Reflective Materials to Use In Your Grow Room

And God said, 'Let there be light.' But imagine if half of that light took a detour to some other planet instead of shining down on Earth. Not very efficient, right? The same goes for your grow room. 

Without reflective materials, precious light from your grow lamps spills onto walls and floors, doing absolutely nothing for your plants. Reflective surfaces, however, bring that wasted light back into the fold, ensuring every photon gets to work its magic. 

Whether you're chasing bigger buds or faster growth, the right reflective materials can make all the difference in your cannabis-growing journey. Here's everything you need to know about them. 

Why Do You Need Reflective Materials in Your Grow Room?

Reflective materials do exactly what their name suggests — they bounce light off walls and redirect it back to your cannabis plants. Think of them as your grow room's way of making every photon count.

Here's the deal: the light hanging above your canopy doesn't beam straight down in a perfect line. Instead, it spreads out in a cone shape. The center of the cone hits your plants directly, giving their leaves and buds a healthy dose of light. But the light on the edges? That spills onto the walls and floor, going to waste if those surfaces aren't reflective.

Using reflective materials lets you redirect this leaky light back into your growing area. This added light fuels photosynthesis, accelerates growth, and ultimately contributes to bigger, better buds.

In fact, by lining the walls of your grow room with reflective materials, you can boost light exposure by up to 30%. And the best part? You're not using any extra electricity or adding more lights. You're simply maximizing the light you already have. More light means happier plants, faster growth, and better yields.

Best Reflective Materials: From Worst to Best

When it comes to reflective materials, there's a range of options to suit your needs and budget. While some materials bounce light really well, more affordable options can still get the job done without breaking the bank. Here are some of the best choices.

1. Aluminum Foil

Reflectivity: 55–60%

Aluminum foil has a few advantages, especially if you're working with a tight budget and a small space to grow just a few plants. It's cheap, easy to find, and can recover over half of the light that would otherwise vanish into your walls. In addition, it can handle heat to a certain extent so it works with high-intensity grow lights.

However, there are quite a few disadvantages that may make you use other reflective materials. After all, you must use something that's safe. 

One major disadvantage of using aluminum foil is that there's a big risk of hot spots. The reflective surface can create strong beams of light that cause uneven growth and burn the plants as well. 

And, if you've ever used aluminum foil to wrap food or for some other purpose, you already know that it tears, wrinkles, or crumples pretty easily, which decreases its reflectiveness, making it difficult to use again. Also, wrinkles and creases scatter light unevenly which reduces efficiency as compared to Mylar or reflective paint.

Most reflective materials can be reused again. Naturally, you don't want something that forces you to purchase it for every growing cycle. But, if you're thinking about reusing aluminum foil, you'll be in for a big surprise as it's very challenging to clean aluminum foil (if it survives one full growing cycle) without damaging the surface since dirt and condensation collect on it.

However, if you have no other option other than using aluminum foil, make sure that you use it correctly. Most growers think that the shiny side is better, but in practice, it may create hot spots. The dull side reflects light more and is better for using it in the grow room. And, if the foil is loosely attached, it can sag or fall and cause shadows or block light, so fasten it tightly with some strong adhesive tape or staples.

We already spoke about hot spots, so you should pay more attention to increasing the ventilation or you'll struggle a lot to reduce the temperatures. Insufficient ventilation, can damage plants and destabilize the growing environment. 

So, in a nutshell, aluminum foil is inexpensive and easily accessible, but it could potentially decrease the efficiency of the grow room if used alone.

Thus, consider pairing it with other reflective materials for more efficiency in the long run. You can also use it in smaller sections or for temporary fixes. However, you'll need to keep re-installing new sections as the foil can disintegrate easily. 

2. Emergency Blanket

Reflectivity: 60–70%

Emergency blankets aren't just for survival kits — they're a budget-friendly way to improve light distribution in your grow room. Made of Mylar (a material we'll get to in a bit), these blankets are lightweight, affordable, and easy to use. 

Each blanket typically covers an area of about 210 × 130 cm, though sizes may vary. You can tape the edges or use double-sided adhesive strips to secure them. They're a quick, hassle-free solution that works well without requiring a big investment.

