I’ve found broadleaf weed killer to be the most effective ... Heal-all produces tall, cone-shaped clusters of small, purple or pink flowers on the top of single stems with oval, serrated leaves.

Moss phlox (Phlox subulata) will smother weeds by forming a thick layer of pink flowers and green foliage. You can also find varieties with blue, purple, or red flowers. Moss phlox is easy to grow ...