However, there are a few annuals that fit in quite well with this type of landscape. Dianthus is available in shades of white, pink, and red. Dianthus is in the carnation family and has the clumping habit that works well in rock gardens. If dianthus is planted in a protected area, it frequently will overwinter. It also benefits from deadheading during the summer to keep it blooming.
Flowers are very small and white.
It is excellent as a border or accent plant for rock gardens. It prefers a sunny, dry, and well-drained location. It will bloom all summer long. Portulaca , or moss rose, is a very showy annual that is available in a rainbow of colors. A very low growing plant, it is perfect for warm, dry areas such as might be found in a rock or alpine garden.