Brassica plants were getting large, so I needed to do something about netting them against Cabbage White Butterfly.
I bought some Debris Netting off eBay [although it came from Tarpaflex]. I selected 3M width as my raised beds are 4′ wide – so that means a clear height of “(3 metres – 4 feet) / 2 in inches” which Google tells me is 35 inches.
I had a roll of 1/2″ Blue MDPE underground water pipe (the Black above ground pipe would be better, as it has UV resistance), so I cut that into 3 Metre lengths, less about 6″ to be able to anchor it down, and stuck some canes in (I cut some 4 foot canes in half, about 2 foot pushed into the ground, and 2 foot sticking out to put the pipe onto. One “hoop” every 6 feet, or so.
The job only took a few minutes, much easier than I expected.

Brassica Netting - Materials

Brassica Netting - Pipe Cut into Section

Brassica Netting - Pipe Pushed on to Canes

Brassica Netting - Net Placed over Pipes

Brassica Planting under the Netting

Brassica Netting - Done
Update:
Go for Black – I thought Green would blend in – it doesn’t!
I use enviromesh for my Carrots (carrot fly is smaller)
In Winter I replace the Debris netting with a wider mesh netting (about 2″ squares) to keep the birds off – the fine mesh of Debris Netting holds the snow and thus the whole structure collapses and squishes the plants underneath. I use the wider 2″ mesh netting in Summer over crops that just need the birds kept off such as Peas, but you could use Debris Netting for them too. I haven’t noticed any problem with light reduction because of the relatively fine-weave of Debris Netting, but it is also used to “throw” over greenhouses to provide some shading.
I also “throw” debris netting over the Strawberry bed (but not until they have finished flowering – mustn’t prevent the insects getting to the flowers to pollinate them), this saves me having to erect hoops over the Strawberry bed, and its very easy to pull aside for picking, and then put back again – just a few bricks around the edge to anchor it down.