Updated: June 25, 2019
Owning a greenhouse is a constant battle to balance light and dark, hot and cold, wet and dry, but luckily you’ve got tons of tools in your arsenal. Besides all the climate control equipment, lighting tools and vent openers made to help you in your fight, there are several greenhouse cover options that block all or some of the excess UV light coming into the building.
Greenhouse covers are best when used to solve long-term problems, like extra-intense sunlight that comes in during certain times of the year, the loss of surrounding shade trees that have acted like UV filters in the past or a change in your greenhouse denizens. They can be difficult and time-consuming to install, so you don’t want to have to mess with them every day. Even though roll-up cover options are available for some types of greenhouses, they often require multiple people to open and close, and while easier than lock-in place covers, are still a pretty big task to manhandle.
Types of greenhouse covers
There are many types of covers that go beyond basic plastic sheeting, but they can be broken up into three main groups: shade cloth, reflective cloth and bubble insulation. Each can benefit the right greenhouse in a specific way. Let’s explore these options.
Shade cloth – This knitted polyethylene fabric comes in an array of weave densities, allowing manufacturers to control just how much incoming sun is blocked. Generally ranging from 30 to 90 percent blockage, the right shade cloth can help reduce the need to run fans and ventilate your structure, since it stops UV rays from directly entering the building. A good shade cloth will resist the elements, as well as mold and rot and they appear in different colors to better suit your landscape design.
Reflective cloth – Instead of blocking sunlight, reflective cloth bounces errant rays away from the greenhouse, preventing them from heating up the surface of the greenhouse as well as the inside. Reflective cloth can block 30 to 80 percent of incoming sunlight, but also helps greenhouse growers save up to 25 percent off their energy bills by acting as an insulator, as well. Although this dual-sided material can be quite pricey when compared to plain shade cloth, it can do double-duty and be applied to the inside of the greenhouse to help protect it from damage.
Bubble insulation – If the sun is a much-wanted guest in your greenhouse and you need a little help keeping in the heat it brings to the inside of the building part of the year, bubble insulation is for you. It’s made using the same process as bubble wrap, but bubble insulation is generally much stiffer and more resilient, making application to the inside of your greenhouse simpler. The air pockets act as a barrier to prevent the heat inside your structure from moving outside, raising the indoor thermometer by several degrees, even in the coldest winter.
Depending on the time of year you need to take cover and what you’re hoping to accomplish with your efforts, shade cloth, reflective cloth or bubble insulation are easy, inexpensive solutions for your everyday greenhouse temperature problems. When used in conjunction with your other greenhouse equipment, you may find you’re saving more money and growing better plants by simply applying a cover part of the year.