Updated February 26, 2022 by Mark Marino
There are a million and one reasons to grow plants indoors. As the climate changes, urban sprawl increases, and the availability of affordable farmland decreases, being able to grow plants anywhere becomes not only a valuable skill but a technology to innovate on. And like any technology, indoor growing has fundamentals.
Two of those fundamentals are well documented. Watering plants is such a basic practice that it has basically been perfected by nature for hundreds of millions of years. The second is fertilizer, which has been perfected by chemists making clean and ultra-efficient fertilizer you can get at the store. But there is a third fundamental.
Indoor growing needs light to replace sunlight, and those lights can be made at home. It is not necessarily an easy task, however. You are fighting an uphill battle against the laws of physics and the nature of light to get things behaving how you need them to. You can start by making a filter.
Filtering Normal Light
Fluorescent lights can be used to feed plants their required sunlight, but it will require a few extra components. For instance, most lights do not output the correct wavelength of light to feed plants enough to sustain them. What does this mean though? What is a “wavelength” anyways?
Light exists on a spectrum. On one end of the spectrum is the light that hits your eyes more frequently. This is because it has a shorter “wavelength”, and as a result of this shorter wavelength the light takes on a different color. The wavelength is the distance between the waves of light. A shorter wavelength means more light.
Purple and blue light has the shortest wavelength of all visible light. A short-wavelength means the light collides with anything it touches more frequently. This means that purple and blue lights become a feast for light-starved greenhouses. It also means that they can light up a space as small as your closet.
A plant feeding off of blue light will get nearly double the nutrition than it would from an orange light of the same intensity. It is a simple matter of the blue light “hitting” the plant at a higher frequency than the orange light. Blue light is recommended over purple light, however.
Even though purple light has an even higher frequency than blue light, it can actually be so high that plants can’t absorb it. There are many kinds of light that are not visible to the human eye for the same reason.
In this case, the human eye can identify a color of the light (purple) that plants have trouble absorbing. You can use lights to supplement your greenhouse even if it gets direct sunlight. This is because the big danger of sunlight is the heat more than the light.
As stated before, there are many types of light that are not visible, and these types of light are what carry heat with them. Gamma rays and infrared light is the light that generates the most heat. Luckily, you will actually have a hard time finding any light fixtures that output this.
What this means is that if you have enough lights, filtering them to be purple or blue will actually make them better for your plants. This is because all the other light will be filtered out, so your plants will be able to feed more efficiently, and the light they find valuable will get to them without being cast off or drowned out.
Are LED Lights Better For This?
Yes, certainly. You will be hard-pressed to find anyone recommending DIY lights over just buying colored LED lights. Even non-colored LED lights are better for this sort of thing, as they are so energy efficient that they pay for their own filters eventually.
The only time you should use normal lights is when you already have the components lying around to make them. It requires about double the number of LED lights, as well as filters for each light, in order to do DIY normal lights that can support plant life.
What Lights Are Best For A DIY Job?
If you are determined to set up a DIY light job, you will likely want T8 or T12 tube lights. These allow you to do two things: The first is that they are easy to affix to any shelf that your plants sit on. They can also be affixed easily to plant pots if you are growing a larger crop indoors, such as tomatoes or strawberries.
The second thing that is beneficial about tube lights is that they are the easiest to attach filters to. There are some dedicated filters that will essentially be colored shrink wrap. These can be wrapped around lights, though you do have to be careful that your lights do not damage them from heat build-up.
Luckily, T8 and T12 lights generally do not get hot enough for this to be a concern. And besides, another great asset of these tube lights is that not only is it easy to affix them to other things, but it is also easy to affix other things to them. All you need is some close pins or paper clips to attach a filter onto a tube light.
If there is any objective advantage of tube lights of LED lights, it is that tube lights are usually designed to be more durable. This means that if you find yourself relocating your crop frequently, you can remove any lights that are obstructive to this without worrying about breaking them.
This is especially important given that many indoor plants, such as the aforementioned tomatoes and strawberries, require frequent pruning of their roots to ensure that they do not become crowded in their own containers. If you had to delicately remove every light every time you had to do this, it would be exhausting.
Instead, removing these lights is easy. This means that even if you have extremely healthy plants that need to be pruned once a week, your lights will be no worse for wear. This versatility might be the deciding factor in whether you use normal lights or LED lights, so do not overlook it.