Hi Peter and welcome to GoY. Could you not make a feature of the rock with pockets of soil with plants in them? Trying to cover the whole of the rock face with soil is likely to be unsuccessful I would have thought.

Sounds like a non starter to me unless you want to bury the whole rock several feet deep as otherwise the weather would soon denude it again . If there are any crevices or you were able to remove enough rock to put a small amount of soil in you might try planting sempervivums - they will grow on bare tiles once established.
Are you very near the sea?

Why not make it an "island" in your garden where you can place some potted plants or ornament on it. Could you please mention the dimensions of the rock to give a better idea of what you are dealing with?

Some plants do very well growing in the small cracks & crevices of the rock. I think of Thyme, Ajuga, Chamomile, Snow in Summer & various Sedums. How big of an area is in question? Covering a slab of rock with xfeet of soil is asking for trouble,especially when the heavy rains come. This is what's going on in California with mud slides burying houses & people. Of course in the middle of the night.

Seems like we are all saying the same thing... not a good idea to try and completely cover. Yes, dimensions would be useful and a photo if possible!

Plant around the verges of the bare rock and allow the foliage to creep over the space. Have a look at this site for suggestions. http://www.finegardening.com/covering-ground-creeping-plants. I find that plants attract soil under them where they grow over paths etc. which helps with the problem of soil erosion in places where there is no planting holes available.

Or you could plant a prostrate juniper alongside it.

That is a good idea Steragram because then it will have colour all year. Depending on the size of the rock maybe think of other low growing evergreens. I have a cotoneaster which has grown all along a wall from one planting pocket . It flowers in Spring and has red berries which the birds like in the autumn.

As Peter has not come back to us we are throwing suggestions into a vacuum

Maybe he only uses his computer at weekends Mg. I find that many of us look at the questions and find solutions to our own problems or get ideas inspired by the answers given to and by fellow members.

Cotoneastyer horizontalis is a very good idea too - tough as old boots and feeds the birds as well!it would be nice to know what he decides though wouldn't it?

You can even walk on Cotoneaster horizontalis and it won't harm it! Yes Stera would be good to know what Peter decides to do, Shetland isn't noted for its gardens.

Might harm your ankle though, if yo twisted it between branches, lol.

Nope it is so flat to the ground growing across of of our paths that you wouldn't even notice you were walking on it...