To net or not to net

our  brassicas got destroyed by them white flappy things  so net them , onions and all that lot should do fine even better, net the whole garden 

Cabbage white butterflies get everywhere including gardens, and wherever I have grown brassicas, even in a school playing field, nets have been essential unless you want to hand pick caterpillars virtually daily.

Carrots though are a different matter. In the school field, and in my daughter's windy hill top garden, carrot fly never appeared, whereas in the densely grown area of our allotment site they are a major pest and without enviromesh I would not have any kind of edible crop. I also net parsnips in the same way.

If there are no other carrots being grown nearby, it is likely that there would be minimal damage --- your call though tbh 

Would I know if I had a problem with carrot flly before it's too late? 

Unfortunately no.  If you have the enviromesh to spare, then deffo cover the carrots 

Steve it gets worse.

When you use enviromesh I would avoid making a walk in frame for brassica as white fly can get through the mesh and ruin your sprouts etc. It tends to get a tad warmer within the cage and there is less wind too so the white fly love it.  If you lay the enviromesh on top of the crop and let them push it up as they grow it tends to deter white fly.

With carrots I use a small frame about 3' high so that it is easy to remove the mesh without damaging the crop (especially when they are young) as carrots need regular weeding and you have to keep taking the mesh off to get at them. Those strawberry frames with round rubber balls for corners are good because the mesh just slides on and off easily. They may be expensive for what they do in the first year but they will last years and it's a good investment for the clean crops you get, every year therafter.

I don't bother with netting for anything except peas and brassicas. I rarely grow  carrots even with enviro mesh they still seemed to be attacked. Probably best approach is to grow carrots in very high beds/tubs.

Cheers HH

Newsteve mentioned his plot was in his back garden.
I would buy enviromesh if you can afford it. Lasts longer than fleece, and is useful for many crops. I would use it on carrots, brassicas and young crops to protect them from winds and bad weather.