Rock Garden Plants | Colorado State University Extension Website

Quick facts…

Rock gardens are effective if built on a natural slope or terrace.
Use rocks of one geological type.
Good drainage is necessary.
Plant a variety of species in the rockery.
The garden should not be larger than can be easily maintained.

Introduction

The ideal location for a rock garden is a natural slope or terrace, such as those found at the side or rear of a house based on a split-level or garden-level design.

Use rocks of one geological type. A common rock in Colorado is native granite covered with lichens (moss rock). Rocks are available from nurseries, landscape contractors, and rock dealers. An effective rock garden should have several large rocks, some weighing 200 pounds or more.

Set the rock into the ground so at least one-third is buried. Place rocks in a natural way, following the grain of the rock. Position rocks to control soil erosion between rocks and to allow soil pockets of various sizes for plants. Use a smaller, similar rock to a mulch. Place lichen-covered rock to expose as much of the lichen as possible.

Provide good drainage. Most plants suitable for rock gardens require a well-drained soil. For most plants, incorporate organic matter into heavier clay soils to improve texture and provide better drainage.

A rock garden should be no larger than can be easily maintained. Rock gardens have high maintenance requirements. Weed control is the biggest problem. Most rock garden plants need low to moderate watering amounts and frequency.

Plant a variety of species, repeating some species several times to make the garden look natural. Ideally, rock garden plants should spread slowly. Take care not to overplant.

Plant Selection

Many types of plants are suitable for rock gardens. Generally, plants that are low-growing and have a clumping habit are preferred. Perennial plants are most common in rock gardens, although some annuals can be used. Table 1 lists many rock garden plants, along with their characteristics and cultural requirements. Most plants listed should be hardy to 8000 feet, some higher. 

View Plant Select^® plants online.

Table 1: Recommended rock garden plants.

