What mesh for tunnels

[Argonaut]

Building some tunnels to protect Brassicas - following this style:
Brassica Netting – against Cabbage White Butterfly « K’s Garden
What mesh should I be using .... looked on :
Enviromesh and Garden Netting

I had read here that cabbage whites can lay eggs through the mesh on normal mesh ... so would I need extra fine or enviromesh ?

Don't want to block water passage.

[Two_Sheds]

Mesh doesn't block rain, don't worry about that.

The mesh needs to be smaller than a folded butterfly, because they WILL squeeze through small gaps

The butterflies will also lay eggs on any net that's touching a leaf, so suspend the mesh a good few inches above your plants

[Kristen]

I get at most a couple of butterflies inside my scaffolders debris netting in a season, and one or two egg-lays. The leaves of my Brassicas are pushing against the netting all along the row by mid Summer. The Cabbage Whites fly around furiously attracted by teh smell ... So although I would not deny the possibility exists in my experience its almost a non-issue.

If you will not be around often enough to be vigilant then you might not be happy that scaffolders debris netting has eyelet holes (or you will sow-them-up!), or you will take care that your netting is tall enough so the leaves of full-grown plants will not touch the netting.

I think Enviromesh is expensive overkill for butterfly protection - but if you only have a short length it won't make much difference, and will also be useful to cover Carrots against Carrot Fly.

Nice you found a link to my blog

[Two_Sheds]

If you're evil/cross enough, plant some verbena bonariensis as butterfly bait - they love it. You can then catch and despatch them before they lay on your crops

[Alison]

I use enviromesh on mine, really brilliant stuff, on it's third year and still like new (allthough not as white as it once was) so although expensive well worth it in my oppinion.