by J.E. Klett and R.A. Cox * (7/11)
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.
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 smaller, similar rock as 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. Refer to fact sheet 7.235, Choosing a Soil Amendment.
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. Refer to fact sheet 7.231, Xeriscape: Garden Flowers.
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. Refer to fact sheets 7.406, Flowers for Mountain Communities and 7.413, Ground Covers for Mountain Communities.
Plant Select® plants may be viewed online at www.plantselect.org.
2008.
| Table 1: Recommended rock garden plants. | ||||||
| Plant Name | Height | Exposure | Soil Preference |
Flower Color |
Bloom Period |
Remarks |
|---|---|---|---|---|---|---|
| Ajuga reptans Carpet bugle ‘Atropurpurea’ ‘Burgundy Glow’ ‘Chocolate Chip’ |
4-10 in.
4-6 in. 4-6 in. 2-4 in. |
Shade to part shade Shade to part shade Shade to part shade Shade to part shade |
Well drained
Well drained Well drained Well drained |
Blue, purple
Violet-blue Blue Blue |
May-June
May-June May-June May-June |
Spreading ground cover.
Bronze-purple foliage. Pink, white and green 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 ‘Massachusetts’ |
6-8 in. 4-6 in. |
Shade to part sun Shade to part sun |
Acid to neutral,high in humus,well drained Acid to neutral,high in humus,well drained |
White-tinged red |
May-June April-May |
Spreading evergreen foliage; red fruits. |
| Armeria maritima Sea Pink ‘Victor Reiter’ |
4-10 in.
2-4 in. |
Sun
Sun |
Dry, well drained
Dry, well drained |
Pink, white,purple
Pink |
May-June
April-June |
Grass-like foliage; several varieties.
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 ‘Blue Clips’ ‘White Clips’ |
8 in. 6-12 in. |
Sun Sun to part shade |
Well drained Well drained |
Blue-Lilac White |
June-July June-July |
Bright green foliage. Compact mound of bright-green foliage. 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 bloom. |
| 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 dyeri 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’ ’Spotty’ ‘Tiny Rubies’ |
6-8 in. 6-8 in. 4-6 in. |
Sun Sun Sun |
Well drained Well drained Well drained |
Deep pink Rose-red with white spots |
May-June May-June May-June |
Gray-green grass-like foliage. |
| Dianthus plumarius Cottage pink |
6-12 in. | Sun | Well drained | Red, pink, white | May-June | Several varieties. |
| Eriogonum umbellatum Yellow sulfur flower Kannah Creek® |
6-12 in. 6-12 in. |
Sun Sun |
Dry, well drained Dry, well drained |
Yellow Yellow |
May-July May-July |
Umbrella-like flowers; evergreen mounds of foliage turn reddish in fall.
Folliage 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 ‘Biokovo’ Biokovo Cranesbill |
6-12 in. 4-10 in. |
Sun to part shade Sun to part shade |
Well drained Well drained |
Bright pink White-pink |
May-July May-July |
Spreading, mounded form; foliage turns wine red in fall. 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 ‘Wisley Pink’ ‘Wisley Primrose’ |
8-12 in. 8-12 in. |
Sun Sun |
Dry, well drained Dry, well drained |
Pink Yellow |
May-June May-July |
Mounded habit, silvery foliage.
Mounded habit, silvery foliage. |
| Heuchera sanguinea ‘Firefly’ Firefly Coral Bells ‘Snow Angel‘ Snow Angel Coral Bells |
8-18 in. 8-18 in. |
Sun to part shade Part shade |
Dry, well drained Dry, well drained |
Red Pink-red |
May-July May-July |
Green foliage, bell-shaped flowers.
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 ‘Mersea Yellow’ |
6-12 in. 6-12 in. |
Sun Sun |
Dry Dry, well drained |
Orange-red Yellow |
June-Sept June-Sept |
Needle-like evergreen foliage, trumpet-shaped flowers (for both). |
| 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’ ‘Red Carpet’ |
2-4 in. 2-4 in. |
Sun Sun |
Dry, well drained Dry, well drained |
Rose red Rose red |
June-July June-July |
Evergreen foliage with red edge, turns red in fall. 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 Mother-of-thyme |
1-4 in.
1-3 in. |
Sun
Sun |
Dry, well drained
Dry, well drainer |
Purple
Pink |
June-July
May-June |
Aromatic foliage; mat-forming. 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 Zinnia |
4-8 in. | Sun | Dry, well drained | Yellow | June-Sept. | Flowers turn papery and last into winter. |
*J.E. Klett, Colorado State University Extension horticulture specialist and professor, horticulture and landscape architecture; and R.A. Cox, Extension horticulture agent, Arapahoe County. 6/00. Revised 7/11.
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