South west facing border ideas please!!

I have an already existing south west facing border at 5m wide and 1.5m deep. I am looking to obtain a more structured and colourful all year round display. The plants I already have and would like to keep are: 2x red robins (one veriagated) , 1 lupin, purple alliums, purple/blue hibiscus, hosta, camellia, lavender, echnachia, and a rudibekia. 

I definitely want a lot colour all year round so if you could tell me what to use for spring , summer, autumn. 

Please could you tell me what to put in , where and with what? 

Also any suggestions for evergreens to take me through the winter and add structure.

Hope you can help