Can You Use Mirrors in a Grow Room?


If you’re just starting up your grow room or looking for ways to improve it, you may have come across some questions regarding how light and reflection affect your plants. Mirrors are an everyday item that is used, but are they really good for all aspects of growth?

Can you use mirrors in a grow room? Using mirrors in your grow room is not recommended due to the infrared light they project. Mirrors seem like a good idea to redirect light to your plants, but they cause additional heat in a concentrated area that may end up burning the plants. There are far better ways to achieve light distribution than mirrors.

While finding the right balance in all elements of your grow room, there may be some trial and error that is inevitable. But doing some additional research first will help save future headaches and confusion over why plants may not be thriving in certain conditions. 

Why People End Up Using Mirrors

There are a few different reasons growers think mirrors will be a good addition to their grow house. The logic makes sense initially, but after learning more specifics, you realize they are not going to be an asset to your plants.

  • They Look Cool

We get it. A few mirrors on the walls and a massive mirror along the ceiling gives your grow room an impressive aesthetic. It looks cool, and it also makes it look more bountiful. So, if you’re trying to get some cool photos of the plants and the room, this may be a great way to land some great shots, but then take the mirrors down.

  • It Seems Like The Logical Choice

When you’re growing cannabis, light is going to be one of your primary sources of fuel and energy for your plants. Most plants, but not all, thrive when they are receiving direct sunlight. So, when you are looking at light options for your indoor plants, mirrors seem like a logical choice to redirect sunlight from outside or additional lighting that you have set up inside.

Recently, as we have become more conscious of sustainable practices as a society, reflectors have become even more popular. While you can use high-intensity discharge lamps, you don’t want to be running dozens at a time. This will only run up your electric bill and cause unnecessary electricity use. 

So, the use of reflectors has circumvented the use of additional lights. And what do most people think of when they think of reflection? Mirrors. They are cheap, and you can get them in all sizes, making them easy to use around a grow room. So, it makes sense that this has become a go-to reflector, even though it’s far from ideal.

Will Mirrors Work in a Grow Room?

Mirrors will reflect light in a grow room, but they will typically do more harm than good.

The main reason why mirrors are bad for grow rooms is because of the type of light they reflect, and how they reflect it. Mirrors directly reflect infraredOpens in a new tab. lights. Infrared light = heat. 

According to High TimesOpens in a new tab., the ideal temperature of the grow room will depend on the stage of the plants. But most stages of growth, before drying, will require around 70-80 degrees F. 

You might ask yourself, “Why would heat be a bad thing if the plants need a relatively balmy atmosphere?” 

The temperature of the atmosphere around the plant is different than a direct heat source beaming into a concentrated area. The heat that reflects from a mirror’s surface is going to be an intense bolt of heat and light on a specific area.

That intensity will create too much heat and can burn sections of the plant. And like many other plants, there is a specific balance that is required for proper growth. When temperatures get too high in a room, they can begin to cause a release of flavonoids and cannabinoids. The additional source of heat from mirrors can start to cause that process as well.

What Are the Best Reflective Materials for a Grow Room?

So, if mirrors create too much dangerous heat and tin foil can be troublesome because of insects finding a home within the crinkles – what is the best type of reflective material to use in a grow room?

White Reflective Paint

White reflective paint is one of the best ways to reflect light in a balanced way and not cause any additional damage. It is also an easy solution, as it does not require extra maintenance.

You may need to slap on an additional coat from time to time, but these will be few and far between compared to continuous adjustments of materials used throughout a grow room for reflective purposes. 

It’s a simple solution and won’t break your bank, as you can pick up a can relatively cheap, like this BEHR White Base Dead Flat Interior Paint at Home DepotOpens in a new tab..

Using a flat white latex paint on the walls and ceiling of your grow room will be an effective way to keep light bouncing throughout the space and onto your plants. It provides a balanced light and will not translate into the hot spots that a mirror causes.

Flat white paint will reflect at a rate of around 75%-85%. 

Tin Foil / Mylar

Tinfoil is often used as a reflective surface due to its inexpensive price tag and ease of use. But if you use foil or Mylar, make sure there are no creases or crinkles in the material once it is up on the wall. Those little nooks will be a perfect hiding place for insects waiting to eat through your plants. 

Not only that, but the creasing also decreases their ability to reflect light to their full potential.

Always ensure the cleanliness of the foil as well as keeping it straight and undamaged.  Otherwise, it may end up being a new home for enemy #1. 

When using either substance, you will want to make sure the room temperature stays low enough, as they will produce some additional heat.

Tinfoil and Mylar reflect at a rate of around 90%-95%.

Pro Tip: Using a mylar tent can be a great option. If you want to set up multiple tents around a grow room, you can get the benefit of Mylar’s high reflectivity without having to worry as much about it creasing because it was professionally assembled into the inside walls of the tent. MediumOpens in a new tab. released a comprehensive review of some of the best tents on the market.

Foylon

When you look at Foylon, you may think it is the same as Mylar, but there are some key differences. The main difference being in its thickness and durability. It won’t wrinkle as easily, and it will last longer without as much tearing and ripping. But that also adds a little onto the price tag.

Foylon will reflect at a rate of around 95%-100%, which is, of course, an impressive range. Similar to foil and Mylar, it will bring some additional heat into space, so always have proper air ventilation and constant temperature monitoring.

Although Foylon, foil, and Mylar all cause additional heat, they will not create the concentrated hot spots that mirror cause. They are better at distributing the heat throughout the space than beaming down on a small area, causing burns as mirrors do.

Mirrors, Light, and Reflection in Grow Rooms

Mirrors will not be your best options for helping your plants grow properly when finding ways to reflect light throughout your grow room. The other options we mentioned will all do a better job of keeping your plants safe.

White reflective paint will be the most balanced and easiest way to keep your plants safe while providing the additional light and reflection needed for an indoor grow room.

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