Are Polycarbonate Greenhouses Better Than Glass?

Polycarbonate greenhouses have a huge number of benefits over traditional greenhouses. But at the same time they also have a number of weaknesses. So are polycarbonate greenhouses actually better than glass when all is told? That’s exactly what we’re about to find out…


Why Polycarbonate Greenhouses are Better Than Glass

Polycarbonate greenhouses have come on leaps and bounds in recent years. They’re now available in a huge range of different sizes and styles, and as a result have grown significantly in popularity. Here are the best things you should know about polycarbonate greenhouses in my experience… 

Cheaper to Buy 

Greenhouses can be an expensive purchase, make no mistake. Polycarbonate itself is far cheaper than glass, which means plastic greenhouses tend to be quite a bit cheaper to buy than glass. 

The lower price of polycarbonate greenhouses means you either get to spend less than you otherwise would have done, or you have the opportunity to upgrade to a larger greenhouse than you thought you could afford. Either way they represent fantastic value and a low-cost way to get into greenhouse gardening.

Easier to Construct

Polycarbonate is lightweight, rigid and doesn’t shatter or crack easily. This makes it incredibly easy to work with – perfect if you buy a greenhouse kit with plans to build it yourself at home. Compare this to how heavy glass can be, and how careful you need to be not to damage the panels and there’s an obvious advantage to plastic panels.

While all the panels of a polycarbonate greenhouse kit will normally come pre-cut, if you’re building your own greenhouse from scratch you may need to resize panels. Polycarbonate can easily be cut with a sharp craft knife so there’s no need to worry about glass cutters etc.

Safer to Work With

Plastic eliminates the risk of broken glass, which can occur not only when constructing your greenhouse, but even later if plant pots or footballs come into contact with a panel. 

While the edges of plastic greenhouse panels can be mildly sharp it’s really nothing in comparison to the dangers of broken glass. 

This can make polycarbonate greenhouses particularly appealing for those gardeners with children and/or pets. 

Repairs are Simpler

While most polycarbonate greenhouses are bought as kits – containing all the parts you’ll need – it is also simple to buy replacement panels in the future if they are necessary. 

These panels are cheap to buy, can often be shipped straight to your home, and if necessary can be cut to size easily. In terms of greenhouse construction, these panels typically slide smoothly in and out of your greenhouse frame, removing the need for fiddly greenhouse clips and so on. 

This means that making repairs to a polycarbonate greenhouse is typically quite simple – and cheap – as replacement panels are easy to source and fit. 

Better Insulation Levels

The twin-wall construction of most polycarbonate greenhouses means that they can warm up much more quickly than glass, and often retain warmth far longer in the evening. This makes for a warmer internal temperature.

While it becomes crucially important to properly ventilate your plastic greenhouse in summer to prevent it overheating, it also means that you’re often able to start growing plants earlier in the spring, and can continue long into the fall when most garden plants have fallen victim to cold weather. 

To give an example, my polycarbonate greenhouse has been known to reach 30’C / 85‘F even in February, when there is snow on the ground, with just a little winter sunshine driving that heat.

Why Glass Greenhouses are Better Than Polycarbonate

By now it may seem like I’m biased – that this is a propaganda piece convincing you why you should buy a polycarbonate greenhouse rather than a glass one. But hang on for just a moment. 

To give a fair and balanced argument it’s important we discuss the main benefits of glass greenhouses over plastic ones…

Sturdier Construction

Glass greenhouses tend to be more sturdily built, and as a result can stand up to bad weather rather better. 

Some glass greenhouse manufacturer’s make a point of designing incredibly tough kits, capable of people sitting on the roof without it cracking, for example. 

While my polycarbonate greenhouse has withstood winds of up to 60mph without too many issues, there’s no denying that watching those panels bending and flexing in the wind can cause quite a bit of anxiety. 

Glass greenhouses of course tend to withstand such an onslaught much better, though if any damage does occur then repairing or replacing parts can be more troublesome than with a plastic greenhouse. 

More Attractive Appearance

I’ll admit it – appearances count, especially in your garden. Glass greenhouses just look nicer. They come in a wider range of different sizes, styles and colors and mean that your glass greenhouse can really become a “feature” of your outdoor space.

Appearance-wise I’m a sucker for Victorian-style glasshouses, for example, while my current plastic greenhouse – while practical – is nowhere near as attractive to look at. If appearances really matter then glass is probably the way to go.

Easier to Clean

Polycarbonate greenhouse panels naturally flex and bend, meaning they can be a little frustrating to try and clean. Glass greenhouse panels are of course firm and sturdy, and can be easily wiped down at the end/start of the growing season. 

While cleaning a plastic greenhouse is hardly *challenging” if you want the least maintenance and the easiest time possible then you might want to choose glass over plastic. 

Potentially Longer Lifespan

This one is a difficult point, as it may not always be the case. Let me explain. 

Polycarbonate greenhouse panels have a finite lifespan. Over the years, with exposure to the sun and heat, they slowly become brittle and can start to allow less light through. The way they lose their flex and become more fragile means they can end up splitting in windy weather, demanding replacement.

In contrast, glass greenhouses are not structurally affected by exposure to sunshine, and in theory the glass panels could last for decades, even generations. The only issue is of course that they are easier to smash in the first place.

So whether glass greenhouses have a longer lifespan than a plastic one isn’t a given – it will depend at least in part on how well you care for the greenhouse and how lucky you are at avoiding any broken panes. 

Conclusion: What is the Best Greenhouse Material?

Everyone has their own opinion as to whether polycarbonate greenhouses are better than glass models. 

To a degree it’s a matter of personal preference – are you willing to put up with the extra expense and trouble of building a glass greenhouse, but end up with a beautiful building that should last for years into the future. 

Or are you happy to save money and effort in building a polycarbonate model, accepting that it’s unlikely to look quite as good as the more expensive glass versions, and that it may need to have panels replaced in the future (despite that being a reasonably easy task)?

Personally speaking I opted for a polycarbonate greenhouse in my garden. It’s a decision I haven’t regretted. 

It allowed us to buy a greenhouse much larger than we would otherwise have been able to afford – in our case a growing space 12’ long and 8’ wide. That’s a pretty generous space, especially here in the UK. 

With comfortable temperatures inside for much of the year, and (touch wood) no serious storm damage in the 2 years we’ve now owned it, my polycarbonate greenhouse has quite frankly transformed our gardening experience.