Alpine aster (Aster alpinus) - A low-growing plant with daisy-like flowers in shades of purple, blue, and pink.
Blue fescue (Festuca glauca) - A tufted grass with blue-green foliage that creates a soft, mounding effect.
Creeping phlox (Phlox subulata) - A groundcover plant with delicate pink, purple, or white flowers.
Dwarf Japanese garden juniper (Juniperus procumbens 'Nana') - A low-growing evergreen with a spreading habit and blue-green needles.
Dwarf stonecrop (Sedum album 'Coral Carpet') - A low-growing succulent with white, star-shaped flowers and pinkish-red foliage.
Golden creeping Jenny (Lysimachia nummularia 'Aurea') - A groundcover with bright yellow-green leaves and small, yellow flowers.
Hens-and-chicks (Sempervivum tectorum) - A succulent with rosettes of fleshy leaves in shades of green, red, or brown.
Iris reticulata - A small, early-blooming iris with purple, blue, or white flowers.
Lewisia cotyledon - A compact plant with rosettes of fleshy leaves and pink, orange, or white flowers.
Mountain sandwort (Arenaria montana) - A low-growing plant with tiny white flowers and silvery-green foliage.
Partridge feather (Tanacetum densum ssp. amani) - A low-growing plant with silver-gray foliage and yellow button-like flowers.
Penstemon procerus - A compact plant with blue, pink, or white flowers and lance-shaped foliage.
Purple ice plant (Delosperma cooperi) - A low-growing succulent with bright pink or purple flowers.
Rock cress (Arabis caucasica) - A mat-forming plant with white or pink flowers.
Rock jasmine (Androsace sarmentosa) - A tiny plant with rosettes of green leaves and small white or pink flowers.
Saxifraga - A genus of plants with a variety of foliage and flower colors. Popular species for rock gardens include Saxifraga x arendsii and Saxifraga oppositifolia.
Sea thrift (Armeria maritima) - A clumping plant with pink or white flowers on tall stems.
Silver mound artemisia (Artemisia schmidtiana 'Silver Mound') - A low-growing plant with silver-gray foliage.
Snow in summer (Cerastium tomentosum) - A groundcover with silver-gray foliage and tiny white flowers.
Spanish oregano (Origanum rotundifolium) - A compact plant with purple-pink flowers and aromatic leaves.
Stonecrop (Sedum spectabile) - A succulent with pink or red flowers and blue-green foliage.
Thyme (Thymus spp.) - A low-growing herb with fragrant leaves and pink or purple flowers.
Tufted hair grass (Deschampsia cespitosa) - A clumping grass with delicate, airy seed heads and green foliage.
Yellow alyssum (Aurinia saxatilis) - A low-growing plant with yellow flowers and gray-green foliage.
Yellow stonecrop (Sedum kamtschaticum) - A low-growing succulent with yellow flowers and green

Rareplant.me Top 25 Plants for a Stunning Rock Garden