Benefits of Using an Emergency Blanket

• Emergency blankets are very cheap and easily available, making them an attractive choice for budget growers.
• They are easy to use, cut, and apply to a surface, which is great for temporary or makeshift grow rooms.
• Emergency blankets collapse down nicely, taking up very little storage when not needed.
• The fabric is water-resistant, so it is less likely to get mold or mildew. 

Disadvantages of using an emergency blanket

• These thin emergency blankets can rip, wrinkle, or crumple which can reduce their reflectivity over time.
• The emergency blanket's top layer is not uniformly dispersive, creating hot spots from reflected light which affects its efficacy.
• Emergency blankets are not very durable because they're very fragile and need to be changed frequently.
• It's challenging to install the material with no wrinkles or sagging.
• The wrinkly feel of the material can create noise when used or when air is circulating in the grow room which may be annoying.
• Emergency blankets are much less effective than mylar or panda film which are specifically designed for grow rooms. 

3. White Paint

Reflectivity: 80–90%

If you're growing in an open room, a simple coat of white paint on the walls can do wonders. White surfaces reflect light, whereas darker colors soak it up like a sponge. A good-quality white paint can bounce up to 90% of the light back onto your plants — without a major dent in your wallet.

The best part? It's as easy as it gets. Grab a roller, slap on some paint, and you're done. No fancy DIY skills are required. Plus, you might already have some leftover paint in your shed, making this option even cheaper.

Different Types of Reflective Paint

1. Flat White Paint

• Reflects 80-90% of light making it one of the most efficient. 
• A flat (matte) finish will not scatter light but will evenly spread light all over the grow room.
• In terms of cost, it is cheap and easily available at hardware stores.

2. Semi-gloss Paint

• It doesn't reflect light as much as flat paint, but it's still suitable for smaller setups.
• Easier to clean than flat paint but can scatter light slightly.

3. Specialized Reflective Paints

• Designed specifically for high reflectivity in grow rooms or industry.
• Usually costlier but very strong and optimized for light efficiency.

But, there are some types of paint you should totally avoid:

Glossy Paints

• Glossy paints reflect light in an uneven manner that creates hot spots and affects efficiency. 
• Tends to absorb light instead of reflecting it, which means it wastes lumens. 

To maximize the reflection from white paint, here are a few things you can do: 

• Make sure the walls, ceilings, and other surfaces are clean, dry, and free from debris and grease so that the paint will stick.
• Once you fill holes or cracks with filler, sand down rough patches to create a smooth surface that makes the paint shine.
• Use plastic sheeting or painter's tape to protect floors, windows, or grow equipment from accidental splatters.
• For maximum even application, use a roller with a smooth or medium nap. To ensure that everything is covered, use brushes for corners and edges.
• Paint the flat white paint at least twice for uniformity and reflectivity. Let the first coat dry thoroughly before applying a second one.
• Stay away from thick layers as this leads to dripping and uneven drying that affects reflectivity.
• Make sure to cover anywhere a shadow would be cast, such as in the corners and on the ceiling edges.
• Regularly wipe painted surfaces with a damp cleaning cloth or sponge to remove dust or stains. Don't use an abrasive cleaner that strips paint or reduces reflectivity.

4. Panda Film

Reflectivity: 85–95%

Panda film is a favorite among growers for a reason. It's durable, highly reflective, and super versatile. As the name suggests, it's black on one side and white on the other. For maximum efficiency, make sure the white side faces the plants.

Installing Panda film is straightforward too. Use duct tape or a staple gun to secure it to walls or grow tents. It's also cost-effective, with a 20 × 2m roll priced at around €25.

Advantages of Panda Film

• While the white side reflects around 85-90% of the light to ensure the plants receive light evenly, the black side stops light from getting in and leaking, which can severely affect the flowering stage of the plants.

• Panda film is less expensive than materials like Mylar, which makes it easy for growers to pick.
• It is durable and tear-resistant for long-term use.
• It's also water resistant and resists mold and mildew, making it suitable for highly humid environments. 
• It is lightweight and flexible and you can hang, cut, and clean it effortlessly, making it easy to use permanently or temporarily.
• The white side will help with light diffusion, thereby eliminating hot spots and benefitting the plant's growth.

