7 Best Greenhouse Covers for Increased Light
Boost light in shady greenhouses with reflective covers. These materials diffuse sunlight, maximizing plant growth in low-light spots. We review the top 7.
We’ve all been there: the perfect spot for a small greenhouse is tucked away behind the barn or shaded by that big oak tree for half the day. While it protects the structure from wind, it starves your plants of the full, direct sunlight they crave. The good news is you don’t have to move the whole setup; you just need to get smarter about the light you do have. By lining your greenhouse with the right reflective material, you can bounce and scatter precious light into every corner, turning a dim space into a productive one.
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Maximizing Light in Your Shaded Greenhouse
The core challenge in a shaded greenhouse isn’t just the lower light levels, but the unevenness of it. One side might get a blast of morning sun while the other stays in shadow, leading to lopsided growth. Reflective covers solve this by capturing that available light and redirecting it back onto your plants from multiple angles.
Think of it as creating an environment of ambient light rather than relying on a single, direct source. This not only boosts the total light your plants receive but also ensures it reaches the lower leaves that are often shaded by the upper canopy. The goal isn’t just to make it brighter, but to make the light more usable.
When choosing a material, you’re balancing a few key factors.
- Reflectivity: How much light does it actually bounce back? Mylar is king here.
- Diffusion: Does it scatter light evenly or create a mirror-like reflection? Diffuse light is generally better as it prevents "hotspots" that can scorch leaves.
- Durability: Will it stand up to moisture, temperature swings, and the occasional bump from a tool handle?
- Installation: How easy is it to put up and will it stay put?
There’s no single "best" option. The right choice depends on whether your priority is raw power, even distribution, insulation, or simply your budget.
VIVOSUN Mylar Film: Top All-Around Performer
If your primary goal is maximum light reflection, standard Mylar film is hard to beat. VIVOSUN is a common brand that offers a highly reflective, mirror-like surface designed to bounce back over 95% of the light that hits it. This is a massive boost for any light-starved corner of your greenhouse.
The material itself is a thin polyester film, making it lightweight and easy to cut to size with scissors. You can staple it to wooden frames or use a specialty tape to attach it to poly walls. Its effectiveness is undeniable; you will immediately notice a significant increase in ambient brightness.
The main tradeoff with this high-specular film is the risk of creating hotspots. Because it reflects light like a mirror, a direct beam of sun hitting the Mylar can be focused onto a small area of a plant, potentially burning the leaves. To avoid this, try to crinkle the film slightly during installation or ensure it’s positioned to reflect light generally, not from a direct, intense source.
B-Air Panda Film for Heavy-Duty Light Reflection
Panda Film is the workhorse of greenhouse liners. This thick, durable polyethylene film is black on one side and a highly reflective white on the other. It’s completely light-proof, which gives it a dual purpose that simple Mylar can’t match.
The white side offers excellent, diffuse reflection. It’s not as intensely reflective as Mylar, but its matte surface scatters light softly and evenly, which is exactly what you want for gentle, full-plant illumination. The black side is perfect for blocking out unwanted light, making it ideal for dividing a greenhouse into different light zones or for laying on the floor (white side up) to reflect light upwards while also suppressing weeds.
Its real strength is its durability. Panda Film is tear-resistant and waterproof, holding up to the daily rigors of a working greenhouse far better than thin Mylar. This is the material you want for floors, partitions, or any high-traffic wall where you need both reflection and resilience.
Reflectix Insulation for Both Light and Heat
For anyone growing in a climate with cool shoulder seasons or cold nights, Reflectix is a game-changer. This material consists of a layer of bubble insulation sandwiched between two layers of highly reflective film. It addresses two problems at once: low light and temperature fluctuation.
While its primary job is insulation, the reflective surface does an excellent job of bouncing light around the greenhouse. It’s not quite as efficient as pure Mylar, but the difference is minimal for most hobby applications. The real benefit is the thermal barrier it creates. Lining the north wall of your greenhouse with Reflectix will not only brighten that shady side but will also significantly reduce heat loss overnight.
