Grow Lights – What They Are and How to Use Them

What are grow lights? They're a substitute for natural sunlight, a way to give indoor plants the light they need to survive. While your home may seem plenty bright to you, the amount required by a lot of plants is actually much higher. That's where this supplement comes in.

Grow light setups can be very simple or extremely complex, depending on how involved you want to get, and whether you're coddling houseplants or starting seeds indoors. Let's explore the basics and figure out which is right for you.

The Light Spectrum

While sunlight looks white to you and me, it's actually made up of different colors, and you can buy grow lights that reflect those colors. Here are the three colors of grow light you're likely to encounter.

• Blue Light (400-500nm): Essential for vegetative growth and "bushy" plants. It prevents plants from getting leggy.
• Red Light (600-700nm): Crucial for flowering, fruit production, and seed germination.
• Full Spectrum: These lights mimic the sun by providing a balance of all colors. This is generally the best choice for all-purpose indoor gardening.

Types of Grow Lights

LED (Light Emitting Diodes)

In the past ten or so years, LEDs have become the new standard bulb pretty much everywhere, and that includes grow lights. They're extremely energy efficient, so they're cheaper to run. They also give off very little heat, which means they don't dry out the soil, and you can put them right up next to your plants without scorching the foliage.

Modern LED grow lights often come in "Full Spectrum" options that mimic the sun, though you may also see "blurple" (blue and red) lights designed specifically for targeted growth phases. When shopping for LEDs, look for the PPFD (Photosynthetic Photon Flux Density) rating rather than just wattage. This tells you exactly how much usable light is actually reaching your plant's leaves.

Fluorescent Lights

Fluorescent lights are cheap, easy to use, and readily available in lots of shapes and sizes, so naturally they're a favorite. Compact Fluorescent Lights (CFLs) are also a great choice for small spaces or single plants because they can be screwed into standard lamp sockets.

It's important to keep in mind that fluorescent bulbs lose their intensity over time. Even if the bulb still looks bright to your eyes, the spectrum may have shifted or dimmed enough to slow plant growth. This means you should change your bulbs out every 12-18 months. Bear that in mind when thinking about cost effectiveness.

HID (High Intensity Discharge)

High-Intensity Discharge lights, which include Metal Halide (MH) and High-Pressure Sodium (HPS), are the heavy hitters of the indoor gardening world. These are the lights the plant pros use for large-scale indoor gardens or fruit-bearing trees.

They consume a large amount of electricity, need specialized ballasts, and generate intense heat, which requires a dedicated ventilation or exhaust system. You don't want to go down this road lightly.

Incandescent Lights

These are your run-of-the-mill, old-fashioned light bulbs. They give off heat, they're inefficient, and they're too far on the red end of the spectrum to be a good alternative to sunlight. They really shouldn't be relied upon as the primary energy source for your indoor garden. Luckily they're being phased out of common use as we speak, so the temptation to put them over plants is dwindling.

How to Use Grow Lights

1. Give Your Plants a Rest

You're using grow lights to mimic sunlight, and what does the sun do half the time? It goes away! Grow lights are not meant to be kept on 24/7. For seedlings, they should be on 14-16 hours per day. For houseplants, 12-14. There are all kinds of timers on the market (and many built straight into the lights) that can run this schedule for you.

2. Adjust for Growth

Grow lights help your plants... well... GROW! That means they're going to get taller, and you'll have to move the lights with them. This is especially true for seedlings, which can gain height at a monumental rate.

If you notice your leaves look bleached or have brown or crispy spots, that's a sign that the light is too close. If your plant is leaning toward the light or looks stretched out, that means the light is too far away.

3. Clean Your Bulbs

Did you know dust on your lights can reduce their efficiency by up to 20%? Wipe down your tubes or LED panels once a month (when turned off and cool) to ensure maximum light penetration.

Our Recommendations

Tyler Schuster, our resident grow light expert, swears by his Spider Farmer light, which is available on Amazon. It's the real deal. If you're looking for something a little cheaper, here are some good alternatives.