turning your lights on and off (not really recommended) or by utilizing a simple plug-in timer. Manually turning your lights on and off isn’t recommended for one reason: you may forget to turn them on, or you may forget to turn them off, both being detrimental to your plants’ health. The answer to you plants’ lighting needs is a plug-in timer, offered either in digital or analog format.
Analog Timers
Analog timers are generally cheaper and somewhat easier to use than digital timers. These types of timers have a dial that turns throughout a 24-hour cycle and trippers that turn the lights on and off. You place one tripper at the time you want your lights on, and another when you want your lights off. When the timer hits these trippers, the lights either turn on or off. However, most types of analog timers lose time when there is a power outage.
Digital Timers
Digital timers are definitely the recommended type of timer for your grow light project. These timers work pretty much the same way as analog timers, but offer a few key advantages over the analog timers. For one, they solve the problem of losing time when there is a power outage. These timers have battery backups that remember the time and set points should there be a power outage. Additionally, many of these timers are self-adjusting, resetting themselves for daylight savings time and even calculating sunrise and sunset times based on the time of year.
Ready to get your indoor grow room started? Shop our wide selection of grow lights by visiting our website. And you have any questions or need help finding the right fixtures for your grow setup, call 1-800-624-4488 to speak with one of our lighting experts.
