1. Material Used for the Greenhouse Plastic Sheeting
First, let’s take a look at the material of greenhouse plastics. There are generally three types namely Polyethylene, Copolymer and Polyvinyl. These materials work pretty much the same way; they only differ in life span.
There is another type of greenhouse plastic known as Polycarbonate. However this type is essentially two layers of polyethylene. This is the strongest material used for greenhouses. In fact, it can last up to 10 years if properly cared for.
2. Thickness and Number of Greenhouse Plastic Sheeting Layers
Second, let’s talk about the layers of the plastic sheeting. Like I said, some greenhouse plastics come in single and double layers. The number of layers in a sheet will determine its durability and functions.
a. Single Layer
This type of sheeting is cheaper compared to double layer sheets. It’s also easier to install and maintain. However, it’s less durable compared to double layer plastics. In addition, it doesn’t fair well during the heating season.
b. Double Layer
This sheeting is stronger than single layer sheets. In addition, it doesn’t put too much stress on the frame and other points of attachment. However, double layer sheets are prone to condensation in between the layers, thus additional maintenance may be required. Plus, it’s a lot more expensive.
Aside from the number of layers, another factor that determines the durability of plastic sheeting is thickness. Its thickness is measured by “mils” wherein 1mil=0.001in. The general rule is; anything below 6mil is adequate for normal operations for a year. However, those who need better protection should to purchase sheets that are 6mil or thicker.
3. Ability to Control Temperatures
All plastic sheets have the ability to control the temperature within a greenhouse. However, let’s take a closer look at the material’s heating and cooling capacities.
It’s normal for a greenhouse’s temperature to go down at night. However, this can be a problem during fall or winter when the nights are too cold for most plants to stand. That’s why it’s important to get sheeting that’s treated to help retain heat.
Properly treated sheeting can reduce heat loss by up to 20%. A double layer sheeting helps reduce heat loss by 40%. And if in between it has an infrared (IR) layer, its heat retaining properties are improved.
Some plants prefer to live in warm climates. However, plants will dry and shrivel up if the heat in the greenhouse is too high. Greenhouse sheeting can help by preventing some of the sun’s infrared rays from entering the greenhouse.
4. Ability to Control Light
Plastic sheeting also differ in the way they control light. Clear plastics will allow a lot of light to pass through, but it makes the greenhouse prone to shadows. This means there are places where plants do not receive adequate light. Opaque plastics help disperse light evenly, but it doesn’t allow enough light for germinating seeds to grow.
The things I mentioned above are only simple concepts regarding greenhouse plastics, so you may need to do a little more research before buying. Greenhouse plastic sheeting may look simple enough, but there’s actually a lot more to it than most people think.