Something like nasturtium to grow in shallow soil on top of a wall

[Scrowy]

We always have nasturtiums in the shallow beds on top of the garden walls for a bit of colour around the farm, but I'm looking for a bit of a change. I did successfully manage to grow sweet peas in the same bit last year but didn't really have time for the maintainence of them so they ran away from me, and will I have even less time this year. So it needs to be easy, although I won't rule out trailing/creeping plants entirely. However, they also got eaten by the sheep DP decided to put on the bit of grass next to the garden and the chances of that happening again is extremely high so ideally nothing too expensive or poisonous to sheep.

Between 2 - 4 inches of soil in depth, mainly south facing and sheltered but a good 1300ft above sea level and in the far far north so temps don't get that high and we tend to be a few weeks behind the rest of the uk - e.g the daffodils are only just starting to peek out now.

Grr it's going to be nasturtiums isn't it?

Weeell I was thinking Mexican Fleabane
www.rhs.org.uk/Plants/32487/i-Erigeron-karvinskianus-i/Details

but I don't know whether it's ok for sheep ,Probably not ,a quick google says toxic for cats and dogs
www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/fleabane

Aubretia

The small varieties of dianthus are lovely and flower for ages. I've got one called 'Flashing Lights' that is crimson.

Saxifrage will also do really well in that position and will have low springy foliage all year round.

The small species of campanula are happy in shallow soil as well.

alyssum and creeping jenny (the lime green one) would look nice together on a wall.

How about talking fuschia?

Or even trailing fuschia

Trailing Rosemary (Rosmarinus officialnalis Prostratus).

Evergreen, pure blue flowers in spring. Bees love it.

Ready-seasoned sheep if they dare!

You could always add a few nasturtiums as well.

Ours grow well on top of a wall at altitude.

Thanks everyone some great ideas.

I might try a mix of the suggestions and see what works, there's about 15 metres of wall to cover so plenty of space!

I should have remembered really I was ideally trying to avoid aubretia and campanula as I already have lots and lots of it growing everywhere else out of all the other walls (someone in the farm's past decided to put planted walls everywhere and as a result they are almost seen as weeds here), BUT it has made me rethink that it perhaps would be worth putting some it as a bit of general filler for the years where I don't get round to doing something a bit different.