Please help - what should I plant in a border in the top of a wall?

This needs thinking about. I do think that annuals etc are quite high maintenance, so personally I would avoid that.

I’m out in a minute - garden centre😊 but will come back later.
No doubt you will have had loads of suggestions by then.

What depth of soil is there and is the soil acid or alkaline etc?

Dahlias are eye catching and colourful. I have them in raised beds, just watch out for slugs. They are easy enough.

Oh and lupins.

Bergenia (Elephants Ears ). Baby Doll . So good tempered and compact, pretty pink flowers and stays green through the winter. No problems with pests. Non invasive.

Aubretia Kitte Blue.

Campanula muralis. This will tip nicely over the wall.

I'm with Einna for Aubretia too, for very early flowering and they drape down nicely down the wall.

And the Campanula, which has a long season after the Aubretia gets tired.

Both easy peasy manage and not tall enough for you to stop having natters over wall.

Campanula is a must.

For summer if you don't want to water very regularly succulents and other drought resistant plants is really the way to go.

For spring color interplant with bulbs, as they die back tidy up the leaves and they stay dormant until next year

I love the aubretia ans the campanula. Be very watchful with lupins and greenfly.
A few plants of the primrose variety will also give early colour but remember the plants will need split often.

Whitewave, the soil is about 18” deep. It’s been topped up at various times with multi purpose compost so I assume it’s neutral.

I agree with aubretia and campanula, both come in a variety of hues from white to dark pink.
You don’t say how height your raised wall is, so I’m assuming it’s around knee or thighs high. You don’t want to plant anything too tall that would be difficult to manage.
There are several rockery type plants which would give a structure to your bed, in between those you could plant some annuals that are easy to grow.
Examples could be alpine phlox, sedums and Almeria (thrift).
Osteospermum could a bright summer choice, sometimes they last through the winter. Small ornamental grass such as Festuca glauca which is a lovey grey blue and not invasive.
Have fun researching plants and designing your bed.

It’s worth considering rock roses (helianthemum). A small evergreen shrub covered in masses of rose-like flowers in summer. I have several in a north facing bed and they seem to thrive.
A light trim after flowering encourages them to keep going all summer. Attractive foliage in the winter.

Erigeron karvinskianus (Mexican fleabane) forms lovely mounds of pink and white daisies with a very long flowering period. They can be cut right back early in Spring to flower the next year. They self seed but are easily removed if necessary. Enjoy your project, TBW.

Thank you all, you’ve been so much help. I’ve gone from being anxious to looking forward to getting started.

I agree with aubretia and campanula

So do I. Aubretia should be chopped back after flowering but that's easy enough.

Miniature daffodils for the Spring and perhaps some summer bulbs too.

Another vote for Mexican Fleabane Likes it dry and if it does really dry out it recovers with the next shower long flowering period and chop back one a year. Only slight disadvantage self seeds very easily but they pull up easily or break off cracks in paving

So in order for the bed to look good and together, you need to repeat plant.

Personally I’d be very constrained in my planting and even think of a Japanese type of colour palette - so emphasis on greens. I think I would plan gravel and the odd rock with creeping thyme which is beautiful in flower, running over the rocks, or mind your own business, to replace moss which is so difficult to grow. Dwarf pines, dwarf rhododendron, carex are examples of the type of planting.

You will have as many suggestions as people I expect, but whatever you choose will be lovely.

Happy planning

I suggest Aubretia too……..there’s several different colours.

Definitely campanula. You could also get some of those little pots of miniature daffodils, which are already in flower. They'll brighten it up straight away and return every spring. Ditto crocuses and maybe snowdrops. Have fun - you're going to have a flurry of activity now, then you can potter and chat as you wish.

I have some old lavender in troughs and they look really ugly and need replacing.after a few years despite careful pruning.

Another vote for Aubretia and it has variation in colour .
It will not grow in my garden and neither will Nerines . I've tried .
Iberis and Senecio do and I think that the pure white flowers and the silver leaves of these two plants are beautiful together .
I think that most Alpines will grow on top of your wall .
I also suggest miniature bearded iris -not gruwn so frequently and a delight .
They can get lost in a border . I gruw mine in pots.
Miniature roses are pretty too .
The possibilities are endless....
I'd be tempted to sprinkle some Godetia seeds into your border -so pretty and rewarding .

Enjoy your garden .

If you would be happy with profusion, I would recommend Tidal Wave Petunias. They are annuals which flower all summer right until the frosts, but don't need dead-heading. I buy mine every year from J. Parkers on line as garden ready plants. They will cascade over the wall and certainly get comments from passers-by. www.jparkers.co.uk/petunia-climbing-tidal-wave-garden-ready-collection-1

I walk past a house with a wall like yours teabagwoman in all Seasons, and it’s covered in cushions of Aubretia, with lots trailing down the wall.It’s spectacular when the flowers are out but looks good even when just green.Very little maintenance needed I should think.

I imagine that the bed gets very dry in summer as the bed is narrow and with brick either side which will absorb moisture. Also there is not a great depth of soil, so unless you can frequently water in dry spells, go for plants that like dry conditions. All the grey leaved and Mediterranean plants would do well or South African varieties. The list is long so just google drought tolerant plants and give some a try.

You would not want tall plants I imagine but low growing ones that can drape over the walls. Read the plant labels carefully to check height and growing conditions (I am partially sighted so take a small magnifying glass with me). In such a position, robust plants rather than delicate annuals would survive longer

I’d suggest turning it into a herb wall. If you plant hardy herbs such as Rosemary and Thyme these will spread slowly. You could plant Lavender there too. In between the herbs put gravel to stop weeds. Very easy maintenance. We have done this and it has looked good for many years.

We have a wall next to our property. It is the perimeter wall of the house next door which used to be a pub. We have foot access across the front of the house. On top of the wall there were herbs planted, mostly thyme and sage. D H asked permission of the owner to remove the thyme as it was very straggly. He planted house leeks in the wall. They look after themselves and are pretty in the summer.