Use Greenhouse Polycarbonate Sheets to Extend the Growing Season

There’s a host of vegetables that you can still grow at this time of year, and over winter, including broccoli, brussels sprouts, cabbage, kale, leeks and parsnips. All of these would benefit from some protection from the wind and cold especially as seedlings, and the following, cut and come again leaves, would be best grown under shelter from beginning to end; Chard, parsley and rocket.

Traditionally glass has been the gardener’s choice for greenhouses and cold frames however, the fragility of glass can often mean that it’s also the more expensive option. With it being all too easy for glass to crack under the weight of a falling apple, toppling trough or low flying bird, the strength of a polycarbonate sheet is becoming more and more appreciated in the gardening world.

Polycarbonate sheets are so strong that I have seen a salesperson offering freebies to any passer-by that can smash his polycarbonate board with a hammer. None succeeded and the prize went unclaimed. So, it’s easy to see how the lifespan of a polycarbonate sheet for a greenhouse panel often far outweighs that of glass, and, because it’s virtually unbreakable it also makes a great choice if you’re having a helping hand from any little ones in the garden.

Polycarbonate is brilliant at offering protection from hungry pigeons and other pecking pests that are keen to nibble on your plants as well. But how warm can it keep your seedlings? Well polycarbonate boards offer brilliant insulation, even more so than some horticultural glass which tends to be 3mm thick with an r value of 0.93. Special Greenhouse Polycarbonate Sheets are 4mm thick and have an r value of 1.42.

Greenhouse polycarbonate has brilliant light transmission, but you would be forgiven for thinking it’s not as good as glass, in fact, it’s simply different. Glass has a light transmittance of 97-98% and 4mm polycarbonate only has a light transmittance of 80-84%, however, when light goes through the twin wall of the polycarbonate it scatters, becoming diffused. This has an amazing effect as the light reaches every nook and cranny, more so than when it is going through glass. And, because the light is spread around when it goes through polycarbonate your plants will get an even amount and grow at the same rate. And if the panels become muddy, simply wipe them down with a damp cloth.

The clear polycarbonate is also extremely light in weight so it’s a fabulous material if you’re working on it by yourself as it’s very easy to lift and move around. They’re easy to cut to size yourself, you can simply use a pen or utility knife to score the material and then snap it along the score (make sure you wear some protective goggles!), you can also use a circular saw or Jigsaw if you prefer. Wikihow has a great guide on cutting your 4mm polycarbonate, which is well worth a read.

To give growing seedlings or established plants protection from severe winds and heavy rain you have a choice of what to make to protect your plants with, a cold frame, greenhouse or cloche.

A cold frame is brilliant if you don’t have enough space for a greenhouse or you want something a little simpler to build. Here’s a guide that you can follow with a step by step of how to make one. In this guide it’s recommended to use Vistalux PVC Corrugated Sheeting however for the winter months we recommend using Greenhouse Polycarbonate instead to keep the plants warmer and ensure there are no gaps. To make an even easier cold frame try to find some form of enclosure or weather resistant box that you can fill with soil or pots and cover with polycarbonate sheeting, an old sandpit for instance, is perfect.

But ultimately, a polycarbonate greenhouse will give you the most room if you are hoping to grow a large selection of plants. To use polycarbonate, you will need to build a frame first, this gives you the freedom to build the perfect greenhouse for you and your garden or allotment. You can find lots of different designs for greenhouse frames online and Roofing Megastore sells 4mm Greenhouse Polycarbonate Sheets in two different sizes that is perfect for the walls.

The final option is a cloche which is the simplest option but will not keep your plants as warm as something that is completely enclosed such as the cold frame or greenhouse. To make a cloche we recommend using Vistalux PVC Clear Corrugated Roof Sheet rather than the Greenhouse polycarbonate as it will bend easier. Here’s an article which will guide you through creating a cloche quickly and easily.

Once you’ve created and established your greenhouse, cloche or cold frame then all you need to do is choose what you want to grow! And, if you need any advice on how many sheets you need for your project, or anything else, feel free to give our friendly team a call on 01295 565565 or speak to us via the handy live chat below.