East Lothian,
United Kingdom 
Q1.I have what looks like very rich, good compost which is from some grass cuttings but also uncooked household waste e.g. vegetable peelings, outside leaves of cabbages, pea and bean pods, skins of fruit, egg shells and tea leaves and coffee grounds etc. It looks as if it should be very good for all plants but would there be plants that I should not use it for? I have not used it for ericaceous plants but is there anything else I should avoid using it on? What is it likely to be particularly good for?
Q2. I would like to grow plants in this (photo attached) west facing stone wall. I would obviously have to remove some of the pointing but how much would I have to remove, what kind of growing material would I have to put in to establish plants and what kind of plants would it be best to start with?
Answers to these questions may be a tall order and perhaps I need a gardening school! but I would be very grateful for any advice.
Thanks for all the help I have received so far from this website.
SG
4 Oct, 2011
Answers
In answer to Q2 first, on no account remove mortar from that wall - its sound and solid and quite beautiful currently, and making holes in it will mean its no longer in that state - not to mention that you'd need to make pretty big holes to get soil into to plant anything in. If, over time, cracks and gaps appear, various plants will grow out of it all by themselves. I'd do exactly what Louise advises - grow something up it instead.
Q1 - add the compost to your borders, either as a mulch or when you're turning the soil over -it will increase the fertility of the soil and is very useful anywhere on open ground.
4 Oct, 2011
Like Louise I think you'll have a hard time chipping out pockets to fill with soil and any plants you put into them will have to like an alkaline soil because of the lime in the mortar.
Your compost would be ideal for your vegetable garden.
4 Oct, 2011
Thanks to everyone. I think the wall is beautiful too but thought the odd small planting might enhance it. Once saw a garden in Herefordshire where the wall was beautifully planted but that may have happened naturally. However I will leave it alone and train a what promises to be a very good wisteria along it. It's out of the picture but to the right. Sadly I don't have a vegetable garden. Garden too small; flowers and shrubs (bird friendly and insect friendly) have taken precedence apart from the odd runner bean. I'll use the compost on borders and on non-ericaceous borders.
Thanks again
SG
4 Oct, 2011
Re: Q1.
That will be used for planting trees and shrubs but a lot of perennials need a thinner more impoverished soil so i'd not use it on that type of plant.
Re; Q2.
I'm not sure that tapping out bits of that mortar is possible is it, it looks strong !
If you were to plant it up you'd need to allow room/space for some soil to be pushed into the holes/cracks/crevices.
Plants such as a low growing (ground cover) campanula and sedums would get a grip there.
I like the wall as it is is and i'd attach wires to it and grow climbing roses and clematis to it and let them wander across it.
4 Oct, 2011