"Victor Meldrew" wrote in message
...
anything too big (say 20 foot max). We're also a bit concerned about the
roots undermining the greenhouse foundations. Ideally we want something
with an upright shape so that there aren't too many branches overhanging
the greenhouse.
It depends on which side of the greenhouse you put the tree. The sun isn't
directly overhead so shade is cast to one side. If its on the shade side of
the greehouse then if the branches are high enough, the sun will come in
under them. I'd worry more about trees that drop leaves/sap or are prone to
bugs that drop stuff which will get the glass dirty and clog the gutters.

We are planting a tree to block out the towering brick backdrop of a
neighbour's extension so would really like something evergreen but not a
conifer. Once above the greenhouse, the tree would receive full sun in
all seasons but midwinter.
If you're on good terms with your neighbour you could buy him/her a nice
climber of your choice to grow up the wall.

I really fancy a Eucalyptus but haven't seen any that are small enough.
Are there small varieties that are evergreen?
I think you can keep an eucalyptus any size you want by copicing it but
they're very flexible trees and you probably want something quite rigid so
it doesn't bang against the greenhouse in high winds.

Martin