Polytunnel growing v outside growing

[ojay54]

I agree with the general tenet of all this,in terms of pest control,ease of management etc the tunnel offers a lot.It wouldn't do for me to not garden outside as well.For everyday you get cosy and dry in the tunnel,there's a boiling hot one where you'd rather be outside.

[Green Aura]

Without ours we'd be lost. There's not much we can grow outside up here, so I tend to count our polytunnel as "outdoors under a huge cloche. It does get mighty hot some days though - 40+ on sunny days.

I don't know how you manage to keep it snail free though, Tony. We chuck loads out, every day. We've even bought a tank with a view to harvesting them, there are so many of the little buggers. Not that we've got round to using it yet.

However, I seem to have largely cleared it of spiders - I keep bringing them into the house in my hair!

[Odsox]

I'm the same Maggie, without my tunnels I certainly wouldn't be self sufficient in vegetables, although I still grow potatoes and maincrop peas outside.
Snails are not a problem, the odd ones I do find are those big ones and they are normally very helpful by resting on the polythene cover where I can easily pick them off to feed to the chicken. Slugs are still very much reduced since I dosed both tunnels with a course of nematodes a few years ago, that plus my tunnel residing robin and the copper rings have stopped them totally from getting into broccoli and cauliflowers.

[ojay54]

[quote="Green Aura"]

I don't know how you manage to keep it snail free though, Tony. We chuck loads out, every day


What about a moat?

[Odsox]

Some day when I get around to it, I'm going to install a copper threshold strip on all my tunnel doorways. As my polythene is buried all round that's the only way they can get in, so slugs and snails should eventually die out inside with no replacements.

[Green Aura]

One thing I've noticed though, growing strawberries in the polytunnel is not so good. It gets too hot and they don't flower, just put on new runners. The one's growing outdoors, in pots, have long since finished. My polytunnel strawberries are currently in full bloom with lots of green strawberries - do you think they'll ripen at this time of year?

[Odsox]

That's the problem with living in tropical Scotland Maggie

Those strawberries I commented on in the Harvesting thread have been basking in 30c plus for most of that wonderful summer we had, so I don't think it's the heat. Mine of course are in the greenhouse but they are also in the hydroponics tube, so have ample water 24/7, and I think that might be your problem.
Plants are renown for running to seed if they are stressed and I would think that strawberries throwing runners could be a similar symptom of stress.
So the thing to do is set yourself up a full blown hydro system

Or failing that, maybe copy DND and grow them in a piece of gutter with a constant trickle of water.

Or maybe grow prickly pear cactus instead.

[diggernotdreamer]

Polytunnel growing revolutionised my life 12 years ago. I can't imagine life without a tunnel now. Early strawberries and potatoes in May, clean salad crops (they did really well despite the high temperatures), I grew the Moonlight runners in the tunnel as recommended by Odsox (thank you) and they did really well, I planted them in the bed next to the salads and they offered some welcome shade. I am looking forward to my crop of sweet potatoes, I had a little furtle around in the big pots and there seems to be something going in there. I also have outside beds, 14 x 10ft x 3ft and 3 20ft x 3ft beds for growing spuds, carrots, onions, garlic, parsnips, leeks and all the greens. I need more bed space as I am running out of rotation for the 12 varieties plus of potatoes I grow every year. The strawberries did great in the tunnel, I am planning on extending it now. They do like it moist, I mulched with gravel to keep the moisture in and they didn't stress out

[ojay54]

Most commercial tunnels,admittedly bigger than we are likely to want,nevertheless have some sort of system to move air through the tunnel on still days.This might be worth copying,what do you think?

[Odsox]

Mine automatically do that OJ. Against all "professional" advice, mine are built on a slope because that's the only place I could put them, with the bottom ends about two feet lower than the top ends.
When the inside warms up there is a very strong thermosyphon effect with masses of hot air blasting out of the top doors, being replaced by cooler air at the bottom of course.
I have thermometers either end and the difference can be as much as 10c top to bottom, which is useful for planting melons at the top and cauliflowers at the bottom, for instance.
It's so, so useful I can't understand why tunnel manufacturers don't recommend it.

EDIT: Forgot to add that my tunnels run north/south which accentuates the flow, again this is contrary to the recommended east/west.
All in all, being a rebel seems to pay off sometimes.

[ojay54]

Well you've stole my thunder,'cos that's exactly what I was going to suggest!

Loads of occasions I've seen tunnels set up/down slopes for that very reason (and if we just listened to the professionals,we'd still be paddling around in dug outs.)

edit: Think I'd rather be paddling around in a dug out as it happens....

[diggernotdreamer]

my tunnel runs sort of East to South West, the bottom doors usually get a good breeze as we have the atlantic to the west. When I bought my big tunnel (16 x 72) I also bought a new idea by First Tunnels which is a pipe that runs the entire ridge, it is perforated with lots of holes and the idea is that warm air is sucked up and taken out, probably a bit like thermal syphoning? I don't have electricity to my big tunnel, I looked at those air movers but you need a power supply and to be honest, even on hot days, I think the pipe thingy is working

[Green Aura]

Or maybe grow prickly pear cactus instead.

Don't forget out tunnel is covered with twinwall polycarbonate. And despite umpty mile per hour winds it takes the lot and laughs. Ours is roughly south to north, when we upgraded it we took out the back door at the back but left an open (mesh) window. It too is on a slight slope up to the back. And it does the compost bin sitting behind a power of good

I think the stress you mentioned, Tony, is the vast deviation in temperatures. Just a little sun will make it really warm but the temperature plummets at night (although our heat sink manages to keep it above freezing).