Cover Vegetable Patch with Polytunnel?

The thought crossed my mind to cover the whole of my vegetable patch with a Polytunnel.

I have only recently noticed people growing seemingly "conventional" crops in Polytunnels - Brassicas and the like.

If I did this it would have to cover all 4 crop rotation beds, so everything would have to be "indoors". I have a further 4 crop rotation beds, on a different system, which could be in, or not.

So are any of these going to perform less well "indoors"?

Brassicas - Sprouts, Sprouting Broccoli, Winter Cabbage
Beans - Runners, Climbing French, Peas
Roots - Carrots, Parsnip, Celeriac
Onion - Onions, Leeks, Garlic

Catch crops - Beetroot, Kohl Rabi, etc. Chinese Greens

Second set of beds:

Asparagus (not rotated, natch!)
Strawberries (rotated only every 3 years, or so)
Spuds
Sweet Peas / Gladioli
Courgettes / Squash
Sweetcorn (already grow an early crop in the greenhouse, this is the "main crop" for late August / September)
Other catch crops - Chard, Lettuce

I suppose if there are just a few crops that will dislike the heat I could keep one or two beds "outdoors" for them.

Irrigation:

I thought that capturing the rain off the roof, into a tank, and then having a drop irrigation system might solve that - along with ground cover woven membrane.

Ventilation:

I would go for roll-up polythene sides (with permanent netting)

1st Tunnels looks to be about £1,500 - £2,000 to cover the main 4 beds

Any other Pros / Cons pls?

 

It would mean a lot of extra watering with no rainfall + the extra heat.

P.S. I thought you'd go for something a bit bigger http://www.ebay.co.uk/itm/121357152873?_trksid=p2055120.m1438.l2649&ssPageName=STRK:MEBIDX:IT

 

I wonder about that. if I collect the rainfall onto the roof (into a tank) and put that back (via leaky hose, say) will it then need more than I would additionally have given the Veg patch during the Summer anyway?

I'm thinking that the tunnel will contain the humidity / evaporation, to a large extent. Maybe the additional heat will cause more evaporation / transpiration and will dry the soil [in that area] more than normal - i.e. it will suck up more ground water, and become drier as a result.

Well ... if it looks like being a good idea I would consider a multi-span tunnel. The cost is not massive (I know it is all relative), and it would give me earlier crops, and easier management of the crops [assuming that the irrigation can be sorted out].

As it happens we are looking at irrigation in general. I so resent using potable water on the garden that we are starting to provide some storage of our own. We have recently replaced our cesspit with a modern digester thingie, the output from that is suitable for irrigation, so goes into the original cesspit, along will all captured roof rainwater, and from the land drains (I am figuring that the multi-chamber construction will allow muck/dirt to settle, and be pumped out occasionally), and if that proves to not be enough storage in its own right then I would be inclined to put in a 100 cu.m. above ground cylindrical corrugated galvanised tank. None of this is affordable, compared to the £1-ish per cu.m. that I buy potable water at, and I would much prefer to spend the money on something else ... but on the one hand I feel strongly about it, and on the other I'd like some safety net next time there is a hosepipe ban.

 

Grow everything in the tunnel through Mypex to reduce evaporation from the soil? (but there's still additional transpiration)

Based on experiences on walking inside when the door & vents have been closed overnight and then the sun's come up and the humidity has knocked me back (you notice it more if you wear specs) then rapidly decreases once the door/vents are opened, I reckon it gets vented out. Must check it out with a hygrometer sometime.

I think that during the last hosepipe bans you could use one to water inside a poly tunnel, but not outside, so erect a poly tunnel over all your plants and you'll be immune from similar hosepipe bans

P.S. I've never really considered this in detail before, but are poly tunnel borders higher maintenance (pests & diseases) than open ground for crop rotation?

 

Yes, that's my plan. Not tried it before, but this year I am growing most veg (only excluding things that were started early in the year before I made my Master Plan ) through Mypex. I'm a detail person, as you all will know , so doing it with a high level of Faff. I have 4' wide raised beds, and I generally plant in a given "spacing style" for a specific crop (so Beetroot is 4 rows along the bed at 9" spacing, and Brussels Sprouts are 3 rows, staggered 30" spacing and so on). So I have cut X's in Mypex at appropriate spacing, and for a reasonable length piece of Mypex (allowing a few more plants than I usually grow for the years when I have a few extras). Labelled each piece, for reuse next year given Crop Rotation etc.

My expectation is that the extra Faff in planting (precision of planting holes etc.) will be offset by no weeding and either less watering, or plants benefiting from less evaporation.

Yes, my greenhouse is the same. I'm always pleased at the humidity in the morning as I figure that the plants are probably enjoying it, and growing more as a consequence. But is it "more" than if they were planted outside, or just "trapped"?

That's fantastic news!!!

My greenhouse beds are less maintenance than open ground. Fewer weed seeds get into the structure. Irrigation is much higher though (I don't, yet, have any automated / plumbed / piped irrigation to the plants in the greenhouse).

 

You betcha - tempted to order one "on-spec"!

Surprising, as they hate cold / chilly nights. Worth knowing, thanks, and mine are in permanent positions (same each year) so would be no bother to provide for them "outdoors"

I grew Climbing French in my greenhouse once, and had that problem (would have been no problem with pollination, compared to Runners, of course ... but even so "too much top"). I wonder why that is, would have expected them to love the heat.

Runners, too, would be happy with a permanent same-position-each-year location, so I don't see them as being a problem. (Presume that is true of Climbing French too, as we prefer them to Runners)

Interesting, thanks. I have a lot of rust on my [autumn planted] Garlic this year, caused by wet Winter / Spring presumably. A tunnel cover would solve that too I expect.

They need support outdoors too - let me assure you of that!!!

What about:

Lettuce? They tend to do less well in the hotter months.

In your salad crops (to which you said "yes") would you include Beetroot, Chard, Kohl Rabi? I don't bother with Spring Onions and Raddish. Trying to think if I grow anything else ...

2nd earlies and salad spuds, in the ground, rather than Bags? I've done bags in conservatory, but only ever for earliest possible crop, and planted 1st week of August for XMas new potatoes so no experience of "Main crop" so to speak.

 

This year I've grown early sown T&M courgette F1 Midnight (seeds bought for 50p/pkt @ 'Wyvale' end of season sale) courgette plants transplanted into 10L pots, then polytunnel grown, then put outside after risk of frosts passed.

 

Interesting Scrungee. I've done "fairly large pots" before, and the planted out, but I can't say I noticed a huge different to normal. You are presumably keeping them in pots (plunged perhaps?)?

Be interesting to know how that goes

 

Sorry to hear about O/H's pelvis

Very helpful info, thanks.

Worth looking at a "Munti Frame" if you are thinking of something semi-permanent. Pretty sure @JWK has constructed one (its an idea which sprung up on another forum)

 

Thanks

I've bought a larger piggy-bank, and tipped the meagre contents of the old one into it ...