Disadvantages of Panda Film

• Although the light reflectivity is good, it's lower than that of Mylar, indicating it's not as effective at maximizing light as Mylar.
• Thinner Panda Film versions might get punctured or torn during installation or heavy use.
• As it is made from plastic, Panda Film is not bio-degradable and may conflict with green growing practices.
• Even though the black side does a good job of blocking light, it also absorbs heat. Additional ventilation or cooling may be required in smaller grow rooms.

5. Orca Film

Reflectivity: 90–95%

Orca film is like panda film's tougher, more refined sibling. Made with white plastic microfibers, it reflects and scatters light more effectively, giving your plants a uniform glow. It's also tear-resistant, easy to clean, and mold-proof — perfect for long-term use.

However, this durability comes at a cost. A 10 × 1.4m roll of orca film will set you back around €100. But if you're after top-notch performance and longevity, it's worth the splurge.

Advantages of Orca Film

• The light does not cause hot spots since it spreads evenly across the grow room, maximizing the growth. Orca film reflects at least 94-98% of the light, similar to or better than mylar.
• This material doesn't tear, scratch, or wrinkle easily which makes it durable and reusable.
• Can handle high humidity, temperature changes, and general wear and tear that's common in grow rooms.
• Mold, mildew, or algae won't build upon a non-porous surface. Still, you can wipe it down easily using a damp cloth.
• Orca film, unlike some reflective materials, does not lock the heat in, helping to keep temperatures steady in the grow room.
• This is not made from any toxic material. It is also recyclable and more eco-friendly than plastics.
• Made of thick material that acts as a light barrier to stop the external light that may affect the photoperiod.
• The matte finish provides diffusion for glare-free light to ensure light is distributed evenly.

Disadvantages of Orca Film

• Orca film is one of the priciest reflective materials on the market, which can be a restriction for budget-minded growers.
• It may not be easily available like Mylar or other reflective materials, which means you may have to pay a lot for shipping when you source it from a far-off location. 
• Because of its thickness and stiffness, it is more difficult to cut, manipulate, and install it on a large surface than a more flexible material, such as Mylar.
• Proper installation is very important to avoid gaps. Also, the adhesives you use should be strong enough to support the weight of the material and prevent sagging.
• Even though it is very useful, Orca film doesn't look as sleek as Mylar or reflective paint, which may be important to some growers.
• Orca film is good for diffusing light. However, it is not as versatile as Panda film, which reflects and also blocks light.

6. Mylar

Reflectivity: 90–95%

Mylar is the gold standard for grow tents, and for good reason. With reflectivity of up to 95%, it ensures your plants get every bit of light they need. You can also purchase Mylar sheets to line open grow rooms or greenhouses.

It's budget-friendly too, with a 5 × 1.4m roll costing roughly €10. The only downside? Mylar is delicate, so handle it carefully to avoid rips and creases. Installation is a breeze with tape or adhesive spray.

Whether you're painting walls or lining your grow tent, your choice depends on your budget and setup. White paint is perfect for simplicity and affordability, while materials like Mylar and Panda film offer premium reflectivity for larger or more advanced spaces. 

Advantages of Mylar

• It reflects up to 90-95% of light, enabling maximum light use in the grow room. It also covers a large area to reduce shadows for uniform growth.
• Simple to install, use, and reuse in different grow room setups on walls, ceilings, and areas with little space.
• It can be made to fit any custom shape or area you want.
• This reflective surface helps control heat in the grow room as it reflects as much light energy as possible rather than absorbing it. 
• Plant covers are offered in a range of thicknesses (typically 1 mil to 4 mil) and prices, allowing growers to select according to their budget and durability.
• It's water- and moisture-resistant, making it perfect for growing rooms where moisture levels are high.

Disadvantages of Mylar

• Over time, Mylar will accumulate dust, dirt, and moisture, all of which can degrade its reflectivity. Thus, use soft and lint-free clothes for cleaning the surface.
• If the surface is not positioned or installed correctly, it can create glare and hot spots that harm plants or cause uneven growth.
• Over time, Mylar will deteriorate with constant exposure to heat, moisture, and light.
• It can lose its reflective ability quicker than thick and tough materials like Panda or Orca film.
• Mylar plastic polyester is not biodegradable and adds to the pile of plastic waste. It's not as eco-friendly as white reflective paint or Orca film.
• Even though good Mylar isn't that expensive, it can be pricier than reflective paint or emergency blankets, especially for bigger grow rooms.
• When air from fans or ventilation systems gets mylar to move, it can be noisy in certain setups. 
• Thinner versions of Mylar may allow some light to pass through if not backed by something solid, thus reducing effectiveness.

