How to Use Grow Lights for Houseplants

Learn how to use grow lights for houseplants to help them thrive indoors year round. My guide has everything you need to know to get started, including the different types of light and which is best, the different types of grow lights for houseplants, and how you should set your grow lights up.

How to use grow lights for houseplants: What are grow lights?

Everyone knows plants need light to grow, but not all light sources are the same. Growing lights allow you to cultivate beautiful indoor plants in any climate, any time of year. There are many different types of grow lights that are all specifically designed to stimulate photosynthesis and help your plants grow. 

Science basics: What is photosynthesis?

Remember learning about photosynthesis in middle school science class? Great, let’s get back to basics for a minute. Photosynthesis is a process that occurs in plants.

It converts light energy into chemical energy that the plant can then use to grow. Photosynthesis occurs differently depending on the plant. This means that plants sometimes require different wavelengths of light to grow.

Grow lights can either mimic the light spectrum of the sun or emit specific wavelengths needed to help an indoor plant flourish. For example, blue light can help with foliage, while red has an effect on root formation and flowering.

What’s the difference between grow lights and traditional lights? 

So what’s the difference between grow lights and traditional lights? Wavelengths and heat. Traditional lights only offer narrow wavelengths, meaning your plants won’t get the right light, and photosynthesis cannot occur.

Additionally, traditional lights give off heat, which can easily scorch and burn your plants. Grow lights, on the other hand, support photosynthesis by offering a wide range of wavelengths, as well as specific lighting depending on your plant’s needs.

Most grow lights also consume less energy and do not give off heat like a traditional bulb, making it safer for your plants.

What are the different types of grow lights?

Picking the right grow lights for your plants can be tricky since there are many different types. The four most popular grow lights are incandescent, fluorescent, LED, and HID. 

1. Incandescent grow lights

These are the most commonly found, least expensive light bulbs; you can find these at a hardware or grocery store. They are the typical light bulb you’d use in a lamp.

However, they aren’t the best choice as a grow light because they give off a lot of heat which can scorch your plants, and they aren’t very energy efficient or long lasting.

2. Fluorescent grow lights

Fluorescent light bulbs are typically sold as long tubes or compact fluorescent reflector (CFL), which you might recognize as a spiral bulb. Unlike incandescent bulbs, these do not produce a lot of heat so they are safe for your plants. The light they emit is also easy on the eyes.

Fluorescent bulbs can give off the full spectrum—warm for flowering, and cool for vegetation. Fluorescents tend to be on the pricier side. However, they last a long time and are very energy efficient.

3. LED grow lights

LED stands for light emitting diodes; these lights are made out of many little diodes that each emit light. These are the most high-tech grow lights as of yet because they produce a wide range of wavelengths while giving off almost no heat. 

Additionally, they do not consume a lot of energy and can be customized depending on which color light your plant needs. The grow lights I have are all LED grow lights, and I’ve been really happy with them.

4. HID grow lights

High intensity discharge lights have become a popular type of grow light for a number of reasons. They put out a massive amount of light and are used by most commercial growers because they replicate the sun better than any other bulb.

You probably don’t need these as a hobbyist. HIDs are made of gas-filled bulbs and electrodes; as electricity goes from one electrode to the other, it reacts with the gas to produce bright light.

There are two main types, Metal Halide and High Pressure Sodium. The former gives off blue light while the latter gives off yellow light.

What color grow lights do houseplants grow best in?

So now that we’ve covered the different types of bulbs, let’s talk about the different colors of light they emit. You’ve probably noticed that some grow lights are purple, whereas some look like regular indoor lights.

Cool 400nm–500nm

Violet, blue, and green are all on the cool spectrum. Violet light is typically only useful when combined with red and blue. It can be used to make a plant’s color, taste, and smell more prominent. 

Blue light is extremely important for plant growth; it is absorbed by chlorophyll which is a big part of photosynthesis. Green light isn’t as useful for plants since they reflect most of it (which is why plants are green). However, your plant should still be receiving some green light for proper growth. 

Warm 580nm-700nm

On the warm end of the spectrum are red, orange, and yellow. Red light is vital for plant growth, especially when combined with blue. Red light helps grow stronger plants, more vegetation, and even helps flowering. 

Far-red light also signals germination and regulates flowering. Orange and yellow aren’t quite as useful, but they are still important to overall growth. 

The best of both worlds: Full spectrum

Full-spectrum grow lights are the closest to real sunlight and will help your plants grow the best. Natural sunlight emits all spectrums of light, even ultraviolet and infrared, which aren’t visible to the naked eye. 

You might be wondering, if blue and red light are the most important wavelengths for plant growth, then why should I worry about other wavelengths? By only giving plants red and blue light, you are weakening your plant and possibly stunting its growth. 

There’s a reason why sunlight, which emits a full spectrum, is necessary for plant growth, so grow lights should mimic sunlight both in intensity and wavelengths. So it’s best to choose a full-spectrum grow light to help replicate that as closely as possible.

Grow bulbs vs grow light fixtures

Grow light bulbs are the most convenient, cost-effective option. You simply take an old lamp or fixture, and swap out the bulb with a special grow bulb. This works with incandescent, fluorescent, and LED bulbs. 

This LED bulb is a perfect grow light for your houseplants, especially in a common area like the living room. It threads right into a normal fixture and emits proper wavelengths for your plant that are still easy on the eyes.

