Posted: 30/12/2015 at 12:04
Hi. I take it what you have is a newly cleared and simplified garen with some roses and bare soil that needs filling to keep down weeds and set off the roses and you want to keep it low maintenance.
I suggest you stick to growing dahlias in pots as specimens as they are fairly high maintenance plants - tender, so need lifting every autumn and starting again in a frost free place in spring before planting out after the frosts and they are slug magnets.
Good companions for roses are hardy geraniums which are available in many sizes and colours from white through pink to deep agenda and shades of blue with different leaf shapes and shades too. Not slug fodder either. If you want hot colours such as yellow, orange and red, have a look at geums.
Alliums are bulbs which will give height in late spring and early summer and are supposed to be good at deterring greenfly which might attack your roses. Just plant them in autumn and leave them to do their thing. Add daffodils, crocus, snowdrops and so on to give an extended season of interest.
You can use this facility on the RHS site to help you find plants that are low maintenance and will suit you soil, aspect and colour scheme - https://www.rhs.org.uk/plants/search-form