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 up front. 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.

Greenhouse wind damage

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.

Just for a bit of daft fun, here is the other use we made of the greenhouse at christmas…

A greenhouse update: spring 2019

There was much excitement when we replaced that rickety old polycarbonate greenhouse with our shiny new glass one, but it was excitement about having a new toy rather than of what was to come, because at that point, we really didn’t know what to expect.

So since it’s spring and we are actually using the greenhouse now, I thought it might be time for a wee update on how we are getting on and what we think of our new toy.

First thoughts


Well the first thing I notice is that the glass greenhouse seems to take the heat a lot quicker. We are seeing the automatic windows opening way earlier in the season that we did previously and the greenhouse generally does feel warmer. Probably because it doesn’t have a howling gale going through it and rain seeping in. Yep you read that correctly. The old greenhouse was never quite water or wind tight. This one however, feels solid!

It’s not yet at the point in the year where the temperature is unpleasant in there, but there is a marked difference between outdoors and inside the greenhouse. Can’t wait to see how this changes as the weather changes.


Also it seems to stay clean which is a crazy thing to say because obviously I didn’t get a free shift of elves with the greenhouse sale who come in during the night and clean up. Or did I?

Check out youtube to see the naughty elf in the greenhouse.

But it does, it seems to stay clean. The glass is still clean. The old polycarbonate greenhouse got taken apart and cleaned every year because green sludge built up everywhere, also the polycarbonate discoloured badly.


I also feel like I’ve got way more space, even though it’s exactly the same size. I don’t know if this is because I have more headroom in this one, but it definitely feels bigger.

There is also one thing which makes a huge difference but it’s not exactly the greenhouse. The new staging. I used to use cheap and nasty wire shelves which to be honest weren’t really much use for anything other than storing things but the new staging is really solid and practical so I can actually use it for potting on etc. It just makes the whole space feel more useable.

I am really happy pootling away in there and I feel like I can pootle and do so much.


One of the things that’s new and a bit exciting is that I can now hang baskets inside the greenhouse. Before I had to do a kind of magic balancing thing with an upside down stool but the new greenhouse, apart from being really solid, has rails for hanging stuff. Means I can have the baskets in there while the plants mature a bit and grow.

Only downside though, I keep forgetting! They are hanging just a t my head height.

Some more maker fun, we tried our hand at glass blowing.

You guys know how much Kate and I enjoy being creative and making things but this month we got the opportunity to take things up a notch or two and have a go at the type of making that we just couldn’t have tried out for ourselves at the dining room table. This month we got up close and personal with molten glass.

Kate shaping a creation under the careful eye of Ingrid, our teacher.

We are really lucky to have access to the most amazing community of artists and makers in Edinburgh and East Lothian, and Ingrid (who teaches glass making at Edinburgh College of Art), runs workshops for beginners on various weekends over the year.

As you can imagine, the glass workshop is hot, hot, hot and scary at first, but with a good teacher to take us through techniques and safety rules it becomes less scary. There are a lot of safety things to think about! We were both appropriately nervous when we arrived but by the end of the day, those nerves had given way to excitement at what we’d done and what we could do next (oh yes we are all set for a more advanced workshop in the future).

So what did we learn to do?

Well, apart from learning about all the tools and what they are for, jacks, tweezers, blow-tubes, punty irons, blocks and paddles etc. We also learn some of the basic techniques needed to make some beginner goodies. We started by learning to use the jacks to shape and cut in by making little “marbles”. It was all about learning to keep the glass turning, as gravity will pull the molten glass, while shaping and directing things.

Eli learning to cut in using the jacks

Once Ingrid was happy we’d got the hang of controlling and shaping the ball of fire on the end of that big metal pipe, we moved on to the excitement of actually blowing the glass. Kate even had a go at seeing just how big you could make a glass bubble get before it went pop.

So of course, we had a bubble but once you can make a bubble, then you need to learn to shape it it into what ever creation you are making.

They all require shaping in different ways and Ingrid taught us all the techniques to do each of these.

You may for instance, use the paddle to shape the base so that it’s flat.

Kate flattening the bubble to make her vase

Or you may use the edge of the jacks to open it out and and flatten the outside.

Eli opened up her bubble and flattened out the sides with the jacks to make a bowl.

We also had a go at a technique called “necking off” to elongate and stretch the molten glass. In this case literally to make a neck, for Kate’s vase.

Kate creating a neck on her vase

Eli got all fancy giving a glass a fancy tulip shape by using the jacks to flare things slightly.

Eli adding a small lip to her glass to make it unique.

You’ll notice as well, there is a gorgeous purple spiral on Kate’s vase, above. We did a lot of working with coloured glass in the afternoon which was fantastic. Learning how to add colour in different ways and how to manipulate it was so interesting. For me, learning how to create little bubbles inside my blown piece was so cool. I’d always wondered how that was done.

Oh, and let’s not forget that you can also have the help of your friend gravity to shape things. Although to be honest, I was just playing at being a wizard!

We have to say thanks so much to Ingrid and Meg (who took the photos) for a very fun and amazingly interesting day where we learned so much. We’ll be 100% doing more of these classes.

So, I bet you are dying to see our finished treasures?

We both made christmas baubles, paperweights and glasses (I forgot to take a photo of them sorry) and Kate made a vase and I made a bowl. Kate went for purple and pinks and I went for blues.

If you want to see how it’s done properly, check out Ingrid & Meg’s websites.