Greenhouses: glass versus polycarbonate. Is there much difference?

I wrote a blog post a good while back now asking if an unheated greenhouse really made much difference and I think having one here in the cold, wet north really was a great tester.

In that post, one of the things I commented on was the fact that I had no experience of the difference between a traditional glass greenhouse and a polycarbonate one, so couldn’t offer a more specific analysis.

Well we are at the end of our first spring season with the new glass greenhouse now, so I thought this would be a perfect time to give you an update and tell you if there is a difference or if you should save your pennies and stick to the cheaper options.

So let me answer the question straight off, which is better glass or polycarbonate?

Glass, absolutely no doubt. I don’t think I could switch back now.

There you go, blog’s over :P. Kidding…… let me tell you about my experience.

If you are a regular here you’ll already know the stories of my greenhouse and its travels, but bare with me as I let the newbies in on our adventures.

I have had a polycarbonate greenhouse for about 6 or 7 years now. It was a few hundred quid, so was affordable whereas at the time of buying it, I couldn’t really afford to shell out a grand on a glass greenhouse when this was my very first trek into gardening and I didn’t even know yet that I was going to be hooked.

And let me say this upfront. I was VERY happy with my greenhouse. It really made a difference and I found seeds took faster and seedlings came on faster than anything I planted outdoors. It also offered protection from frosts and in summer when it was sunny, it doubled as a staycation resort.

However, the thing it didn’t cope with was wind and rain. Basically, if it rained, the greenhouse leaked like mad. Water got into the corrugated roof panels and they filled with green, algae-type stuff which meant cleaning every year was a massive job and less than pleasant.

When it was windy, my heart was in my mouth, regularly I would have to go on early morning treks around the neighbourhood looking for roof panels which had blown off in the wind and gone off on their own adventures and the greenhouse ended being held together with gaffer tape and hope.

Things finally came to a head last year when I lost multiple panels, most of the clips that held the roof in place and the window was torn out by the wind and completely bent and also ripped the frame so it couldn’t be fitted back in again. We decided enough was enough and bought a glass greenhouse which advertises specifically that it is capable of coping with even the worst winds.

We got it installed in November though, so spent the winter with a beautiful shiny new greenhouse but nothing to grow in it.

Until now… I can finally give you an update on my experiences and compare.

Glass versus polycarbonate

So as I said, the polycarbonate greenhouse absolutely did its job when it came to growing stuff. Seeds germinated and seedlings grew and things definitely came on faster than outdoors.

However, this spring with the glass greenhouse, EVERYTHING grew. EVERY SINGLE SEED. Leaving me with a massive conundrum, because I always plant more than I need, because usually only about half came up. Basically, I gave away 20 tomato plants and a similar amount of peppers and chillies this year, as we had so many healthy, strong plants. Not only that, but once things had started, they came on at an alarming rate (well alarming for me).

The other big difference I notice is that the glass greenhouse is so well put together, there are no gaps for wind to whistle through and no leaky spots. The whole thing just feels solid.

Also noticeable, which was a bit weird for me at first, was the temperature change. In February when normally everything is freezing, there were days when the greenhouse was sitting at 19 degrees C. Really!!!

So I guess from here on it’s a case of watching and comparing to previous years, but so far I can definitely say that yes there is a big difference between glass and polycarbonate, but, glass is expensive so if it’s not an option for you, polycarbonate just might be.