I have been meaning to do something like this for a while and finally saw a simple wooden box that I thought would fit the bill. I bought a sack of alpine grit from B&M stores which at £4.00 was a good price, and the box was from Hexton - I think I paid £5.
I mixed the grit with the compost and once planted added a layer on the top. I am hoping it won't want much watering :).
Here are a few more flowers around the garden.
Rose - Pretty Polly
Perennial Wallflower - Bowles Mauve, it just want to flower and flower :)
The first Cosmos out today
Osteospermum - loves to flower in the sun