"David.WE.Roberts" wrote
I've sown some old greyhound cabbage seeds in trays to see if they
were still viable and have had a few germinate.

So I had perhaps 6-8 seedlings in two mushroom trays (the brown ones
you buy mushrooms in) out on a shelf down the garden, waiting to be
planted out.

Yesterday they were surrounded by a crowd of cabbage white
butterflies, and the tiny leaves were covered top and bottom with
little white posts which I assume are eggs.
[...]
I am seriously considering doing the same because nothing is worse
than putting in a load of work and a load of plants just to see them
all eaten.

Oh dear. I know the feeling. My broccoli plants kept getting eaten into
green lace each year, despite the usual net, so this time I've made a
cage with brand new netting which is smaller gauge (5x7mm) and so far
they've not been able to shimmy their way through, despite trying hard.
I remembered to put cardboard collars to defeat cabbage root fly too,
which was another pest that attacked last year.

There does seem to be a sudden huge increase in white butterfly numbers
over the last few days. The garden's alive with them atm; they seem to
be partial to Scabious or Lavender flowers when they can't get
brassicas.

--
Sue