Greenhouse Growing: plastic or glass?

What to Plant in May Greenhouse Dunster House

If you type Greenhouse into Google, you will be inundated with hundreds of different ranges, styles, sizes and materials. It can quickly become overwhelming especially if this is your first venture into gardening. I was looking through the different images and found Greenhouses with plastic panes instead of glass. So, what is the difference between them? They are both clear, tough (in our case) and strong materials that let the sun stream through – right?


At first, both the glass and the plastic will be transparent and let natural light stream through the panes. However in a report entitled Greenhouse Lighting written by A.J. Both, an Assistant Extension Specialist at Rutgers University, he explains that when rigid plastics are used such as polycarbonate or acrylic its light transmission (transparency) “decreases overtime as the plastics age and turn yellow due to the amount of UV radiation contained in sunlight”[1]. When you compare this to glass which provides much higher light clarity and generally lasts longer, you can see a clear (pun intended) winner.


Plastic and Polycarbonate is cheaper than glass with some of them starting from as little as £200. However, plastic ages after a few years and needs to be changed which means you will be consistently paying for it for years to come.  With a glass Greenhouse, especially toughened glass like ours, you will pay a little more initially but it needs a lot less maintenance than plastic. Our 4mm toughened glass is significantly stronger than the standard 3mm that is found on the market today. In gardening terms it means that the window is less likely to break if an over excited child miss aims their football or a fast flying bird hits the glass (it’s been known to happen). Another benefit of toughened glass, which in my opinion makes it worth every penny, is that it crumbles rather than leaving shards of glass hanging dangerously.


Of course the most important factor when buying a Greenhouse is the insulation it offers for your plants.  Polycarbonate Greenhouses does naturally have increased insulation, however, by using full panes of glass with no overlaps, we create a warmer greenhouse whilst our internal beading reduces the chance of droughts. Keep in consideration that more sun can enter the greenhouse through the clear glass making a warmer temperature within the greenhouse making it more efficient than plastic. An article by the Royal Horticultural Society stated that polycarbonate sheeting transmits just 83% of light – considerably less than glass – with acrylic plastic only beating it slightly at 85%. Glass lets 90% of light through and, unlike plastic, reflects heat radiated from within the greenhouse back into the structure so it is not lost[2].


The last thing you want when you own a Greenhouse is the possibility of it blowing around or becoming twisted in the high winds that the UK is exposed to on a regular basis. As we use toughened glass, and full panes, it is nice and heavy as it is thicker than both plastic and 3mm horticultural glass (glass is still heavier than plastic and, if not purchasing our toughened glass, always opt for glass). The extra weight it generates helps ground your Greenhouse and gives it much greater resistance to high winds. In addition to that, we offer heavy duty framework to help support the glass further.

As with everything, you get what you pay for. If you are interested in creating an environment where plants have the possibility of growing all year round then you need to take a look at our range of Greenhouses. We have a variety of shapes and sizes perfect for all levels of gardener. Visit to see our full range or call 01234 272 445 to discuss this further with our knowledgeable team.





May 21, 2015

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