Paint it Black! (channeling the Rolling Stones for you youngsters, lol). The "golden rule", (just to slightly disagree w/Wild West), is more like 3/5 for your focal point (wood, rock or major plant.)..but 1/3's are good too. Just don't do 1/2 and 1/2, it looks really lame & artificial.
I would suggest not mixing those 2 types of "wood", nice as they both are. It can only look forced. Rocks hopefully will echo your substrate...too much contrast is off-putting unless it's by color...to me anyway.