- Shining a Light on Reflective Materials
- Managing Light in a Grow Room
- Light Reflective Materials for Grow Rooms
- Additional Grow Room Reflective Material Tips
- Gardening With Foil: How To Recycle Tin Foil In The Garden
- Aluminum Foil Gardening
- Reflective materials for indoor grow rooms
- White paint
- Black and white Polymer
- Emergency blanket
- Aluminum foil
- Blackout canvas
- White bed sheet
- Orca film
Shining a Light on Reflective Materials
Creating abundance is one definition of gardening, a slight of hand accomplishment that enlists the power of nature to help make plants grow faster and produce better yields.
Bringing a garden indoors sheds light on just how important illumination is to this process. Good lighting is critical, and what seems so natural and effortless outdoors can be difficult to duplicate within four walls.
Providing supplemental lighting is one of the first concerns of any indoor gardener, whether that involves opening the drapes to shine some light on a houseplant or setting up a large grow tent that will house multiple mature plants.
Making lighting choices comes from understanding how plants use specific wavelengths of the light spectrum during different stages of growth (PAR).
It also helps to know how to fully utilize the intensity of different light technologies while minimizing potential disadvantages like high energy consumption and heat buildup.
Managing Light in a Grow Room
Multiple factors contribute to the development of an effective strategy for good light management beyond choosing a particular type of light technology.
One good example is the use of a reflector hood to divert light that would otherwise be wasted illuminating the ceiling. The hood reflects light back down onto the plants where it can increase light efficiency by 40%, or even more if the patterns of reflection overlap across multiple fixtures and reflectors.
Reflector hoods aren’t the only options when taking advantage of redirected light energy. Light reflected from a number of locations, not just from one or a series of overhead fixtures, helps approximate the diffuse lighting conditions in an outdoor garden. It’s an over, under, around and through approach to comprehensive, distributed illumination, and one that can mediate problems that arise when using focused light.
To get the best use of illumination, indoor gardeners place lights directly above plants and as close as possible without burning them. This maximizes the intensity of the light hitting plant leaves, and takes advantage of the inverse square law, which for our purposes states that light energy decreases the farther you move from the source of illumination. When plants are small, there’s no problem with this approach.
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Seedlings are bathed in light, convert that light to food and grow big and strong, with the topmost growth getting the most intense energy. As those top leaves develop faster than the leaves beneath them, they create a canopy that blocks light from lower leaves and smaller plants.
The diffuse light that pervades an outdoor garden and provides energy to the undergrowth, resulting in balanced plant development, is either absent in an indoor growing environment, leading to spindly plants and other growing problems, or is provided through some other means.
This can be accomplished using side-mounted lights, but using reflective materials instead can reclaim light energy without the use of additional expensive fixtures, their increased energy costs and at least some of their freight of potential heat problems.
Using reflection to maximize light encourages many indoor gardeners to invest in dedicated growrooms and enclosures like grow tents that include light reflective walls, ceilings and floors.
Light Reflective Materials for Grow Rooms
Many materials reflect light and can be used to redirect light energy onto plants in a grow space or grow room. Some are more effective than others, and a few have been developed especially for horticultural applications.
For example, some embossed reflective surfaces designed for indoor gardens bounce light using faceted diamond, hammered or other dimensional textures for more diffuse coverage and less risk of creating hot spots—inadvertently focused light energy that can burn plants.
This is distinct from specular or flat reflective surfaces that need to be smooth and clean to remain effective. By some estimates, reflective materials working in concert with an efficient set-up where plants are carefully spaced can increase light efficiency by up to 30%.
There are lots of reflective materials on the market, from the metals in reflector hoods, to films, non-woven fibrous sheets and paints. Let’s take a look at a few different options to see how they shine:
Aluminum Foil – A popular do-it-yourself choice, aluminum foil isn’t a particularly effective reflector, even though it can produce an impressive amount of glare. Generally considered 50-55% reflective, that number drops drastically when the surface deforms, which can happen easily, producing hot spots.
Mirrors – If you’ve thought of using aluminum foil to reflect light onto your plants, the notion of employing a mirror probably wasn’t far behind. Depending on the backing materials involved (aluminum silver, gold), mirrors absorb some light wavelengths, while having the potential of disrupting the wavelengths plants need most.
They create dangerous hot spots, too. Almost as bad, mirrors are notoriously susceptible to delamination in moist conditions, so, after you realized the mirror is hurting your plants, you’ll discover you’ve ruined your mirror, too. There’s a good reason you don’t see mirrors in grow boxes or tents.
