The dreaded "You're an Alpines expert" !! Help please

[robg]

Just because I've given the occasional friend or two a pot of blue poppies or a nice primula I've grown, has promoted me to being an Expert  .

It's happened again and I need some assistance please.  We stayed with friends over night and I was taken round the garden in the morning - quite a competent garden and well maintained, but.... the owner has built a 750mm high dry-stane, retaining wall and wants to put some 'alpines' in it.  The problem is that it is as north facing as it could be, so no sun - open aspect, but no sun.  Can I get some suggestions please ?  I think the term 'alpines' in this context is anything that is small and will cope with a vertical face.  I guess the soil will probably be neutral.

Many thanks
Rob 

[Susan Band]

As long as the plants can get at a decent amount of soil behind it Ramondas and Haberlea should do okay. It is getting access to the soil as there are often big gaps behind the stones.
Susan

[David Shaw]

Stuff like Sedum spathulifolium and mossy saxifrages prefer some sun but will do quite well in the situation you describe.

[JohnnyD]

One solution to the problem of gaps behind the stones is to take old compost - as full of old roots as possible - and ram it as far as a thin stick can push it between the stones. The roots stop it falling away if it should dry out.
It is even better if it is put between the stones as the wall is built.
That way the plants have a decent start.
Try putting seeds in the mix too as they will find their own way to nutrients and moisture and will not be too demanding at the start.
JohnnyD.

[Brian Ellis]

One solution to the problem of gaps behind the stones is to take old compost - as full of old roots as possible - and ram it as far as a thin stick can push it between the stones. The roots stop it falling away if it should dry out.
It is even better if it is put between the stones as the wall is built.
That way the plants have a decent start.
Try putting seeds in the mix too as they will find their own way to nutrients and moisture and will not be too demanding at the start.
JohnnyD.

Excellent solution Johnny

[Martin Baxendale]

Meconopsis cambrica (Welsh Poppy) in its yellow, orange and red variants, while not exactly an alpine will colonise shady dry stone wall and make a superb display - along with ferns of course. It's best to source M. cambrica plants and then allow them to seed about in the wall, or better still collect the fresh seed and sown into cracks in the wall straight away - old seed germinates poorly and bought-in seed seldom does much at all.

[gote]

Various ferns do well. Asplenium septentrionale, trichomanes, adulterinum, ruta muraria and asplenium/scolopendrium whatever we call the harts tounge these days. I assume Athyrium nipponicum will fit the situation as well.
The important thing is of course as has been pointed out that there must be soil without gaps all the way back.
Göte

[Martin Baxendale]

Adiantum venustum, the Himalayan Maidenhair Fern, would be good. It would probably run about in the cracks and behind the stones and pop out all over the place - bone hardy (grows all over my dry garden and not bothered at all my the recent cold) and beautiful.

[JohnnyD]

Too many foliage plants and not enough colour.
Try Aubretia, Arabis, Alyssum and other 'common' wall coverers. They may not give all of their best on a north facing wall but it would be better than all greenery.

JohnnyD

[Martin Baxendale]

The easier campanulas (e.g. carpatica) might be worth a try too. Also lewisias? (should be plenty in the garden centres).

[Nick_the_grief]

Snowdon Lily Lloydia Serotina grown on the north faces of Snowdon .... should cope with a drystone wall