Reflective Materials to Avoid in the Grow Room

Not everything that glitters is gold, and the same applies to reflective materials. While some materials work wonders in bouncing light back to your plants, others can do more harm than good. 

Here are two materials you might come across online but should steer clear of when setting up your grow room.

• Styrofoam

Sure, styrofoam has a decent reflectivity range of 75–85%, which is why filmmakers sometimes use it for indirect lighting. But in your grow room? It's a disaster waiting to happen.

The biggest red flag? It's highly flammable. With grow lights blazing and electrical systems running, styrofoam can easily ignite from a single spark. Do you really want to risk turning your grow room into a fire hazard? Yeah, didn't think so.

• Mirrors

At first glance, mirrors might seem like the perfect reflective material. After all, they bounce back clear images, right? But here's the catch: mirrors don't reflect light in a way that benefits your plants.

Instead of evenly distributing light, mirrors scatter it in weird patterns and create hot spots. These concentrated light and heat patches can burn your plant's leaves — definitely not what you're going for.

Key Factors to Consider When Choosing Reflective Materials for Your Grow Room

1. Light Reflection Efficiency

One of the most important factors in cannabis cultivation is light reflection efficiency, or how well your plants can make use of the light available to them. Unlike growing outdoors where there's abundant light, it's always a limiting factor indoors, so growers are forced to use artificial grow lights.

But since these grow lights cannot be as powerful as the Sun, you must do everything to maximize their efficiency, which includes using reflective materials to bounce the light of your walls, floors, and ceilings back at the plants to ensure that they are all getting an even amount of light.

High light reflectivity matters a lot simply because of the way plants function. As you may already know, cannabis plants need light for photosynthesis which provides fuel for it to grow well. However, artificial grow lights cannot be as intense as natural light, and most of it is wasted too. But, if you can redirect light hitting the walls and other surfaces of the grow room back to the plants effectively, it has incredible benefits. 

For one, more light helps plants produce more energy for growing, flowering, and trichomes. Also, when all parts of the plant get uniform light, weak spots are avoided, thus improving the quality and quantity of the harvest.

Now energy efficiency simply involves making the best use of light you have so that you don't need to add more lights. This also saves electricity, so when you look for reflective materials, look for ones that reflect at least 85-95% of the light. 

Out of most materials you get, Mylar can reflect light up to 98%, making it a popular choice among growers. It redirects light very effectively is easy to install and quite lightweight in nature. On the other hand, flat white paint isn't as reflective; however, it does reflect between 85-90%. It's cheaper and easy to apply. The Panda film is a good choice too as it serves a dual purpose with a white reflective side that reflects light and has 85-95% reflectivity.

2. Durability and Maintenance

Durability is an important factor to consider when choosing reflective materials for your grow room.

The environment in your grow room is dynamic and complex, with too much humidity, temperature fluctuations, and frequent handling and/or movement. Thus, the materials you use to reflect light must be able to ensure these conditions without compromising on how they perform over a period of time.

You may encounter several issues when it comes to reflective materials in the grow room. For instance, high levels of humidity can ruin materials or cause them to warp. Also, they can grow mold just like other materials do when they are exposed to high levels of humidity for a long period of time. 

Also, as grow lights emit more heat, materials that cannot endure heat can crack, start peeling, or lose their reflectivity.

In addition, don't forget that you'll be handling them regularly even if you're just tending to the plants. Whether you're pruning, watering, and raising or lowering lights, you may brush against these reflective materials, which means they should be okay with constant handling. 

For this reason, choose materials that are meant for the environment in your grow room. Most commercial grow tents use industrial materials so you can expect good quality (assuming you've done your research and purchased from a trusted manufacturer). But, if you're planning to construct a DIY grow tent and install the reflective material yourself, you should choose materials that can endure stress in the grow room environment. 

Keep in mind that in areas with high moisture, absorbent materials may develop mold or algae. Use non-porous materials and ensure adequate ventilation to avoid these.

Also, sometimes your material can tear, peel, or just rip apart with time. Never use sharp tools or abrasive cleaning methods, which can damage the surface. Remember that you should repair the damaged parts or replace them immediately to ensure they are consistent. 

