Which greenhouse?

Can anyone tell me how the new polycarbonate greenhouses compare to normal glass ones, and which type would you recommend?

Personally, I prefer a glass greenhouse. But which is best for you depends on your circumstances.

One big difference is the price; glass greenhouses are more expensive.

A glass greenhouse will probably be more difficult to erect. Glass is much heavier and needs very careful handling. But a glass greenhouse will also tend to be more substantial and longer-lived.

Polycarbonate greenhouses are a lot lighter, in terms of weight, so they need securing to prevent them from being blown over by high wind. Glass greenhouses are so heavy that they normally hold themselves down, or need minimal securing.

I don't know how well modern polycarbonate ages. At one time, polycarbonate gradually deteriorated with the effects of sunlight, and became opaque, but that may be improved now.

Glass is also more susceptible to breakage, and is potentially more dangerous, so that might be something to consider if boisterous children or pets are around.

There is hardly any difference.

Polycarbonate lets in very slightly less light, but it's only about 2% less. Dirty panes shut out far more light than that.

The most interesting difference concerns insulation. This is only important if you want to keep tender plants through the Winter. In that case you need to provide heating. What is at stake is how much heat the greenhouse loses (and hence your electricity bill).

As you'll know, with a normal house you can limit heat loss through the windows by using double glazing. A greenhouse is all windows and loses a lot of heat. I don't know of any glass greenhouses that are double glazed (they would be very expensive).

A standard polycarbonate greenhouse has about the same insulation as glass. However, there are a number of polcarbonate greenhouses on sale which do have twin-wall insulating polycarbonate. These are very popular on the continent, where cold Winters are common.

Again, thank you very much for your advice.  I will have to have a good look round before I invest.  I hadn't thought of putting tender plants in there over winter (I have a nice sunny windowsill that does that job!!).  It would be more for salad crops, and sitting in with a good cup of tea and reading the latest edition of Gardeners' World, enjoying the sunshine. 

I would always and have always had secondhand greenhouses. Some excellent ones are often either given away or sold cheaply in the local newspaper and elsewhere. Spend the money saved on staging/plants/automatic window opener.

glass every time.

i thought about a poly one , but ended up buying an aluminium one out of the local paper . it was 5 years old ,but never been out the box . cost £ 40 then the price of the glass £100.......good luck in your search....

The best advantage of polycarbonate for me is the insulation. It can keep the temperature of the building constant. Polycarbonate greenhouses are being popular because of the huge difference in the cost in comparison with the glass greenhouse. Glass greenhouse is a good preference if you are not living with children because it can be prone to breakage and cracking. Polycarbonate is lightweight and ensures ease of construction and transportation. 

What a useful discussion! We got rid of our glass greenhouse last year, to reclaim a bit of garden. I didn't overwinter plants in there because of the cost of heating. A small double-walled polycarbonate greenhouse sounds ideal for me and would be easily moved if necessary. Thanks for raising this topic, Andrea6.

Have found whilst researching that polycarbonate greenhouses deteriate with age, so could potentially be more expensive in the long run, as will poly tunnels. That said, if you're not planning to live at your premise for a long period, then it might be worth getting a cheaper poly tunnel or polycarbonate greenhouse as you can simply dispose of it and buy another one at a later date.

With regards to glass breaking easily, I understand that that's a genuine concern where money is not available, so standard horticultural glass is provided, but I've got mine from greenhouse direct (Rhino harvester) and it has come with 4mm, single pane, strengthened safety glass. The idea being, that if it were to break, which would take some doing even at 3mm thick, it will shatter like modern car and bus windows, into tiny granular like pieces. This does cost, but that said, I'm in for the long haul and think that with 25 years of guarantee as standard, it's worth it. Again though, if I were going to move in 3 - 5 years time, I'd go polycarb everytime as it's just not worth the hassle of having to dismantle and re-build. There is one obvious downside to this thinking, and that's environmentally, it's very much a disposable method and I can see why many would think this senseless.

Polycarbonate is the best choice now. It's cost effective and very much durable and a good insulator of heat.

pauline j.

Looking back, though glass is better as a long term option, I'd have to agree with Pauline, that based on your use of a greenhouse, a polycarb one will be a much better deal. Polycarb is definitely a better option on the cheaper range as you don't have to worry about the dangers of standard horticultural glass. That said, if you feel you might regret not going bigger and more expensive incase the greenhouse bug bites, then I'd go with a 3mm thick saftey glass greenhouse everytime.