White or Light Paint – You may have noticed plants situated next to a white or light-colored outdoor garden wall grow faster than other like plants in the landscape. This is due to the power of reflected light energy in action.
A simple, light-colored paint can help increase the available light to indoor plants, too. Paint is inexpensive, readily available and easy to use. When kept clean, it is also one of the most reliable light reflective surfaces around. Flat, bright white paint from any local home improvement store will be 75% reflective or more.
Some reports place that figure at closer to 90%. It may seem counter intuitive, but glossy paint will not reflect as well as flat paint, so keep that part simple. It’s also worth noting that a smooth wall will reflect light more evenly than one with imperfections.
Oh, and save yourself the hassle of prepping bare surfaces by purchasing a paint and primer in one product. While perusing paint labels, you might also consider a paint that contains a mold control additive that can help limit the development of mildews, molds and fungi in wet or humid locations like floors, tabletops and benches.
Mylar – Mylar is the brand name of a variety of chemically stable polyester film that can be highly reflective. Think shiny Mylar balloons and you have the general idea. This material is also referred to as BoPET, short for its technical description: biaxially oriented polyethylene terephthalate.
Mylar can be up to 97% reflective, and is available in thicknesses of 1 mm and 2 mm, and in smooth and textured finishes. It is popular for use in grow tents, where this extruded and stretched product is bonded to the interior walls, ceiling and floor, while a thick canvas fabric is used for the outer shell. Mylar is also sold in rolls. It has the advantages of being effective and flexible.
Mylar reflects heat and may retain moisture long enough for it to become a problem. The 1-mm sheets can be fragile, and it may lose effectiveness over time through the action of moisture, dust and dirt accumulation and the transfer of body oils through physical contact.
Smooth Mylar sheets are known for producing hot spots, especially when scratched, creased or otherwise deformed. Most experts recommend paying a little more for patterned Mylar because it reduces instances of hot spots and broadcasts light the best.
Foylon – Possessing many of the same characteristics of Mylar, Foylon is a laminate made of spun polyester fabric and aluminum. It is widely considered more rugged and durable than Mylar and has a reflectivity of 95%.
Foylon is tear resistant, which makes it relatively easy to position, clean, reposition and maintain. Like Mylar, Foylon also reflects heat, and using it may require increasing the ventilation in an enclosed space.
Black and White Polymer – This synthetic poly film is white on the front and black on the back. In part, this is to help block exterior light and maintain photoperiod integrity. Poly has a 90% reflectivity rating. It is also waterproof and algae, mold and mildew resistant. Poly is often recommended for DIY projects because it’s durable and easy to work with. For heavy-duty applications, consider the thicker 6-mm rolls.
Reflective Microfiber – This fabric product has up to 94% reflectivity and excellent diffusion thanks to the scatter pattern produced by the millions of compressed fibers on its surface. It isn’t as critical to maintain a smooth wall or other surface when using reflective microfiber fabric because this product’s enhanced diffusion features make hot spots less of an issue.
Reflective microfiber is also tear resistant, mold resistant and easy to clean. Although it has a black, light-blocking exterior surface like poly film, it is a very different product, with better diffusion and reflectivity.
Additional Grow Room Reflective Material Tips
There are a couple of other things to consider when adding a reflective material to your grow space. Reflected light is most effective in close proximity to plants. This is one time when “roomy” isn’t an advantage. If the airflow is good, the closer the plants are to the reflective material, the more they’ll benefit. Remember the inverse square law.
Installation planning is another important consideration. Reflective films like Mylar should hang smooth and wrinkle free. Ripples and wrinkles are what cause hot spots, and even minor imperfections like scratches and small tears can have negative consequences. If you’re looking for an easier way to install these types of materials, try using adhesive hook-and-loop tape.
Once the tape is mounted, adding the panels in a way that will produce a smooth finish is easier, and incurs less risk of accidentally tearing the film than using staples, glue, tacks or nails. If you’re careful, this option also has the advantage of allowing you to more easily re-position panels or remove and install them in another location later.
Gardening With Foil: How To Recycle Tin Foil In The Garden
Earth conscious or eco-friendly gardeners are always coming up with new clever ways to reuse and recycle common household trash. Plastic bottles and jugs are being repurposed as drip irrigation systems, flower pots, watering cans, birdfeeders, and other brilliant things, finding a new life in the garden, rather than filling up landfills.
Cardboard toilet paper rolls now serve their purpose in the bathroom then go on to a second life of cradling little seeds as they germinate. Even broken dishes, mirrors, etc. can find a new home in the garden when crafted into mosaic stepping stones, pots, birdbaths or gazing balls. You can even recycle tin foil in the garden! Read more about uses for aluminum foil in the garden.