Apart from that, you should pick grow room-specific materials that are engineered to resist moisture, heat, and physical stress. 

Make sure all materials are fastened down and there are no loose edges that could snag or tear.

3. Cost and Availability

When you're setting up a cannabis grow room, you'll be concerned about everything including the availability and cost of the reflective materials. For instance, you might like one type of material a lot more than the others, but what if it's super expensive? Therefore, to make a grow room setup successful, you must balance the efficiency, price, and tastefulness of the setup.

For instance, Mylar is one of the best materials because of its high reflectivity of around 98% which helps with light efficiency. But, it is usually quite costly, especially if you choose the thicker varieties (2 mil or 4 mil).

Secondly, Panda Film is useful too, and compared to Mylar it offers more value for your money since it's not as expensive. 

But, you can also get a flat white latex paint as a budget-friendly alternative that reflects about 85-90% of sunlight and is cost-effective. This is a good choice for those looking for a long-lasting and low-maintenance option.

If you have a very limited budget, plastic sheeting can be quite effective. Plastic coverings are easy to buy and install by most kinds of growers. However, such white tarps will not provide sufficient durability or efficiency. The same goes for aluminum foil. Although it's cheap, it has low reflectivity and can cause hot spots, so it's not very effective.

4. Heat Management

Maintaining the proper temperature in a cannabis grow room is very important as sudden fluctuations can harm the plant. The reflective material you choose will not only alter the light distribution but also influence the absorption, reflection, and retention of heat. 

Various reflective materials reflect light differently, and the same applies to managing heat as well. For example, materials like Mylar do not absorb light and heat. As a result, a lot of the light energy reaches the plants without increasing the room temperature. 

However, other materials can trap heat and cause hot spots. Hot spots are areas where a lot of light and heat can gather, and burn and damage the leaves of plants, or cause uneven growth. They often occur with reflective surfaces with imperfections, like a crinkly aluminum foil or shoddily installed Mylar.

To prevent hot spots, make sure reflective items are adequately attached to one another to spread light. Choose materials like Panda film that diffuse light well and spread it out evenly across the grow room instead of creating hot spots.

Some Tips for Using Reflective Materials Effectively

No matter which material you use, a few key things can make all the difference. Use these tips to avoid common mistakes and ensure your grow room is maximizing light without affecting your plant.

1. Smooth Surfaces Are Ideal

Avoid creases, wrinkles, and bubbles when applying your reflective material. These imperfections can create an uneven light distribution, resulting in bright or dark spots that aren't ideal for your plants. Plus, misdirected light means wasted energy. 

2. Cover Every Inch

Don't stop at the walls. Make sure to cover doors, windows, and any other openings to keep light from escaping. Even the smallest light leak can add up over time, so seal those corners and edges like a pro.

3. Use a Lux Meter

Want to know how much light your plants are actually getting? Invest in a lux meter. It's a handy tool that measures light intensity in specific spots, helping you identify and correct any weak areas in your setup.

4. Keep It Clean

Reflective materials lose their reflectivity when they're dirty or discolored. Regular maintenance is a must — give them a quick wipe-down with isopropyl alcohol or hydrogen peroxide to keep grime, mold, or discoloration at bay. 

5. Choose the Right Material for Your Space

Different materials have different perks, especially when it comes to managing heat. For cold grow rooms, use materials like Mylar, emergency blankets, orca film, or panda film. These reflect both light and heat to keep things cozy.

For hot grow rooms, stick to flat white paint. It reflects light without trapping too much heat, keeping your plants cool and happy. In any case, it's best to give temperature a check after installing reflective material to avoid any surprises. 

By paying attention to these details, you'll make the most of your reflective materials — and your grow lights! 

Summary: Reflective Materials to Use In Your Grow Room

Maximizing light efficiency in your grow room isn't rocket science, but it does take some thoughtful planning. By choosing the right reflective materials, avoiding common pitfalls, and keeping your setup clean and well-maintained, you'll create an environment where every ray of light counts. 

Whether you're on a budget or splurging for premium options, the result is the same: healthier plants, better growth, and more abundant yields. After all, when it comes to growing cannabis, light isn't just a resource — it's the lifeblood of your garden. Let's not let it go to waste.