If you’re only using one bulb, though, it won’t suffice for multiple plants. Lighting fixtures are a better option if you have multiple houseplants; however, they are pricier than a bulb.

Grow light fixtures are uniquely designed to deliver proper light to all your plants. They won’t give off heat and provide a broader spectrum of light than individual bulbs do. 

I personally don’t use lighting fixtures due mostly to space, but they are also pretty expensive. A cheaper alternative to lighting fixtures are LED strips. These Mosthink LED Grow Light Strips are affordable, easy to set up, can be used for several plants, and emit a full spectrum, mimicking natural sunlight.

How to set up single grow light bulbs

The possibilities are endless when it comes to setting up grow lights in your home. You can go for functionality, which is great if you’re seed starting or growing smaller foods like lettuces.

Or you can aim for decorative, aesthetic, and functional like I do with a greenhouse cabinet and my hanging bulbs. First let’s talk about using single grow light bulbs. If you just have a few plants that you want to light, you can use the single bulbs.

I have a few hanging from the ceiling to help light some of my plants in darker areas of the home. To hang these, I just use a long cord and little cup hooks screwed into the ceiling.

Since plants should not receive light 24/7, make sure your grow lights are on a timer. I use these smart plugs to set a schedule so I don’t risk forgetting to turn off the grow lights. I leave them on for 8 hours a day, and they don’t have brightness dimmers.

How to set up grow lights on shelving or in a cabinet

Next let’s talk about setting up grow lights on shelving or in a cabinet. Pick out a good, sturdy shelf or cabinet. A wire shelving unit is great because they’re easy to find at the hardware store, relatively inexpensive, and they’re easy to set up and keep clean. 

I went for an Ikea glass cabinet, Fabrikor. You can see my whole Ikea glass cabinet setup post here. It’s a beautiful little decorative cabinet with glass windows and glass shelves that allow light to easily pass through. Ikea has a bunch of great, affordable options for greenhouse cabinets.

Next, you’ll have to decide how to set up your grow lights. For a larger shelf, like a wire shelving unit, you’ll probably want a longer grow light.

Fluorescent tubes are a great option because they use 75% less energy and last 10x longer than traditional bulbs. To set these up, use S-hooks to attach to the shelving unit. 

Keep in mind, as your plants grow taller, you’ll need to raise either the shelf or the grow lights. For my greenhouse cabinet, I chose these LED strips because they don’t require screws; I simply used double sided tape to attach them to the top of the cabinet. They also don’t give off heat, so my plants can safely grow in close proximity. 

Make sure your grow lights are on a timer. The LED strips I use in my greenhouse cabinet have a convenient 2, 4, and 8 hour timer. I keep it on an 8 hour timer at 100% brightness. I found that this was best for my plants after some trial and error.

How close should grow lights be to houseplants?

Hanging grow lights is the best way to mimic the sun because it delivers light from above. If you place grow lights at an angle, it might not distribute the light evenly.

The light should always reach the entire plant, otherwise they will grow slanted in the direction of the light source. Incandescent grow lights should always be at least two feet away from your plants because they give off a lot of heat and could damage the foliage.

Fluorescents should be at least one foot away from your plants, so as your plant grows be sure to adjust the height of the grow light. LED lights give off almost no heat at all, so it’s safe for houseplants to grow within 6 inches of them.

That makes LED lights perfect for tight spaces like shelving or greenhouse cabinets. I personally use all LED lights to take the guesswork out. Keeps things easy!

How long should I leave grow lights on for?

In addition to proximity to the plant, the time you leave the grow lights on for and the strength are critical parts of the equation. When plants are exposed to light, they’re hard at work photosynthesizing.

So if you overexpose your houseplants, they will “burn out.” Sometimes literally. And it could damage their foliage, prevent flowering, and dry them out. 

Generally, plants need at least 8 hours of darkness everyday, sometimes more. Darkness is an important part of a plant’s growth because that’s when it uses the energy it has stored up to grow and flower. 

Most houseplants will do great with 8 to 10 hours of sunlight per day, though flowering plants might need more. Above all, plants like consistency. Keep a timer on your grow lights to give your plants a light cycle that will help them grow and stay healthy.

What I do with my grow lights…

This becomes more of an art than a science depending on the plants you have and the grow lights you use. I will tell you how I have approached determining this:

• First, I use all LED lights to take the guesswork out of proximity and avoid heat and burns.
• Second, I keep the lights on at full strength (if they have intensity levels) for 8 hours a day.
• Third, I place the plants about a foot away from the lights and move them closer over a few weeks as I monitor how they do to the light. Alternatively, you could put the lights on a lower setting and put the plants right under them; then gradually increase the intensity and monitor how your plants are doing.

Once you find a setup that works for your space and plants, stick with it! Your plants will start thriving with a little extra light, and you’ll be able to extend your growing season and help your houseplants thrive!

Recap: Grow lights I’ve personally used

Just to recap, here are a few grow lights I am currently using, either hanging from the ceiling or in my cabinet. I’ve also used the strip grow lights on DIY open plant shelving before I got my greenhouse cabinet.

• Mosthink Full-Spectrum LED Grow Light Strips
• GE Full-Spectrum, 9-Watt LED Grow Light Bulb
• Sondiko Full-Spectrum LED Grow Light Strip

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