In article , Steve
Harris writes
I have some shady redundant concrete areas and I was wondering about
making raised beds directly on them? These, I realise might have poor
drainage

No - unless you waterproofed the bed sides and the join with the
concrete, your drainage would be good and you would hav a lot of
problems with the bed drying out.

but the main problem I have here is extremely well drained
sandy soil.

So, could I then grow plants that love damp and shady places?

Or would I just have dry but poorly drained soil which I've never seen
specified as what any plant wants!

Line your beds with pond liner with just enough drainage holes to
prevent complete waterlogging (perhaps with drainage holes in the sides
rather than the bottom so you keep a reservoir)? Fill with a coir based
compost. Then you should be able to get damp shade which will widen your
choices a lot. You'd probably still need to water at intervals in the
summer so think about incorporating an automatic system or a drip feed
from a water butt, or at the very least some vertical pieces of pipe so
you can get water to the bottom rather than the top. Oh, and you might
want to experiment with water retaining granules like you can use in
hanging baskets.
--
Kay Easton

Edward's earthworm page:
http://www.scarboro.demon.co.uk/edward/index.htm