Grow Lights Simplified: How to Pick the Right Lights for Indoor Plants
If you’re trying to grow plants indoors, grow lights are a great option. But it can also be complex to pick and use the right ones, so it’s important to know what to look for.
Even for the most gifted green thumb, growing plants indoors can be a challenge. After all, it takes specific conditions and light levels to grow plants, and indoor spaces often lack them.
But lacking the natural conditions doesn’t mean you need to forego your dreams of having an indoor oasis. It just means you need to get creative with your approach.
Enter grow lights for plants—your secret weapon for growing even the most finicky and particular plants inside.
In this guide, you’ll learn all about the best light for indoor plants and how to pick the right ones for your needs. From the Kelvin scale to light types, specifications including lumens and watts, and best practices for using grow lights, we have you covered.
What is the Kelvin Scale?
Most people are well aware that plants need light to survive. But what you might not realize is they actually require two types of light to survive:
The Visible Spectrum: This refers to the type of light that we can physically see
The Infrared Spectrum: This refers to the type of light that we cannot physically see
To make matters even more interesting, certain light colors are more important for plant growth than others.
Sunlight contains light from both the visible and infrared spectrums. When plants are growing outdoors, they’re adapted to naturally absorb the necessary amounts of each. But when growing indoors, we need to recreate this light considering color temperature and duration.
We know what you’re asking: what’s color temperature, and how do you measure it?
You measure it using the Kelvin scale.
Color Temperatures in the Kelvin Scale
The Kelvin scale measures colors ranging from blue to green, yellow, and red.
Color temperatures in the Kelvin scale range from 1,000 to 10,000. A color temperature of 1,000 Kelvin would be warm and red, somewhat similar to candlelight. On the other end of the spectrum, 10,000 Kelvin would be cool and blue, like a clear blue sky.
What Kelvin Do Plants Need to Thrive?
Now that you understand how color temperature is measured in the Kelvin scale, you’re probably wondering: what Kelvin do plants need for optimal growth?
The first thing to know is that plants typically absorb red and blue light. And natural sunlight is in the range of 2,700 to 7,000 Kelvin.
So, as a general rule of thumb, if you’re looking to promote vegetative growth, pick lights ranging between 5,000 and 7,000 Kelvin. To promote fruiting and flowering, opt for lights in the 3,500 to 4,500 Kelvin range.
But be mindful that different plants will have different Kelvin needs to thrive, so it’s always best to check with a plant expert when purchasing plants and indoor lights.
Grow Light Lumens
Another important consideration for picking indoor grow lights comes in the form of Lumens: a measurement of the total quantity of visible light emitted from your grow light.
This can get a bit tricky, and here’s why: Lumen measurement is weighted according to a model of the human eye’s sensitivity to various light wavelengths.
And since the human eye is more receptive to yellow light than it is to the blue and red light that plants need most, yellow light is weighted more heavily than blue and red light when it comes to lumen.
As a result, while grow lights producing more lumens look brighter, and those producing fewer lumens look dimmer, lumens are not an absolute measure of the overall power of a grow light and its effectiveness in helping you grow plants indoors.
So, as a generality, you should try to use lumen output in combination with color temperature and consider it a metric for comparing the relative output of different grow lights.
Grow Light Watts
Wattage is one of the most commonly known measurements when it comes to light.
But how does it factor into your grow light selection?
The short answer is it doesn’t have a huge impact on your grow light’s ability to grow plants: watts are a measurement of power consumption but not necessarily of a light’s output or color.
Wattage indicates how much it will cost to operate a light versus how much power it puts out. For instance, a high-efficiency light will give off more light per watt than lower-efficiency ones.
How Many Grow Lights Should You Use?
Once you’ve decided which grow lights are the right ones for your specific needs, the next question becomes one of volume: how many lights do you need to effectively grow plants indoors?
As a best practice, the best way to decide how many lights you need is to determine your plant’s lumen needs and purchase lights that will meet that range. But your safest bet is to consult with the lighting experts from whom you’ll be purchasing your grow lights to ensure you get the right volume.
Once you’ve got your lights, you’ll want to have the fixture between three and six inches from the plant canopy. And you’ll also want to keep an eye on your plants because they’ll tell you if you’ve got the lighting right: weak, leggy plants are an indicator that you’ll need more light.
How Long Should Your Grow Lights Be On?
While all plants have different requirements, most vegetables and flowering plants need 12 to 16 hours of light per day, with flowering plants at the top end of that range—plan on giving most plants at least 8 hours of darkness per day.
What To Do If You Don’t Want Grow Lights
If you don’t want a proper grow light, but you still want to help support the growth of your plants, here’s a hack: simply find a regular light, such as a side table or floor lamp, that has the same socket type and wattage capacity as your grow light bulb. This way, you can turn everyday house lights into grow lights.
There’s no doubt about it: a lot goes into growing plants indoors. But by understanding what type of grow lights to use, why, how, and for how long, you can successfully grow your own indoor oasis.
If you’re curious about picking the perfect planters for your indoor plants, contact us to speak with one of our experts today. We’re here to help answer any questions you might have.