Originally Posted by White Gardens
One thing to keep in mind is that with no edging on that area, you have plenty of room to play with, so don't let yourself be confined to the space that is there already.
Personally, I'd stick some evergreens of varying color in there for year round interest and hardiness. Looks like enough sunlight to get away with it.
Plenty of low growing, dwarf and pygmy varieties of evergreens out there. Just need to go to one of your suppliers and see what they have in stock. Even a topiary would make the area pop.
The only X-factor I would put in there is a taller, conical evergreen such as a green emerald arb or similar. In situations like this I like to add one taller plant to offset the boulder, and give the area a little height.
Here is a design I did recently with the same idea. Though I have some perennial flowers mixed in, but you get the jist.