Polyweave Greenhouse Cover –Photo Credit
Do a quick Google search and you will find pages on pages of sources explaining the benefits of growing cannabis in a greenhouse. Best of all, you get the controlled environment of indoor with the free light of outdoor. In a greenhouse, the main thing standing between the crop and the almighty sun is the greenhouse cover. This is why it’s important to choose a cover that’s best for your specific growing needs.
If cannabis is your forte, then I suggest you use a woven poly greenhouse cover because it promotes high light transmission and high light diffusion.
When you’re thinking of a cover think of light. Not all light is the same, and your plants do respond differently to the light they receive. There are UVA/UVB, blue, green, and red/far red/ infrared light spectrums that affect cannabis growth.For the most part there is no one light that is best for growing cannabis as they each produce different results at the different growth stages. However, you can increase your yields with more light even if it is the “wrong spectrum,” which is why high transmittance is important for your greenhouse cover.
Direct transmittance is the portion of light that passes through the cover. Having a high light transmission percentage signifies that the cover will let though a high amount of light. Diffuse transmittance is the portion of light that gets scattered by the cover. This is important because it allows for deeper light penetration ensuring that all the plants receive equally intense light. Below is an example of a cover that does not diffuse light (left), and a cover that does diffuse light (right). You can see that in the left image there are shadows and the right image there are no shadows.
“Although the intensity of light at any one point in time may be lower under a diffused film, the total light transmission is excellent, because the light bends around corners leaving no shadows. The plants may actually gain more PAR light (what the plant uses to grow) through the course of a day, with less stress.” – Atfilmsinc
If you live in an area with plenty of sun, you want a high light transmission and high light diffusion material. Your best bet is a Polyweave cover as it has an average light transmission of 85% with 100% light diffusion. The material is on the expensive side, but it is strong and could last up to 10 years in the right conditions. As long as you closely monitor your greenhouse’s temperature, then a woven poly cover could help you produce some of the best conditions for a cannabis crop.
Do you have any experience with this topic? What type of greenhouse cover do you use? Please share your thoughts in the comment section below.