It's hard to say what's going to work without knowing (generally) what climate you are located in. And where exactly are the rocks?

Dainty alpine plants are perfect for adorning a rock formation, thus creating a wonderful focal point for a garden.

not sure I see a huge rock formation. Is that it in the far back right?

rocks can be great accents in themselves. Are you wanting to cover it up or what?

It's rather interesting that your question is about designing around an existing rock outcrop, but you instead barely show it in your one photo, which mostly emphasizes the existing plants! The railroad ties don't necessarily detract from a unified garden setting IMO, and the question is a bit vague as to the overall space to be considered, and how one might design with regard to the rock outcrop. You could emphasize it, hide it, add more boulders to repeat it; depending on your preferences, More photos of the yard from other angles, photos from major interior rooms/views if important, and your preferences for what you want a redesign to accomplish would be helpful. So far, you've listed unity of design, and utilizing some existing plants in any redesign, and doing "something" with regard to the rock outcrop.

Not really enough to go on here, so I personally couldn't offer any suggestions beyond giving out more information, and better elaborating what you want/need.

It's rather interesting that your question is about designing around an existing rock outcrop, but you instead barely show it in your one photo, which mostly emphasizes the existing plants! The railroad ties don't necessarily detract from a unified garden setting IMO, and the question is a bit vague as to the overall space to be considered, and how one might design with regard to the rock outcrop. You could emphasize it, hide it, add more boulders to repeat it; depending on your preferences, More photos of the yard from other angles, photos from major interior rooms/views if important, and your preferences for what you want a redesign to accomplish would be helpful. So far, you've listed unity of design, and utilizing some existing plants in any redesign, and doing "something" with regard to the rock outcrop.

Not really enough to go on here, so I personally couldn't offer any suggestions beyond giving out more information, and better elaborating what you want/need.

I'm going to say it before Yaardvark gets here (LOL) - back up and take a new picture, providing us with an overall view so we can see what's going on.

I don't see a rock pile either. All I see is a hosta garden.

From what I can see I don't think boxwood would be good for the rock formation. If you stand in front of your house and take a picture facing left, facing right, facing center, all from that same position, you will get some awesome advice.

"I'm going to say it before Yaardvark gets here (LOL)..." Funny you should say. I made a post about exactly that yesterday but neglected to push "submit" before being distracted elsewhere.