Mesh Tunnel

I had my first growing season last year - great success other than losing all cauliflowers & much of broccoli to Cabbage White caterpillars.
So this year intend putting up a protection tunnel.

I have 3 large raised beds as my Veg plots (about 40sqm growing area) .. and have thought about following this example in a couple of parts of the beds.
Brassica Netting – against Cabbage White Butterfly « K’s Garden

First question is how high should I make the tunnel ? .. thinking that for broccoli I need to allow at least 0.9m high
Should I think about a lower height one for cabbage & cauliflower .. perhaps 0.6m high.

The beds are 1.5m wide so will have good width under the tunnel.


In the url above the diy'er used bamboo stakes ... anybody got any alternative ideas for stakes?


Finally had been intending to do this with enviromesh (so water penetration ) ... would it be worth laying a fleece blanket over plantings (under the tunnel) until we hit end of May, and then remove fleece?

Ideas welcome

 

Hi Sargan,

This is more Kristan & Johns territory as I tend to grow my brassicas over winter to avoid the babbage whites.

I do know that its not good to have any leaves touching the mesh as the little darlings will lay their eggs thru it.

 

Scaffolders' Debris netting and water pipe hoops - much cheaper than netting from the garden centre (and the holes have to be very small to stop the butterflies getting through

There are some pictures of a 9-year-old erecting it on my blog!
http://kgarden.wordpress.com/2009/05/04/brassica-netting-against-cabbage-white-butterfly/

I get about one or two "intrusions" a year - which is good enough for me. Soem people sow-up the eyelettes, and try to keep the netting off the leaves, but I have not found it a big enough problem to actually worry about (but some vigilance is called for)

Debris netting is often "skipped" when the scaffolding comes down, so you might be able to blag some from a building site locally.

 

Hehe...thats the same link Sargan got it from.

Sargan, if you follow Kristens advice the first paragraph on his blog works out the height for you = 35"..or 3 foot.

I'm using the same method myself this year. Its in widespread use on quite a few plot's at my local allotments.

Steve...

*If you buy a full roll of this debris netting you can use it for other crop protection too...and its great for a windbreak too which is what I will be using the excess for.

 

Hahaha ... brilliant!

1. Open mouth
2. Insert foot

 

Welcome to my world ! :D

Steve...

 

Yep ... link to your blog was in my post (thanks) ...It was your 'diy' approach that stated me on this... have just bought black 25mm pipe to do it.

I obviously have to consider height .. before I go cutting all the hoops from the roll.

Does 900 mm for Broccoli patch ... and 600mm for Cauli & cabbage patch sound about right ?

In your blog you show it weighted down with bricks .. is that all you used finally ? ... or did you cover with soil ?

Did you push pipes into ground as well as over stakes or do they just 'rest' on ground.

 

Yup, but I made mine all the same size so that they are interchangeable - but I have 4' wide beds, so basically I just need to cover 4' width - I don't have single-rows or any other shapes to contend with.

Yup, just bricks. Makes it easy to lift up to weed or harvest ... but not very eye-catching if that is important to you. Nothing has tried to clamber under the netting (we have rabbit netting round the plot perimeter)

If I ever get around to putting wood boards around my raised beds I might put some sort of "clips" to hold the netting edges to the boards.

My wife tells me that the slightly-blue-shade-of-green is an awful colour for the netting (I bought "green" and assumed it would be a "blend in green" ... so you might want to choose Black perhaps ...)

The canes are about 4" in the soil (bit more maybe) and 4" out. Pipes are just over the canes . The canes seem to hold them in place just fine (but collapse with Winter snow weight, which is no bad thing - I don't have a Plan B in that scenario! the netting is there in the winter to keep the pigeons off)

 

I'll admit I read it a few times but could not follow it .. (obvioulsy me)

My beds are 52" wide ... how does the maths work for 36" high and 24" high hoops ?

[hr]
I just tried to follow this again, and I'm losing it ...

3m-48" / 2 = height ... where does this formula come from ?

remembering back ... circumference is 2 x pi x r
is it related to this ?


or maybe I was just reading too much into it ... is it just that you had the 3m width already and cut the pipe to 2.7m (6" off either end to weigh it down)

 

Netting is 3M wide

My beds are 48" wide

I assume a "square" rather than "round" profile (for simplicity)

3M - 48" is the width of the netting, less the width of the bed. That leaves you with 1.78 M / 70 inches.

That's the amount available for the "sides". there are two sides, so halve it to get the maximum height for the sides - i.e. 89cm or 35"

So we have:

( [Width of roll] - [Width of bed to be covered] ) / 2

gives the "clearance height"

The length of the hoops you need is dependent on the amount of "skirt" you need on each side

[Width of roll] - ( [width of skirt on one side] * 2)

so say you allow 6" "skirt" on each side that's

3M - (6" * 2) = 2.69M

In fact, we need to allow for the width of the skirt in the formula above

the "clearance height" is:

( [Width of roll] - ( [width of skirt on one side] * 2) - [Width of bed to be covered] ) / 2

 

OK ... let me try 3m roll = 118"

118-(6 x 2) -48 =
divide by 2 = 30"

so if I cut pipe to 106" 118 - (2 x 6")
On a 48" bed I'm going to have 30" clearnace.

[hr]
Have the pipe .. and think I now follow size to cut it to
so need to go buy mesh ....

Looked at:
http://www.gardening-naturally.com/acatalog/Enviromesh_Insect_Netting.html

I read that the standard butterfly net can still allow the blighters to lay eggs through the mesh ... if leaves are close ...
should I be looking to buy ultrafine - or enviromesh

or something else entirely

 

Enviromesh will keep out greenfly as well as larger pests so long as you keep the leaves clear of the mesh.

 

For Cabbage White then Scaffolders Debris Netting would do - 55p per Metre for 2M width

http://www.tarpaflex.co.uk/acatalog/Debris_Netting.html

For Carrot Fly you need enviromesh. I have both (using the same style hoops) £2.14 per Metre for 2M width (also based on 50M length)

http://www.gardening-naturally.com/acatalog/Enviromesh.html

(Their butterfly netting is £1.01 / Metre - however, they have a lot of different sizes / options compared to "Debris Netting )

 

Thnaks for all this help .... just to check, you have you had any issue with water not passing through debris mesh ? ... I only ask as on one Debris Mesh web site ... it says it "provides workers with protection from rain"

 

Nope, not had a problem. I expect as a vertical wall it will make the water run down, rather than "in", but as a horizontal sheet the water definitely goes through it.

Although I think that any fine mesh will have a tendancy for rain to run down any slope, rather than through it