Aluminum Foil Gardening
There are many benefits to using aluminum foil in the garden. It can deter pests, increase plant vigor, retain soil moisture, and help warm or cool the soil. However, before reusing aluminum foil, you should wash off any food remnants thoroughly and smooth and flatten out the pieces as much as possible. Even ripped or small pieces can serve a purpose, but dirty aluminum foil may attract unwanted pests.
Seed Gardening with Foil
Start collecting aluminum foil from your winter holiday feasts to reuse for seedlings in early spring. Large reusable pieces of tin foil can be wrapped around cardboard or used to line cardboard boxes to make light refracting boxes for seedlings. As sun or artificial light bounce off the aluminum foil, it increases light to all parts of the seedlings, creating full plants instead of leggy, spindly ones.
The refracted light also helps to warm the soil, which will help seed germination for many types of plants. Cold frames can also be lined with aluminum foil. Smaller pieces of foil can be used to wrap cardboard toilet paper tubes that are repurposed into seed pots. The aluminum foil prevents the cardboard tubes from falling apart when they get wet.
How to Recycle Tin Foil in the Garden
The uses for aluminum foil in the garden go far beyond just seed care. Recycled tin foil in the garden has actually been a pest deterring hack for ages.
Like me, you may have seen trees with aluminum foil wrapped near their base but never really questioned it. For many gardeners, this is a common practice to deter deer, rabbit, voles or other rodents that may chew on the tree in winter when fresh greens are scarce. Foil can also be wrapped around the base of evergreens or shrubs to prevent them from becoming the winter buffet.
Fruit growers also use strips of aluminum foil in the garden to hang in fruit trees to scare away birds that may eat blossoms and fruit. Strips of foil can also be hung in vegetable gardens or berry patches to deter birds.
When placed around the base of plants, aluminum foil refracts light up into the plant from the ground. This helps cool the soil around plants, allowing it to retain more moisture. It also increases photosynthesis and, therefore, plant vigor. In addition, it lights up the undersides of the plant where destructive pests like aphids, slugs, snails, etc. like to hide.
If you do not like the look of patches of aluminum foil in the garden, shredded aluminum foil can be mixed in with mulch and placed around the base of plants. While many insects dislike the reflective surface of aluminum foil, butterflies and moths will appreciate it. The refracted light of foil can help butterflies dry out their wings on dewy mornings.
Foil can also be placed on the inside or outside of plant containers to catch water or keep soil in.
Reflective materials for indoor grow rooms
When you are growing cannabis indoors you are creating a self enclosed environment by providing ventilation, lights as well as soil and nutrients that promote plant growth. Usually grow lights are the single most expensive thing any grow room needs and that is because light is cannabis plants main energy source and without proper light there will be no growth and no bud production. Over the years HID light have become very efficient as well as cheap and there have even been some newcomers like fluorescent light and LED diode lights that can grow cannabis plants. But what if I told you that you can get up to 30% more light from your existing light source without the need to install new lights and without more electricity costs? If you are intrigued then you are not alone because many growers when first starting out find information about grow room reflectivity and are pleasantly surprised when installing a reflective film or painting you grow room white can increase the overall growth and yield of your plants growing in that room.
When autoflower plants are growing outdoors then they get as much sunlight as they need and it does not matter if they are a few centimeters closer to a light source and if the surrounding environment reflects light. But indoors when growing with artificial light sources every centimeter of distance between a light source and your plants will count and in your grow closet or tent is not reflective some light will be absorbed by those walls and turned into heat but that obviously is not efficient. That is why growers usually use various reflective materials to reflect all that light back to their plants and to create the most growth possible from their artificial light sources.
Here is a list of all the possible reflective materials that you can use in your grow room. Usually it depends on your growing conditions and your budget what materials will you be able to use but most of these will reflect light better than nothing and that is a start!
Mylar is maybe the most common grow room reflective material that usually comes in 1 mm or 2 mm thick sheets and reflects more than 95% of the light that hits that surface. This material is fairly inexpensive and it comes either in flat roll form or pre-made sheets that you can stick to your walls. There are various versions of this material that you can get but the best ones are those that have some kind of a texture that will help with light reflection and will stop wrinkles from forming. Regular mylar sheets are usually very fragile and any damage to them can result in bends and folds that tend to concentrate light in one spot and if that happens near your plant then it can get heat damage.