Plant Name	Height	Exposure	Soil Preference	Flower Color	Bloom Period	Remarks
Ajuga reptans Carpet bugle	4-10 in.	Shade to part shade	Well drained	Blue, purple	May-June	Spreading ground cover.
Ajuga reptans      ‘Atropurpurea’	4-6 in.	Shade to part shade	Well drained	Violet-blue	May-June	Bronze-purple foliage.
Ajuga reptans       ‘Burgundy Glow’	4-6 in.	Shade to part shade	Well drained	Blue	May-June	Pink, white, and green foliage.
Ajuga reptans       ‘Chocolate Chip’	2-4 in.	Shade to part shade	Well drained	Blue	May-June	Wavey,chocolate-brown foliage
Alyssum montanum       Mountain alyssum	4-10 in.	Sun	Dry, rocky	Yellow	April-May	Gray foliage.
Arabis caucasica       ‘Snowcap’       Snowcap       rockcress	6-9 in.	Sun	Well drained	White	April-May	Abundant white flowers over gray foliage.
Arctostaphylos uva-ursi       Kinnikinick	6-8 in.	Shade to part sun	Acid to neutral,high in humus,well drained	White-tinged red	May-June	Spreading evergreen foliage; red fruits.
Arctostaphylos uva-ursi ‘Massachusetts’	4-6 in.	Shade to part sun	Acid to neutral,high in humus, well drained	Pink-tinged	April-May	Spreading evergreen foliage; red fruits.
Armeria maritima       Sea Pink	4-10 in.	Sun	Dry, well drained	Pink, white, purple	May-June	Grass-like foliage; several varieties.
Armeria maritima       ‘Victor Reiter’	2-4 in.	Sun	Dry, well drained	Pink	April-June	Small mounded plant.
Aubrieta deltoidea       ‘Purple Gem’       Purple Gem           Rockcress	4-6 in.	Sun to part shade	Well drained	Purple	April-June	Mounded to spreading shear after bloom.
Aurinia saxatilis       Basket-of-gold	8-12 in.	Sun	Dry, rocky	Yellow	April-May	Grayish-green foliage; shear after bloom.
Campanula carpatica       Carpathian harebell	8 in.	Sun	Well drained	Blue-Lilac	June-July	Bright green foliage.
Campanula carpatica     ‘Blue Clips’	6-12 in.	Sun to part shade	Well drained	Blue	June-July	Compact mound of bright green foliage.
Campanula carpatica      ‘White Clips’	6-12 in.	Sun to part shade	Well drained	White	June-July	Compact mounds of wavy, bright green foliage.
Campanula poscharskyana       Serbian bellflower	6-8 in.	Sun to part shade	Well drained	Blue	June-Aug.	Prolific flowers.
Campanula rotundifolia       Bluebell	8-12 in.	Part shade	Well drained	Blue	May-Sept.	Bell-like flowers on slender stems.
Cerastium tomentosum       Snow-in-summer	4-10 in.	Sun	Dry, well drained	White	May-June	Aggressive; shear after blooming.
Ceratostigma plumbaginoides       Plumbago	8-12 in.	Sun topart shade	Well amended	Blue	Aug.-Sept.	Foliage turns red in fall.
Coreopsis auriculata ‘Nana’ Dwarf Coreopsis	4-8 in.	Sun	Dry and well drained	Orange-Yellow	June-Sept	Dense compact spreading mounds.
Delosperma cooperi       Purple ice plant	2-3 in.	Sun	Well drained	Purple	June-frost	Succulent foliage; to 7000’.
Delosperma cooperi       Red Mountain^® ice plant	1-2 in.	Sun	Dry, well drained	Orange-red	June-Sept	Succulent leaves, carpet-like. Plant Select^®2007.
Delosperma floribundum       Starburst^® ice plant	4-6 in.	Sun	Dry, well drained	Pink with white centers	June-Sept	Succulent leaves, clump form. Plant Select^®1998.
Delosperma nubigenum       Yellow ice plant	2-3 in.	Sun	Well drained	Yellow	May-June	Succulent foliage turns reddish-purple in winter.
Delosperma x ‘Kelaidis’ Mesa Verde^® ice plant	2-4 in.	Sun	Dry, well drained	Salmon pink	June-Sept	Succulent leaves, carpet-like.Plant Select^®2002.
Delosperma x ‘John Proffit’ Table Mountain^® ice plant	2-4 in.	Sun	Dry, well drained	Pink-purple	June-Sept	Succulent leaves, carpet-like. Plant Select^®2002.
Delosperma ‘Pstave’       Lavender Ice™ ice plant	2-4 in.	Sun	Dry, well drained	Pink-lavender	June-Sept	Succulent leaves. Plant Select^®2009
Dianthus deltoides       ‘Brilliant’       Brilliant Maiden       Pink	6-8 in.	Sun to part shade	Well drained	Crimson	May-July	Dark green; carpet-like habit.
Dianthus gratianopolitanus       ‘Firewitch’	6-8 in.	Sun	Well drained	Deep pink	May-June	Gray-green grass-like foliage.
Dianthus gratianopolitanus       ’Spotty’	6-8 in.	Sun	Well drained	Rose-red with white spots	May-June	Gray-green grass-like foliage.
