Topic: glass greenhouse vs polycarb greenhouse

[darren2007]

hi all I've currently got a poly carb greenhouse 6x8 last year and  didn't have much luck growing seeds as it got to hot but this year I've fitted an auto vent opener and also put shading down one half so now I'm ready to grow but i don't know what I'm do-in wrong my seeds are all germinating but not grow very big i currently have pak choi ,toms,cali,broc but noting seem to be growing past the first leaves stage ( no true leaves growing ) some are showing signs ov true leaves and some look like their dying, but now I've just come in after been to look in my brother in laws glass greenhouse and the difference in there is unreal was looking at his pak choi and it looks like it ready to use as baby leave we planted nearly around the same time and my still at the first stages all his other plants are prob over 4 times bigger than mine  I NEED HELP WHAT CAN I DO
forgot to say my seeds are also in a 4 tier plastic mini greenhouse which i zip up a night so they don't get to cold and but heater on if drops below 10c

[Bugloss2009]

too hot in the day?
irregular watering?

pac choi, broc, cauli don't mind it being cool. personally i'd not use the heater at all, and move the toms into the house for a few weeks

maybe your 4 tier greenhouse is too small for a heater - it produces too much heat.
 Also 10 ^oC is quite a high temp to start worrying about. More like 4-5 ^oC, even that wouldn't worry me, so long as I had nothing tender

[darren2007]

think i might ov put it wrong my 4 teir greenhouse is covered up and sat in my 8x6 poly greenhouse which has the heater in

[steve76]

I have a 6 x 4 polly carb greenhouse, had it for about 3 years now with no probs, i have a heater in it but its set on frost stat only.
The only problem i could say with it is the sheets are starting to crack and will need replacing for next year which is going to cost nearly as much as the whole greenhouse cost me :(

[chriscross1966]

try Greenhouse Warehouse.... I've found them very reasonable for the twinwall I've just been buying fro my GH..

chrisc

[Jeannine]

Having had glass houses all my gardeninbg life until now. I have a large poly one. The panes are plastic double walled sheets os something rigid.

I have found it gets very hot, it has an automatic window opener on it, but  I find it is hotter then I can ever remember my glass ones being. However having said that it is hotter here than in the UK although I have had glass ones here as well.

I also find it not as clear as my glass ones so when inside I feel a bit fenced in.

If I had a choice, I would choose glass, but we are not allowed glass on our site.

My  advice would be to ask a lot of folks and don't decide in a hurry.

XX Jeannine

[Alex133]

I inherited a lovely wood and glass greenhouse, probably at least 30 years old now and, with care, will probably last another 30. Bought a polycarbonate/metal one 2 years ago and have to keep patching to stop panels falling out when it's windy, suspect won't be much cop in the long run.

In growing terms find polycarb much 'sweatier' - brilliant for cucumber but doubt tomatoes would do so well (they stay in glasshouse).
 

[Vinlander]

I suspect (like everyone else) that getting the temps right is the key because plastic behaves differently from glass.

I think I read that glass is warmer in cool conditions but plastic can be warmer in hot ones - ?

They behave differently with condensation too - plastic forms big drips that land on your head - glass is more likely to mist over initially and then run down to the bottom.

As to PolyCarbonate there is one big difference - it doesn't let any UV ultraviolet through - but the only plants I know of that notice are desert cacti and the biggest climbing jungle cacti that climb out the tops of trees - they definitely grow more slowly under PC - but other smaller jungle cacti (epis) don't seem to care because they expect to be under the tree canopy.

Most plants adapted for Europe are happy without UV as long as there's lots of visible light.

Whether it affects the flavour of tomatoes ? - well, there's a question - I've never tried growing them to fruit under PC.

Cheers.

[Chrispy]

Do you have a vent low down to let the cooler air in when the hot air goes out the top vent?