Topic: whats the difference?

[thifasmom]

Between greenhouses and polytunnels, what i mean is, i know they both give you a longer warmer growing environment, but why do plants seem to really thrive in a polytunnel during the winter months and those in the greenhouse would only really do so if it is kept heated.

is plastic so much more insulating than glass? or are there other factors at work here? can someone make this clearer for me please?

[GrannieAnnie]

Plants like diffused light. No hot spots.

People often grow things in elevated pots in the greenhouse which subjects the roots to wilder and more rapid  fluctuations in temps in an unheated greenhouse than plants in the ground in a polytunnel.
Those are 2 possibilities. That said, I'm trying to build a greenhouse instead of a polytunnel because it will (possibly) look better from the house. My hubby thinks it'll be a shack!
Now I'm thinking perhaps I should try a homemade polytunnel as well for "scientific reasons" :D

[thifasmom]

yes your point sounds plausible, anyone else has any other explanations. and my OH is always passing judgement on my DIY creations too, but is never around to build anything for me or either takes for ever to build what i asked for ::).

[valmarg]

I think polytunnels are quite a bit cheaper than greenhouses.

In Winter a greenhouse would be lined with bubble wrap to keep the heat in, so it would not necessarily need to be kept heated.

We have a greenhouse, and do not keep it heated throughout the Winter.  We have a heated mat (which we call the electric blanket), and a soil warming cable with hoops over it to drape fleece over to keep the heat in, which OH (aka Heath Robinson) made.  It may have been cobbled together, but it works perfectly. ;D

Given the choice, I would always go for greenhouse.

valmarg

[Bean_Queen]

Polytunnels tend to rip a lot, don't they?

[asbean]

They don't rip by themselves!  We are very careful round ours, and a few times we've had near misses with canes, strimmers, hoes and cigarette ends.  I bought a roll of repair tape (which is stronger than the polythene) when we put up the tunnel and haven't had to use it yet (we've had it just over a year).

The most likely cause of rips could be flying objects when we have gales - there are a few sheds around and pieces of this and that which could easily blow over and damage the polythene, but that's a risk you hve to take.

All in all we're delighted with it, now it is filled with new potatoes for Christmas, our tender patio plants and salad leaves.

[shaun01]

and they seem to blow down in the winter mmmm ;D id sooner replace a pain of glass tho then a full cover  ;)that's the only trouble but they are very good on the growing side :)

[asbean]

Ours is going to have to have a tropical storm to blow it away. We have got the strongest combination of frame and polythene possible.  :) :) :)

[manicscousers]

and they seem to blow down in the winter mmmm ;D id sooner replace a pain of glass tho then a full cover  ;)that's the only trouble but they are very good on the growing side :)

had ours 5 years now, never blown down..we've caught it with sharp tools occasonally, we use repair tape..wouldn't be without it  ;D
I prefer it so much, I'm giving my greenhouse away, the light is more diffuse and the plants don't sem to scorch as easily