LED Grow Lights FAQ: 8 Important Facts (Explained!)

Grow lights are used to replace sunshine in artificial, indoor growing environments. What kind of grow lights you need depends on many factors, including (but not limited to) the type of plant, the stage of growth, and the desired results. Many people consider LED lights to be superior in that they are cheaper, safer, and you can even control the spectrum of light very carefully.

More and more, people are becoming interested in gardening, but not everyone has the outdoor space to do it in. In fact, for many people, the types of plants they want to grow may not match the climate or soil of the region they live in. The solution? Grow lights! 

In this article, we’re going to show you some of the most basic questions that any aspiring indoor gardener may have about LED grow lights.

Are LED lights good for growing plants?

The short answer: yes, LED lights can be very effectively used to grow plants. Not just any LED lights though, you have to be sure that you are purchasing equipment that has been specially designed to function as such.

 If you attempt to use a domestic LED reading lamp to grow your vegetables, it’s very unlikely you’re going to see any results, and there are several reasons why. For one, the spectrum of light and the power of the bulb should be of sufficient strength and quality to provide your plants with the energy that they will need to grow.

LED or Fluorescent?

LED grow lights are superior to Fluorescent in several ways. For one, they are incredibly efficient at turning electricity into light. 

This is not the case with other types of bulbs. Fluorescent bulbs, to use an example, turn some of their electrical input into heat and other kinds of radiation. The result is that your electricity bill is higher; bad news not only for your wallet but for the environment too. 

While some studies have shown that plant-mass output from fluorescent farms tends to be higher, the additional costs and risks mean that it probably isn’t worth your money.

What is the best grow light spectrum?

 To oversimplify, visible light is constituted of red, blue, and green light; everything that we see day-to-day is a reflection of those bandwidths of light. 

The fact that we perceive plants as green means that they actually reflect green light. The logical conclusion here is the correct one; that by and large a combination of red and blue LED lights has been shown in studies to be highly effective at encouraging plant growth in most species that are primarily green.

That said, many species do absorb and process green light just as effectively as red and blue: as with anything in this article, it will depend on what exactly it is you are attempting to grow. It is worth noting that a full spectrum of red, blue, and green will usually produce fruitful results.

Are LED lights safe?

Safer than the alternatives. The fact that LED lights don’t give off significant amounts of heat means there’s far less potential for you burning your hand if you touch one. Likewise, the chances of your growing space catching fire are massively reduced when compared to the available alternatives. 

Incandescent bulbs, for example, are literally controlled fires held within a glass vacuum bulb; obviously not the safest thing to leave unattended and surrounded by vegetation.

Precautions should however be taken when it comes to the placement of your lights; just because a risk is reduced, doesn’t mean it’s non-existent. Be cautious when installing your grow light rig and follow the instructions provided carefully.

How High Should Your Grow Lights Be Above Your Plants

As a rule, you will want to keep your grow lights at a sweet spot, where they are getting sufficient light and energy for your growth goals while maintaining a safe distance that doesn’t overpower them. This means that there isn’t a one-size-fits-all answer to this question. 

This distance your lights will hang at has to be calculated by you and will depend on what breed of plants you are growing, the strength of your lights, the size of your space, and so on.

Why do different grow lights need to be hung at different heights?

This depends on the kind of power output that your grow lights have. 

You can have LED grow lights that operate on a wattage as low as 15 watts and go as high as 4000+ watts. The former you could use for growing things like cress and other salad toppers, with the higher ranges being used for growing hardier crops. Due to the different levels of heat output that these lights produce, you should hang them at different heights.

Failure to do so successfully can result in plant ‘bleaching’ which affects the quality (or taste) of your produce. In general though, due to the lower heat output from LED lights, you can expect it to be a matter of tens of inches as opposed to several feet.

Can I leave my grow light on 24 hours a day?

In general, it’s advised that you don’t leave your grow lights on 24/7. This isn’t just a cost-saving measure either. Your goal is to simulate and optimize the growing environment for your plant, not to maximize inputs. 

Plants are designed to operate with a day-night cycle, and as such leaving the lights on all of the time can cause many plants to grow too quickly, meaning that they can fall over, break or otherwise die. You should consider the use of a timer to reduce the amount of involvement you need in turning your rig on and off.

How Many LED Watts for Seedlings?

When you’re starting to grow anything, you’re going to be growing from seedlings, whether it’s watercress or an oak tree. While there are more factors than wattage at play, you’re going to want to use a light of around 10w-30w to start with and keep it relatively close to the soil. 

We would advise a minimum of 8 inches and a maximum of 30 inches. As the plants start to sprout, try to gauge by eye if they look spindly or stretched; if so move your light closer. Keep adjusting based on your own judgment of how the seedlings grow. Remember; growing plants is an art as well as a science!