In message
Chris Hogg wrote:

I am digging a pond on the site of an old derelict stone cottage,
taken down some 20 years ago. The soil I'm excavating is obviously
made up, i.e. isn't virgin, has a pH of about 8 and contains a lot of
fine soft friable mortar rubble. I presume this is old lime-mortar, at
least in part, and probably came from the remains of the cottage. I
intend to include a bog garden in part of the pond, on top of the
liner, and the alkalinity of the soil has come as a bit of a surprise,
as we overlie granite and the soil is generally acid.

2. I was thinking of using the remaining soil to make an elevated
rockery for growing alpines, but as yet I have no idea what I might
grow or the soil requirements, other than it should be well drained.
Would an alkaline soil be suitable, at least for some types, and if
so, what? (I've always fancied growing blue gentians but the intended
site faces south with no shade so may be too sunny).


Most alpines will do well at pH 8 except asiatic autumn gentians and
probably lewisias . Gentiana verna / angulosa should be fine. (if you are
on granite you are not in south east England and so have less risk of
drying out). Dianthus will love it as will saxifrages, alpine poppies,
aqualigia etc. As you say well drained with some organic matter.

Enjoy

Paul


--
CTC Right to Ride Representative for Richmond upon Thames