This two-for-one functionality makes it a very practical investment. You get a brighter space during the day and a more stable, warmer environment at night, extending your growing season on both ends. The initial cost is higher than a simple film, but you’re getting an insulation product and a light reflector in a single, easy-to-install package.
Growers Solution Aluminet for Diffused Light
Aluminet is a bit of an outlier, as it’s technically a shade cloth. But its unique, knitted aluminum screen construction makes it a fantastic tool for managing light in tricky situations. It reflects sunlight and heat, but because it’s a mesh, it also allows for air circulation.
Protect your plants and outdoor spaces with this durable 55% shade cloth. Made from high-density polyethylene, it provides essential sun protection while allowing airflow and easy installation with included grommets.
In a shaded greenhouse, you might think shade cloth is the last thing you need. However, consider a spot that’s in deep shade most of the day but gets blasted with intense, direct sun for two hours in the afternoon. Aluminet can be used to temper that harsh period, preventing scorch, while its reflective properties scatter that intense light more evenly throughout the space.
Think of it less as a wall liner and more as a strategic curtain. You can hang it internally to protect sensitive plants from a sudden burst of sun or to diffuse light from the sunniest wall to the darkest corners. It’s a tool for light management, not just reflection, offering a level of control that solid films can’t provide.
FarmTek White Poly Film: A Budget-Friendly Fix
Sometimes, the best solution is the simplest and most affordable one. Standard white greenhouse poly film is an excellent, budget-friendly option for increasing ambient light. While it lacks the high-tech reflectivity of Mylar, its white surface provides fantastic light diffusion.
This is a key point: high reflection isn’t always better than good diffusion. A white poly wall won’t create mirror-like hotspots. Instead, it scatters light gently and evenly, providing a soft, usable glow that benefits the entire plant. It’s a reliable way to brighten up a space without any risk of damaging your crops.
Because it’s sold in large rolls and is relatively inexpensive, white poly is the ideal choice for lining the entire interior of a hoop house or covering a large wall. It’s durable, waterproof, and easy to clean. It may not be the highest-performing option in terms of raw numbers, but its practicality and cost-effectiveness make it a go-to for many small-scale growers.
iPower Adhesive Mylar for Easy Installation
One of the biggest hurdles with any greenhouse project is the time and effort of installation. Adhesive-backed Mylar, like the kind offered by iPower, directly addresses this problem. It’s essentially a giant, highly reflective sticker.
The convenience factor here is huge. Instead of messing with staples, glue, or tape, you simply clean your surface, peel off the backing, and smooth it on. This makes it perfect for lining solid surfaces like plywood, drywall, or even smooth plastic panels. It creates a clean, seamless reflective wall with minimal fuss.
The tradeoff is cost and surface preparation. You’ll pay a premium for the adhesive backing, and it requires a non-porous, clean surface to adhere properly. It won’t stick well to rough wood or the inside of a flexible poly tunnel. But for a permanent installation in a greenhouse with solid walls, the time saved can easily justify the extra expense.
TerraBloom Diamond Mylar for Maximum Diffusion
If you want the best of both worlds—high reflectivity and excellent diffusion—diamond-textured Mylar is the answer. This film has the same high-reflectivity base as standard Mylar, but its surface is embossed with a pattern of small, diamond-shaped facets.
This texture is the key. Each tiny facet reflects light at a slightly different angle, scattering the light rays in thousands of different directions. The result is an incredibly even, intense ambient light that penetrates deep into the plant canopy without creating any hotspots. It effectively combines the power of Mylar with the gentle, even light of white poly.
This is a premium product for growers who want to optimize every last photon of light. It’s particularly effective at illuminating the lower and middle sections of tall plants like tomatoes or cucumbers. For a shady greenhouse where you need to make the absolute most of limited light, diamond Mylar provides the most efficient and plant-safe reflection available.
Ultimately, the best reflective cover is the one that solves your specific problem. Don’t just chase the highest reflectivity number; consider whether you need insulation, durability, diffusion, or ease of installation. Take a hard look at your shaded space, identify its biggest weakness, and choose the material that turns that liability into an asset for your plants.
