An update on the bubble-wrapped greenhouse: was it worth it?

As you guys know, we wrapped our greenhouse up in bubblewrap this year to keep it as cosy as possible without installing heating. We had 100% expected that by now we’d be able to give you a proper update on how it was standing up to the frosts and cold of winter… but to be honest, mother nature has other plans. It’s still not actually cold.

See our original post about actually wrapping the greenhouse

So instead, let’s have a chat about our thoughts and experiences so far and… when it does get proper cold, we can update you all further on the adventure.

So what I did was, I put out a call on social media asking you all to give us your questions, what do you want to know about the experience. If you don’t follow us on social media, pop up to the top right of this blog post and you’ll see the links to our various channels there.

What was really interesting about this, was I was pretty sure I knew what kinds of things you guys would want to know about, but boy was I wrong. So I’m glad I asked.

Let’s go for the biggie and most obvious one first.

Does it work?

Well, I suppose that is all dependent on what you consider to be the purpose. For us, our purpose for wrapping the greenhouse was to try to add some more protection against the frost, especially for our hydrangea. We chatted about this a few weeks ago when I told you guys that I bring them into the greenhouse over winter. However, once we had the greenhouse wrapped up, that original idea expanded and I decided to try my hand at keeping some things alive over winter as well as a blooming mental idea of growing carrots in there in pots. So now, when I say did it work? I have to consider all of this. Shucks, talk about making work for myself.

OK so let’s address the first thing then, we haven’t actually had any frost yet, so I can’t yet tell you if the bubble-wrap makes any difference in regards to that. What I can tell you though is that in order to protect the plants from the frosts, it means the greenhouse needs to be warmer than the frost level temperatures. That kinda goes without saying for the growing things in there over winter, the temperature in the greenhouse needs to be within the range a plant needs to keep active.

So what has the temperature been like then, well I’ll go into much more detail in a sec, but generally, yes. The greenhouse has felt warmer than the garden does generally. It was especially noticable right at the beginning of Autumn when we got the bubblewrap up. There were still a few days when we had some proper sun, even if we didn’t get the summer heat to go with it. We noticed then, that even though the general outdoor temperature in the garden was around 16, because it was sunny, the greenhouse was actually baking at 30C. That was a big shock for us, we would only expect maybe 20C. It didn’t last though, we are talking one or two days. But still it was really interesting to see that the bubblewrap really does a great job at keeping heat in, if the greenhouse gets warm.

So let’s get a bit more specific then. I did cover the specific outdoors versus greenhouse temperatures (with a graph and everything) in the relevant video over on youtube, so have a wee watch of that video if you want to get properly in-depth about things. But generally, a marked difference.

Currently, the garden temperature is

However the greenhouse is

Now I know a few of you will think, that’s only 3 degrees difference. Surely just the fact that it is a greenhouse should make that difference. Which is fair enough. However, this is one the things about greenhouses that gets misunderstood. They aren’t just warm by their very existence. They do need a source of a warmth. They work by reducing the heat loss. So on a sunny day, greenhouses get very warm because they hold that heat from the sun. However, it will dissipate so once the sun goes in the evening, the greenhouse is cooler again. Just now, we are seeing very, very little actual sunlight, we are pretty much under a blanket of cloud all the time. So although that cloud means we are not freezing cold, it also means there isn’t a lot going on to heat the greenhouse up, so on these days, I really wouldn’t expect to see the greenhouse be more than a degree warmer, to be honest.

What this is telling me though, is that the bubblewrap is doing a really great job at slowing down that heat loss. So at the minute, hurrah! I’m not so sure how much impact that is going to have once it’s proper cold though, once we get very little, if any heat from sunlight and when there is much less light at all during the day. We shall have to see.

Does the bubblewrap block out the light?

This one was a brilliant question, and it was one of the things I had started to think about. The simple answer is no. It doesn’t block the light, it is actually still really bright in there. However, that’s a bit simplistic.

So it doesn’t make it dark in there, is probably a much better way of saying things. But the bubblewrap does act as a massive diffuser so the light is much more subtle. It means there is no direct sunlight. Now for a lot of plants, this is a good thing. A lot of plants don’t like direct sunlight. What I just don’t know at the minute is if that diffused light will somehow be a negative. I don’t know if it will stop the carrot seeds from germinating or indeed if it will affect the growth of the plants in there. I’m afraid it’s one we are just going to have to watch and discuss at a later date when we have more data. What I need is a light meter to measure the light……. hmmmmmm

Do you get condensation?

OK so this one is actually something I wanted to talk about and I was actually really surprised when it wasn’t mentioned at all. I thought this would be a genuine concern for more than just me. Again though, it’s not the simplest to answer.

I have always had an issue with condensation in the greenhouse. You’ve seen me post pictures of it. Generally, if it’s been warm in there and then the temperature drops overnight. We wake up in the morning to see the greenhouse fogged up and have to go open the windows to air it out.

So here’s the thing, at the time of recording the video to chat about the bubblewrap, I hadn’t seen any condensation in the greenhouse at all. I was really surprised. Since then ( a week or so ago) I have noticed that I am starting to see condensation on the roof. This might not seem like a big deal, but when you consider that the bubblewrap is covering all the windows and vents, meaning we can’t air the greenhouse out the way we would normally… there could be a risk of mould and mildew caused by this condensation, so I will be keeping an eye on this. An eagle eye.

The other thing I have noticed is that if an area in the greenhouse gets wet, it then doesn’t dry out. For instance, around the base of the greenhouse I’ve noticed it’s quite damp from where rain etc comes in under the base. This is just sitting and doesn’t seem to be drying out. So again I’ll keep and eye and keep you guys up to date, because I am a wee bit jittery about it.

However, to answer the question, was it worth it… well, so far so good, but we’ll need to keep checking back as the weather changes to see how it fairs long term over winter.