Dianthus gratianopolitanus       ‘Tiny Rubies’	4-6 in.	Sun	Well drained	Deep pink	May-June	Pin cushion growth habit with double flowers.
Dianthus plumarius       Cottage pink	6-12 in.	Sun	Well drained	Red, pink, white	May-June	Several varieties.
Eriogonum umbellatum       Yellow sulfur flower	6-12 in.	Sun	Dry, well drained	Yellow	May-July	Umbrella-like flowers; evergreen mounds of foliage turn reddish in fall.
Eriogonum umbellatum Kannah Creek^®	6-12 in.	Sun	Dry, well drained	Yellow	May-July	Foliage turns red in fall, Plant Select^® 2007.
Gazania krebsiana       Tanager^® Gazania	4-6 in.	Sun	Dry, well drained	Orange	May-Sept.	May need some winter protection. Plant Select^® 2003.
Geranium x cantabrigiense       Cambridge       Cranesbill	6-12 in.	Sun to part shade	Well drained	Bright pink	May-July	Spreading, mounded form; foliage turns wine red in fall.
Geranium x cantabrigiense       ‘Biokovo’       Biokovo Cranesbill	4-10 in.	Sun to part shade	Well drained	White-pink	May-July	Trailing groundcover; foliage turns red in fall.
Geranium cinereum       ‘Ballerina’       Ballerina Grayleaf       Cranesbill	4-8 in.	Sun to part shade	Well drained	Pink-purple	May-Aug.	Deeply divided bright green foliage.
Geranium dalmaticum       Compact Rose       Cranesbill	4-6 in.	Sun to part shade	Well drained	Rose-pink	May-July	Dense spreading foliage turns red in fall.
Geranium magniflorum       LaVeta Lace^®       Cranesbill	6-10 in.	Sun to part shade	Well drained	Purple	May-July	Lacy, dark green foliage turns purplish-red in winter. Plant Select^® 2003.
Gypsophila repens       Creeping baby’s breath	4-8 in.	Sun	Well drained	White or pink	June-July	Mat-like habit.
Helianthemum nummularium       Sunrose	8-12 in.	Sun	Dry, well drained		May-June	Mounded habit, silvery foliage.
Helianthemum nummularium       ‘Wisley Pink’	8-12 in.	Sun	Dry, well drained	Pink	May-July	Mounded habit, silvery foliage.
Helianthemum nummularium       ‘Wisley Primrose’	8-12 in.	Sun	Dry, well drained	Yellow	May-July	Mounded habit, silvery foliage.
Heuchera sanguinea       ‘Firefly’       Firefly Coral Bells	8-18 in.	Sun to part shade	Dry, well drained	Red	May-July	Green foliage, bell-shaped flowers.
Heuchera sanguinea      ‘Snow Angel‘       Snow Angel Coral       Bells	8-18 in.	Part shade	Dry, well drained	Pink-red	May-July	Variegated foliage. Plant Select^® 2003.
Iberis sempervirens       Candytuft	8-12 in.	Sun to part shade	Well drained	White	May-June	Evergreen foliage.
Iris x pumila       Dwarf Iris	8-12 in.	Sun	Dry, well drained	Blue or yellow	May-June	Short, stiff clump-forming leaves, several varieties.
Linum flavum       ‘Compactum’  Dwarf       golden flax	10-15 in.	Sun	Well drained	Yellow	May-July	Dark green foliage.
Nepeta x ‘Psfike’       Little Trudy^®       catmint	8-12 in.	Sun	Well drained	Lavender	June-Sept	Low, spreading growth habit. Plant Select^®
Oenothera speciosa       White evening       primrose	8-12 in.	Sun	Well drained	Pink to white	June-Sept.	Day-flowering.
Osteospermum barberiae       Purple Mountain^®      Sun Daisy	8-12 in.	Sun to part shade	Well drained	Purple	April-August	Evergreen clumps of foliage. Plant Select^® 1998.
Osteospermum spp.       ‘Avalanche’^PPAF       sun daisy	8-12 in.	Sun	Well drained	White to lavender	April-August	Evergreen clumps of foliage. Plant Select^® 1998.
Osteospermum spp.       Lavender Mist^®       Sun Daisy	8-12 in.	Sun to part shade	Well drained	White to lavender	April-August	Evergreen clumps of foliage. Plant Select^® 1998.
Penstemon caespitosus       Creeping       penstemon	3-6 in.	Sun	Well drained	Blue	May-June	Mat-like; dark green foliage.
Penstemon pinifolius     Pineleaf penstemon	6-12 in.	Sun	Dry	Orange-red	June-Sept	Needle-like evergreen foliage, trumpet-shaped flowers.
Penstemon pinifolius     ‘Mersea Yellow’	6-12 in.	Sun	Dry, well drained	Yellow	June-Sept	Needle-like evergreen foliage, trumpet-shaped flowers.
