Andy,
I find that when the ends of the silks on the cobs have withered
and died if you peel back the outer leaves carefully on the cob you can
examine the corn. Squeeze a couple of grains between your fingernails, the
liquid should be creamy for picking, if watery then you are too early! You
can also tell by examining the colour of the grains, they should be "golden
yellow" rather than whiteish yellow.
My own cobs are usually ready nearer October ( I live on the East Coast
of Scotland),

David
"Andy Hunt" wrote in message
...
How can I tell when my sweetcorn are ready for picking?

Thanks in advance!

Andy