"Nick Maclaren" wrote in message
...

snip The trouble is that many indicators - such as those two - are very
unreliable. SOME are reliable, such as rhododendron woods or wild
juniper

Aha!
That explains why I got away with "bunging blueberries straight in the
soil" - we've got rhododenrons growing wild 200 yards below our plot!
(It may also explain why my brussels and cauliflowers were so
disappointing?)