Phlox subulata       Moss pink or       creeping phlox	4-6 in.	Sun	Well drained	Pink, white, lavender	April-May	Several varieties based on flower color; may winterburn.
Potentilla nepalensis       ‘Miss Wilmott’       Miss Wilmott       cinquefoil	8-12 in.	Sun	Well drained	Pink to red	May-July	Strawberry-like leaves on clump plants.
Prunella laciniata       Lacy Self Heal	8-12 in.	Sun to part shade	Moist	Pink	May-June	Dark green fuzzy leaves, mat-forming.
Pulsatilla vulgaris       Pasque Flower	6-12 in.	Sun to part shade	Well drained	Blue to purple, red, white	March-April	Silky leaves appear after flowering, followed by long-lasting feathery seedheads.
Saponaria ocymoides         Rock soapwort	6-10 in.	Sun	Well drained	Pink	May-July	Shear after bloom; evergreen mat-like foliage.
Saxifraga oppositifolia       ‘Purple Robe’       Purple Robe       saxifrage	6-10 in.	Sun to part shade	Well drained	Purple	June-Sept	Bright green mounds, cup-shaped flowers.
Sedum spp .         Stonecrop	Variable 1-15 in.	Sun	Any, well drained	Varies with species	July-Oct.	Some evergreen; some more appropriate as ground covers.
Sedum acre         Gold Moss       stonecrop	2-4 in.	Sun	Dry, well drained	Yellow	May-June	Evergreen leaves, fast spreading, star-shaped flowers.
Sedum spurium         ‘Dragon’s Blood’	2-4 in.	Sun	Dry, well drained	Rose red	June-July	Evergreen foliage with red edge, turns red in fall.
Sedum spurium         ‘Red Carpet’	2-4 in.	Sun	Dry, well drained	Rose red	June-July	Red, wedge-shaped evergreen foliage.
Sempervivum spp.         Houseleek       Hen and chicks	1-6 in., flower taller	Sun	Dry, gravelly	Pink to red	July-Sept	Succulent, evergreen foliage in rosettes.
Stachys byzantina       ‘Silver Carpet’       Silver Carpet       Lamb’s Ear	6-12 in.	Sun	Infertile, well drained	Not important	Not important	Rarely flowers; velvety silver foliage.
Teucrium chamaedrys       Germander	6-12 in.	Sun	Well drained	Purple-pink	July-Aug.	Evergreen; cut back after flowering.
Thymus x citriodorus         Lemon thyme	4-12 in.	Sun	Dry, well drained	Pink	June-July	Lemon-scented foliage.
Thymus praecox ‘Pseudolanuginosus’     Woolly thyme	1-3 in.	Sun	Dry, well drained	Infrequent, pink, and purple	June-July	Woolly-gray foliage turns purplish in winter.
Thymus praecox   articus	1-4 in.	Sun	Dry, well drained	Purple	June-July	Aromatic foliage; mat-forming.
Thymus praecox   Mother-of-thyme	1-3 in.	Sun	Dry, well drainer	Pink	May-June	Pink flowers over mat-like foliage.
Verbena bipinnatifida       Valley Lavender^®       verbena	3-6 in.	Sun	Dry, well drained	Purple	June-Aug.	Trailing stems with deeply cut leaves. Plant Select^® 2005.
Veronica liwanensis         Turkish speedwell	1-2 in.	Sun	Dry, well drained	Blue	May-June	Dense mat of small dark green foliage. Plant Select^® 1997.
Veronica pectinata       Woolly speedwell	1-2 in.	Sun	Dry, well drained	Blue to purple	May- July	Gray, mat-like foliage turns purplish in winter.
Veronica prostrata       Prostrate       speedwell	2-6 in.	Sun to part shade	Well drained	Blue	May-June	Dense mats, dark green foliage.
Veronica repens      Creeping       speedwell	1-3 in.	part shade	Well drained	Blue	May-June	Mat-like habit.
Veronica x hybrida      Crystal River^®       speedwell	1-3 in.	Sun to part shade	Well drained	Blue	May-June	Evergreen, small rounded leaves. Plant Select^® 2003.
Viola cornuta       Horned violet	4-10 in.	Sun to part shade	Moist	Purple	April-July	Tufts of dark green foliage.
Viola corsica       Corsican violet	6-8 in.	Sun to part shade	Moist	Purple	April-Sept	Tufts of dark green foliage. Plant Select^® 2003.
Zauschneria garrettii       ‘Orange Carpet’       Orange Carpet^®       California       Fuchsia	4-10 in.	Sun	Dry, well drained	Reddish-orange	Aug.-Sept.	Mounded growth habit with trumpet-shaped flowers. Plant Select^® 2001.
Zinnia grandiflora       Rocky Mountain	4-8 in.	Sun	Dry, well drained	Yellow	June-Sept.	Flowers turn papery and last into winter.
Zinnia grandiflora       Zinnia	4-8 in.	Sun	Dry, well drained	Yellow	June-Sept.	Flowers turn papery and last into winter.

Reference: CSU Fact Sheet 7.401