12 Beautiful Perennials For Your Sunny Rock Garden

Rock gardens can be both beautiful and useful. We had a rock garden when I was growing up that my dad built for my mom, one rock at a time on a flat empty slab of land. I remember hauling up flat rectangular pieces of slate from a creek bed near a farmhouse we owned briefly, until there were enough to build a low rock wall. Then we filled it in with soil, and added a few strangely shaped rocks as accents. The came flowers, at first mostly annuals my mother selected every spring: snapdragons, portulacas, and petunias were her favorites.

Then as the garden matured, perennials were added: lush but low-maintenance hostas for the shady spots, creeping phlox for the rock wall edges. That rock garden was where I first learned about gardening, and learned to love colorful, fragrant flowers planted together. The neighborhood loved the garden, and people out walking often stopped by to admire the flowers. 

Rock gardens are not only a great way to showcase a design scape of plants and rocks, but they provide a good solution to difficult areas such as slopes or places with natural rock outcroppings. Creeping, spilling, meandering plants are perfect for rock gardens because they can spread over rock surfaces and also fill in crevices and spaces. This list contains plants chosen for their suitability for a rock garden, and a variety of light and climate situations: some of them are sure to be perfect for your space.

Creeping thyme is a low-growing, fragrant flowering herb that is perfect for walkways and rock gardens. It can be planted from seed, and will also reseed from its growing area and come back each year. This plant likes a fair amount of sun but is otherwise not very fussy about soil or other conditions. It can sometimes get a bit leggy, and in dry weather the stems may look dry, but they can be easily sheared off to make way for fresh new growth.

Threadleaf coreopsis is a versatile perennial that has a delicate, airy look in the garden, with lacy green leaves and colorful flowers. It spreads by putting out thin roots and will meander among rocks and other plants, making it a good choice for rock gardens. It likes plenty of sun, and is somewhat drought tolerant. It comes in a wide range of colors including yellow, orange, pink, and red, and many bi-colors. Try 'Moonbeam' (pale yellow flowers), 'Route 66' (yellow with splotches of dark red'), 'Citrine' (bright yellow), or 'Broad Street' (deep reddish orange).

This late summer bloomer adds gorgeous bright blue color to the perennial garden, and has glossy green leaves with deep burgundy accents. It spreads gently via slender roots, and meanders nicely in a rock garden. Also called blue leadwort or peacock plumbago, Ceratostigma plumbaginoides is somewhat slow to wake up in spring and is best divided then, before the plants start to get their summer growth. This plant likes plenty of sun, prefers a sandy, loamy soil, and is fairly drought tolerant.

Candytuft is also known as Iberis sempervirens, and is native to the island of Crete. This fluffy plant comes in shades of white or pink, and puts on a show for weeks in the summer garden. The flowers fill in empty spots beautifully and the spiky green leaves spill over rocks or out of crevices in the rock garden. When the plant matures the stems get woody, and the plant does well if sheared back regularly after flowering is done, to help keep it looking neat and not too leggy.

This beautiful shade-loving ground cover produces tiny, delicate flowers in a range of hues from pink to yellow to orange to white. The leaves are usually oval in shape though some are more slender and come to a point (like those on 'Enchantress,' a cultivar with pale pink flowers). Barrenwort, also known as Epimedium, flowers in mid spring and has glossy green leaves tinged with red that look great all season. It forms roots in a tight mat which deters weeds, so in the rock garden it easily fills in bare areas between large rocks.

Perennial geraniums, also known as cranesbill geraniums, are delicate looking but very hardy flowers that bloom for weeks from late spring to early summer. Shear off the spent flowers and they will put on another show a few weeks later. This plant is great in a rock garden because the stems meander among other plants. The colors of perennial geraniums range from pale pink to deep blue-violet. 'Orion' and 'Johnson's Blue' have vivid blue flowers with lovely long stems that create a flowing tapestry of blooms weaving between and around other plants and rocks.

With their spiky leaves and masses of bright star-shaped flowers in a variety of colors, creeping phlox, also known as moss phlox, put on a dramatic show in the sunny spring garden. They work very well in a rock garden because the plants spread out in a carpet up to two feet from their roots, so they can cover rocky areas nicely. The foliage and stems can get a bit overgrown and dry over time, so shear them back a few inches in the fall to give them a fresh start in the spring.

This low-growing ground cover loves shade and, unlike many other shade ground covers, sweet woodruff spreads very gently and is easy to divide or move if it grows too much. The starburst shape of the leaves and tiny white flowers provide delicate beauty in spring, and the plants give off a soft vanilla-like fragrance. In a rock garden, this diminutive grower is perfect to fill in small, oddly-shaped areas in the shade where other sun-loving plants might struggle for more light.

Lamium, also known as dead nettle, has textured pale green leaves, some with darker green stripes or edges. Flowers range from white ('Nancy') to pale pink ('Pink Pewter') to lavender ('Purple Dragon'), and there are some yellow-flowering varieties as well. The tiny leaves grow on trailing stems that work well to fill in rock garden spaces. This plant flowers fine in the shade, and will spread a bit more slowly in shade than in sun. If the stems get too long and leggy, just cut them back to keep the plants looking neat.

Dianthus is a well-loved cottage garden flower. Also known as pinks, they come in a luscious range of pink hues. Dianthus is part of the carnation family, and many of the cultivars have the signature clove-like scent and full double petals of flower-shop carnations. The spreading varieties have needle-like leaves and fill in rock garden spaces with vibrant foliage and dramatic bursts of color in spring. Try 'Firewitch' (bright pink), 'Greystone' (white flowers, grey-green leaves), 'Bath's Pink' (pale pink heirloom) or a host of two-tone cultivars for a show-stopping look. Deadhead the spent blooms and more buds will form.

Campanula is commonly known as bellflower, and there are many different varieties of different sizes and shapes. The creeping varieties are excellent for rock garden settings, as they grow well from tight crevices and spill beautifully over rocks. Some recommended varieties for rock gardens include Serbian bellflower (Campanula poscharskyana), which has cascading purple flowers and is also known as 'Blue Waterfall,' Carpathian bellflower, with cup-shaped flowers in pale purple or white, and 'Dickson's Gold' which has bright yellow-green leaves and violet-blue star-shaped flowers.

Sedums (also called stonecrop) are wonderful low maintenance, drought-tolerant plants. The creeping varieties of sedum are succulents, perfect for desert gardens or rock gardens with sandy or rocky soil that drains well. There are a number of these low-growing sedum varieties, often grown as ground covers in warm climate gardens. Some have flowers in shades of white, yellow, pink, or red. They spread fairly quickly and are easy to divide and relocate, which can be done at any time throughout the season.