I have a 180 degree turn in my uphill driveway where I am building a low rock wall to keep people from cutting the corner too sharp and eroding the hillside. I want to plant about 3 bushes behind the wall to help make the low wall more visible. I live in Tennessee with hot summers in the 90's and winter lows in the teens. The proposed planting area is in full sun all day with no shade at all. I'd like to plant something that will be around 1 1/2 to 2 feet tall, stay green all year (for visibility) and ideally have some kind of blooms in the summer. Are there any plants that fit that description that would survive in this climate and also do well in full sun? We have a lot of roses around the property and I thought about perhaps doing more of them, but I'd kind of like something that keeps a few more leaves through the winter. Would love to hear any thoughts y'all might have, as I'm just stumped!