- Foylon – Foylon is a more durable version of mylar that has a reinforced laminate coating and will not tear or crease that easily. Foylon is a bit more expensive than regular mylar but it can be used multiple times and if you manage to make it dirty you can simply clean it without creating folds or bends.
C3 anti-detection film – This is another variant of Mylar and it is a material that has been specially designed not to let any heat trough and because of that it can be a great addition to grow rooms that are constructed in cold climates. But you have to be careful in hot climates where you will need a lot more ventilation to counteract that heat as well as those light reflection properties.
The single most inexpensive and easiest method how to create a great reflection surface is to get a flat white paint with as much titanium oxide as you can find. White paint is used in larger as well as smaller growing spaces and it can reflect up to 80% of the incoming light and for such a cheap price it is a great solution. If you are using white paint make sure that it also has additives for mold resistance as that will ensure your grow room will stay sterile and no molds or mildew will form on your walls and on your plants. And before you apply that paint to all the walls I would also advise to first get a white mold resistant primer to cover all those surfaces as that will allow you to create another protective layer as well as will increase your paints reflectivity rating.
- Elestomere paint – And another great substitute for simple flat paint is elestomeric paint that has a latex additive that makes it a semi liquid and will allow paint coating to seep into all cracks and even heal itself under pressure and some other mild damages. This paint can also reflect a great deal of light but it will be a bit more expensive and you will need to wait a longer time for it to dry off.
Black and white Polymer
The black and white polymer sheets that are also called panda plastic or panda foil is a plastic polymer with one side black but the other side white and this can be a great tool for your gardens light and heat isolation and reflectivity. Panda plastic wraps come in rolls and you can staple or glue them to any surfaces you want but they tent to be on the expensive side and if you get them too close to your light source they can easily melt. This option can be great for large scale sealed grow operations but for small scale cabinet grows it usually is an overkill and it is too hard to properly attach this polymer to all the walls without cutting it in multiple places.
Emergency blankets are those foil like things that we all have seen in movies when ambulance workers wrap people in when they have been in cold water or stayed out in cold wether too long. These things are very cheap and they are made from mylar but they tend to be folded up into small packages and they are not completely lightproof because of the thin material. These things can be a great to use for temporary grow operations that you will eventually tear down as they are inexpensive and will get bent and folded anyway so you will have to remove them each time you start a new grow.
Aluminum foil that we also know as thin foil is a common household appliance that we use for cooking and other stuff. Despite that this material looks very shiny it does reflect only about 60% of the light that comes in contact with the dull side and the shiny side is even less reflective. This foil looks like a great way how to reflect the light but it really is not a great option because this foil tend to wrinkle and crease a lot and all those wrinkles and folds will create uneven light distribution that can even burn your plants. Use thin foil only if you have no other alternatives.
Blackout canvas is a product that is used in top of the line grow tents as this is maybe the best material that completely reflects all the light back in your growing environment and does not let any light to leak trough this material This blackout canvas is one of the most expensive reflective materials but if you need to completely light seal your grow environment then this is the way to go and because it is made from non-toxic materials it will not react with your grow lights or the air inside your room.
White bed sheet
If you have no other option then you can also line your grow room walls with white bedsheets as they are quite reflective and easy to work with. That is why many growers have used this material to line their cabinet grow boxes as well as larger grow environments. But because these materials are not 100% lightproof they will let light trough and for some that is not acceptable.
Styrofoam that is also known as polystyrene foam sheets is a great and cheap way to reflect some of the light back to your cannabis plants. These styrofoam sheets can be bought in bulk and are very light so you will be able to hang them to your walls but be careful and not put them too close to your grow lights because they cam melt easily and cause fire hazards. You can expect up to 70% reflection but usually these are just temporary solutions while you can get something much more reflective.
Orca grow film is a special material created for complete light reflection and diffusion and in most cases it works better than regular mylar or any other reflective material. Orca film has a snowflake like molecular structure that scatters the light to all sides and that does not create hot spots and this material also does not let light trough. When installing this material you have to put the white side inwards and the black side outwards so that the light is reflected back to your autoflowers. And another great thing about orca film is that it has also some anti-mold properties and the company states that it can reflect up to 95% of the visible light spectrum! But the only drawback is price because this material is very expensive and for the beginner grower that is on a budget it can be too expensive!
When talking about reflective materials I also need to say a few words about various grow light reflectors that will direct the light from that light source downwards. With these reflectors when combining them with reflective materials on all your walls you can ultimately create around 30 to 50% more light directed to your plants and that can be a huge deal as you will not need to increase your grow light count or strength but will create more growth and bud production.