"David wrote in message

P.S. there are a couple of small orange/brown thingies whizzing about but
it
is windy today and they don't stay still long enough to identify.

Yes, that's what we have seen on our allotment, Small Skipper I think, but
it could be Essex Skippers.

P.P.S. I am contemplating a Nettle Bed for the larvae, but nettles are
even
more invasive than mint - anyone have a strategy for containing them?

Plant in a large bucket with the bottom cut out and burried up to the rim,
or use some builders damp proof course material dug into the soil to form a
barrier to the roots around where you want it to stay .

--
Bob

www.pooleygreengrowers.org.uk/ about an Allotment site in
Runnymede fighting for it's existence.