Planting a trough

Hi Guys - can anyone advise what plants I should plant a two brick high trough that runs alongside a patio. Its about 12 foot long and the earth section is about 8" wide. I would like something that I dont need to replant every year and provides flower for as long as possible during the spring summer time. There is nothing in in at the moment apart from cat mess.

 

I don't know where you live Ravy,but if you can get to Harrogate Spring show the alpine gardens are wonderful,have a great time choosing.April24th25th26th.

 

Im right down on the south coast for my sins.