"Broadback" wrote
You left them in the ground too long.

Thanks Bob, slaps wrist, must not do that again!

Easily done and not all come ready at the same time especially if you grow
different varieties, no doubt the cloves in the heads are also beginning to
separate.
Once the leaves have started to brown at the tips we always dig up one or so
to see if it's ready, it's not wasted as you can use it "green". After a
few years you kinda get a feel for it. :-)

--
Regards
Bob
In Runnymede, 17 miles West of London