[Casey76]

For some reason the price of greenhouses "over here" are absolutely scandalous.  It's as if they are a recent invention and are still new and not to be trusted!

My supermarket has one advertised, and it is the cheapest on I've seen.  It is 6'x6' (I think, looks like 2x2m) and is 249€  For that price I could get one almost 3x as big delivered from the UK!

Anyway, are PC greenhouses any good, and what kind of base would they need?  If I drilled through some paving slabs to screw it down, would that be OK?  I'm thinking about something like this: http://www.ebay.co.uk/itm/Greenhouse-Polycarbonate-Aluminium-Cold-Frames-Grow-Plants-Growhouse-Garden-Alu-/141265522588?var=&hash=item20e414cf9c:m:ml-yzSMsFaG7_mEcpUdOj6g#shpCntId

Thanks!

[BabbyAnn]

polycarbonate greenhouses are fairly lightweight (last year I was able to (slowly and carefully!) drag my 8' x 6' about 10 feet down the garden to make way for another project) and the polycarbonate sheets come in various thickness - the thinner, the more flexible and therefore easier to pop out in strong gusty wind unless you can position it somewhere sheltered.  But as greenhouses go, mine is fine (no better or worse than a polytunnel or glass greenhouse)  Polycarbonate eventually weathers and is easily scratched so you have to be careful when cleaning.

As for the base, make sure it comes with a base (some designs include it in the greenhouse frame, some you have to purchase separate)  Make sure the ground is level as that can make a difference when putting the panels in (if the frame is slightly skewey, then the panel won't fit nicely)  You can screw the greenhouse down to a paving base if you want, but mine is anchored down with lots (and lots) of tent pegs into the ground.

Like all flat pack greenhouses, you need a degree to work out the instructions, and some.  I've managed to build 2 on my own, but a third one defeated me and I got a polytunnel instead. 

[surbie100]

I have a palram greenhouse (think slightly more rigid than clingfilm) and it's brilliant, if fairly damp inside compared to glass ones on site.

I have it bolted onto 4 sleepers. It raises the structure, plus the sleepers made it really easy to level the ground properly. It's survived the storms with only one panel popping out, and at least that didn't involve glass shards everywhere.

[mumofstig]

I used silicone to fix the panes in on my Norfolk greenhouse, and they've not popped out since, despite a couple of storms that flattened the fence 
The 'panes' are beginning to discolour after 8 years, so will have to start looking around for replacements that will hopefully, work out cheaper than the Norfolk ones.

[Plotmaster]

Like Surbie, I also have a second hand Palram and I have just bought a new one for my second allotment and I think they are fantastic. I'm a little worried about the second one as it is a much more windy site and a metal shed was taken for a ride up the allotment. I shall be putting green debris netting over the whole greenhouse as shading anyway so hopefully if a panel gets loose the netting will keep it some where near the frame.

[Trikidiki]

I'm a nay. I prefer glass. I think poly-carbonate may be slightly warmer but you don't get the damp problems as bad in glass.

We foster kids and I am having a constant battle with social workers who want me to replace the glass in my two greenhouses with poly-carb or toughened glass, despite the fact that the kids aren't allowed in the part of the garden with the greenhouses unless supervised.

[LandShark]

Yay ! For Polycarbonate.
We inherited an old 8x6 when we moved. I ended up removing all the glass after a pane fell out the door when I was closing it. Luckily I only had a small cut on my hairline but it gave me a fright!
So I took out all the glass and bought a cheap polycarbonate glazing kit off an auction site. Siliconed it to the frame and used the spring glazing clips for added security. After 2 winters they're still in place.

[chickpeacurry]

Hi the program greenhouses which are being mentioned is there are shops were you can look at them. I can only see them on line.   I am hesitant re polycarbonate due too others having them blown away. There is a problem with glass getting vandalised so not sure what the best option is. I would go for polycarbonate if it was really clear and thick and the pains were secured. The polycarbonate at b and q look incredibly flimsy . What is the difference with the greenhouse s from the recommend company.  I would prefer polycarbonate if I could get a really good quality plastic. I would also like to see before hand and if they only sell on line you cannot do this. Thanks

[wapello]

 Single wall polycarbonate is what i use  for closhe's  easy to cut dont rot easy to bleach clean just the  job,,
 but not for a green house,i like to look out,,,

[grendel]

I have a 6'x4' one in the back garden, just tucked in a corner, wouldnt have one at the plot, but this has withstood some winds that took our folded up parasol for a short trip.

[sunshineband]

Lots of plotholders here have similar polycarb greenhouses an they have stood up reasonably well to the gales. A bit of shelter on the windward side helps a lot, and I agree with MoS that gluing in the panels with silicone stops them popping out.

They do need securing to the ground in some way and the most stable ones are attached to a line of bricks or some slabs by bolts.

They are excellent value imho, when you compare them to the cost of glass, especially toughened glass. My glass greenhouse gets plenty of condensation inside it, which is easily dealt with by opening a vent or two.

[lazza]

I realise I'm a bit late to this debate, but thought I would add a dissenting voice!

I have a polycarbonate lean-to down the side of my house. I have very little space to grow at home, and no allotment at the moment, so I squeeze in as much as I can in the spaces available. The lean-to (6' x 2') is in a 4'-wide passageway down the side of the house between the south-west facing wall of the house and the external fence.

I've had it 4 years, and it's been rubbish!

OK, I should qualify that: I have actually got decent crops of tomatoes from it, and successfully grown chillis and cucumbers in it, too. But because of its placing down a passageway, which funnels the wind, the somewhat flexible polycarb sheets very soon got blown out of their metal frames. It's almost impossible to get them back in once they're out because the edges get "frayed" and then won't fit in the frame-lining. Most of the sheets are now fixed in with water-proof masking tape, a process I have to go through each Spring, as they all fall out again over the winter! And most of the sheets are also now very brittle and stained yellow, especially those at the top, which get the most sun, and some have pretty big holes in where the plastic has cracked and broken.

I think it's probably on its final year now, so I'll need to replace it for next year, I think, so all-in-all, it will only have last me 5 growing seasons.