Plant suggestion for south facing planter

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I have a tall square planter next to my south facing front door. It currently contains a juniper skyrocket (maybe 1-2 years old, 3ft tall?)
I’d like to add something that’s colourful, not too tall, good with plenty of sunshine. Any suggestions?

Is there definitely space for something else? What sort of thing are you thinking of? The garden centres are full of bedding plants at the moment - colourful but summer only. Or are you looking for something a bit more permanent?

Are you looking for something trailing? Maybe something blue to go with the juniper berries? (if it gets berries)

My preference is something permanent and minimal effort (the rest of my garden needs a lot of attention so I want something easy for by the front door).
Im open to bulbs if there’s some spring/summer ones people can recommend.
Something trailing could be an option, is there a trailing variant of rosemary or thyme that is evergreen?