Building your own greenhouse is not only a great idea for a home project, it’s also a great way to encourage a sustainable, eco-friendly lifestyle. A greenhouse allows crops, flowers, and other plants to grow by creating an environment where heat and humidity can be maintained. Many plants can only grow in warm weather, but a greenhouse allows for growth all year long - as long as they’re properly sealed to keep that warmth and temperature consistency inside.
Many people are interested in building a quality greenhouse that’s budget-friendly. Because fiberglass and glass-walled greenhouses aren’t exactly affordable, there are other methods you can use to keep whatever you’re growing safe and warm - without breaking the bank. This article will act as a guide and help you through the process of choosing what type of plastic is best to use for your specific greenhouse. It’s a big undertaking, so we’re here to break things down.
How to Choose Greenhouse Plastic
When you’re building a greenhouse, any old plastic won’t do the trick. There are a few considerations to keep in mind when you go about making the decision, and here are the most important factors:
The material that protects your greenhouse will be constantly exposed to the elements - heavy rains, strong wind, and snowfall can have a big impact on its integrity. Even direct sunlight is not a friend to all plastics, as many plastics can turn brittle after lengthy exposure to UV light.
One single tear on your greenhouse plastic can reduce its effectiveness, so we recommend investing in a high-quality plastic that will stand the test of time. Choosing a plastic that’s made with strong material will save you from constantly spending money on repairs for your greenhouse. Invest once instead of over and over again.
Modern greenhouses have seen improved results by using transparent materials - many find that clearer is better when choosing the plastic that surrounds your greenhouse. Sunlight should be able to reach the plants inside your greenhouse so that they can go through the process of photosynthesis. The goal isn’t necessarily to get as much sunlight as possible into your greenhouse - it’s about finding the balance.
Finding the right balance between thickness and transparency is key when choosing the right plastic for your greenhouse covering. Some plants need enough sunlight to keep them alive, but not too much that they’ll dry out or burn. Other plants need as much as they can get. It all depends on what type of vegetation that you’re growing.
It’s true that a thick sheet of plastic is strong, but it also gets heavier with added thickness. A sheet of plastic is incapable of offering structural integrity, which means that the weight from that added thickness will depend on the frame of the greenhouse to hold it up. While it’s not a bad thing to have heavy plastic, you must make sure that the frame of your greenhouse is sturdy enough to uphold it.
Anti-Condensation & Anti-Dust
Depending on the climate where you live, there are a few factors that can reduce how effective your greenhouse is. When days are cold, the difference between the cold outside and the warm inside of your greenhouse will create condensation on the inner layer of your plastic sheet. This condensation could then fall onto your plants, which will disturb the ecosystem that you’ve put so much effort into creating by encouraging the growth of mildew.
Certain plastics are equipped to keep this condensation drip from happening - the condensation runs off the side of the greenhouse to meet the ground instead of disturbing the delicate ecosystem that the plants are thriving in. There are also some plastics that discourage condensates from dripping onto the plants and instead retain them on the surface of the plastic so they can evaporate back into the atmosphere naturally.
Though condensation issues can be a hassle, dust buildup is an even bigger problem. Dust reduces the transparency of your plastic sheeting - so you want to avoid certain plastics that retain excess charge on their surface, because this makes it extremely easy for dust to accumulate on the panels of your greenhouse.
Types of Greenhouse Plastics
At Farm Plastic Supply, we offer four main types of quality plastics that allow your greenhouse to cultivate and grow what’s inside the best that it can. The plastics we offer are: 4 Year Clear, 4 Year White, IRAC, and CoolMax. Here’s the rundown on these four plastics:
4 Year Clear
4 Year Clear is the basic, standard version of greenhouse plastics. It lets light through in a manner that’s almost unobstructed, so transparency is not a problem with this type. It has a 4-year UV life, meaning that it will uphold its integrity for four years without needing to be replaced due to fading or cracking.
If light transmission and durability are important to you, then 4 Year Clear is the way to go. Manufacturing of this type of plastic takes no shortcuts at Farm Plastic Supply, and when we say it’s 6 mil, it’s 6 mil! It’s not a rounded-up approximation of 6 mil like others may sell.
4 Year Clear is excellent when it comes to germination and growth promotion, and is especially useful in areas with high UV transmission, since we use the best UV protection around - protection that maintains a longer film life, blocks harmful UV rays, and protects your plants. But even though this type of plastic blocks the harmful UV rays, it promises optimum light transmission at over 90%.
This type of plastic also does well under the most inclement of weather conditions, as it can withstand anything from torrential rain to heavy snowfall and anything in between. It’s infused with special resins to keep it flexible in cold conditions and stable in hot conditions. This type of plastic also attracts less dust and is extremely easy to clean.
4 Year White
4 Year White blocks about half the sunlight and diffuses it so your plants don’t burn. Like 4 Year Clear, it offers 4-year UV life. This is a great type of plastic to choose if you’re looking to spread out the sunlight and reduce direct exposure on your plants.
White plastic sheeting is known for keeping a consistent temperature inside the greenhouse, which is essential in protecting your plants. This type of covering also protects plants from harmful wind damage. We offer nearly every size of 4 Year White, and we also will cut to the length of your greenhouse specifically.
IRAC Greenhouse Plastic
IRAC contains infrared additives in order to keep heat in, along with anti-condensate additives to keep condensation from dripping down onto your plants. Instead, this additive allows the droplets to run down the film to the edge where they can drip safely.
This type of film is also called a thermal film because, unlike a standard film that allows the energy from sunlight to radiate out, IR film traps it and raises the overall temperature of the greenhouse to help your plants thrive. This is especially great for plants that need very warm environments in order to grow correctly.
This type of sheeting also diffuses sunlight in the same manner of a clear poly sheet. Translucent film will do this as well, but IRAC does light transmission more effectively because of its thermal qualities.
As previously mentioned IRAC is also an anti-condensation covering. Condensation can be a problem for greenhouses as it reduces light transmission and encourages the spreading of disease within the plant life of a greenhouse. Anti-condensation films help condensate to flow down the plastic and prevent droplets from forming and harming the plants.
CoolMax is very similar to IRAC, but it keeps summers cooler and winters warmer in order to create the most temperate environment for your plants as possible. It’s a high-diffusion film that has all the properties of a 4-year IRAC, with a 75% light diffusion rate added. This added light diffusion will assist plants to grow while also avoiding overheating and evaporation of important moisture.
Our CoolMax products feature UV Open technology that transmits UV light directly to your plants, which benefits crops that need UV light for color (like roses) and flavonoids. CoolMax is a 4-year thermal film that is also anti-condensation. It contains IR, like IRAC, that helps trap radiant heat and raise the overall temperature of the greenhouse. It also diffuses the sunlight like a clear poly sheet, but it’s more effective with its IR thermal film.
Using plastic sheets to cover your greenhouse is a method that has worked for generations. It’s cost-effective, budget-friendly, and worth the investment. Plastic sheets can be just as durable and lasting as fiberglass coverings - all you need to do is make sure to cover your greenhouse frame thoroughly and secure them at strategic points to make sure your greenhouse is as sturdy as possible.
Though the concept of greenhouse plastic sheets may seem simple, those of us in the greenhouse sphere understand that that’s not the case. They involve some careful thought in order to make sure your plants are taken care of. With so many options to choose from that have a lengthy list of benefits for your plants, we understand how the decision process can get overwhelming. But we’re hoping - by using this guide - that it’s now a little easier to see what type of plastic is best for your unique greenhouse and growing capabilities.