no. 7.401 |
Rock Garden Plants
by J.E. Klett and R.A. Cox 1 (7/05)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 sheets 7.840, Vegetable Garden: Soil Management and Garden Fertilization.
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.
| 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. |
| ‘Atropurpurea’ | 4-6 in. | Shade to part shade | Well drained | Violet-blue | May-June | Bronze-purple foliage. |
| ‘Burgundy Glow’ | 4-6 in. | Shade to part shade | Well drained | Blue | May-June | Pink, white and green foliage. |
| ‘Chocolate Chip’ | 2-4 in. | Shade to part shade | Well drained | Blue | May-June | Wavy, 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. |
| ‘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. |
| ‘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. |
| ‘Blue Clips’ | 6-8 in. | Sun to part shade | Well drained | Blue | June-July | Compact mound of bright-green foliage. |
| ‘White Clips’ | 6-8 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 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 floribundum StarburstTM 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 VerdeTM 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 MountainTM ice plant |
2-4 in. | Sun | Dry, well drained | Pink-purple | June-Sept | Succulent leaves, carpet-like.Plant Select®2002. |
| Dianthus deltoides ‘Brilliant’ Brilliant Maiden Pink |
6-8 in. | Sun topart 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. |
| ’Spotty’ | 6-8 in. | Sun | >Well drained | Rose-red with white spots | May-June | Gray-green grass-like foliage. |
| ‘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. |
| Gazania krebsiana TanagerTM 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. |
| ‘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 LaceTM 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’ |
8-12 in. | Sun | Dry, well drained | Pink | May-June | Mounded habit, silvery foliage. |
| ‘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. |
| ‘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. |
| Oenothera speciosa White evening primrose |
8-12 in. | Sun | Well drained | Pink to white | June-Sept. | Day-flowering. |
| Osteospermum barberiae ‘Compactum’ 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. 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. |
| ‘Mersea Yellow’ | 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. |
| ‘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 serpyllum Mother-of-thyme | 1-4 in. | Sun | Dry, well drained | Purple | June-July | Aromatic foliage; mat-forming. |
| ‘Pink Chintz’ | 1-3 in. | Sun | Dry, well drained | 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 veronica |
1-2 in. | Sun | Dry, well drained | Blue | May-June | Dense mat of small dark green foliage. Plant Select® 1997. |
| Veronica pectinata Woolly veronica | 1-2 in. | Sun | Dry, well drained | Blue to purple | May- July | Gray, mat-like foliage turns purplish in winter. |
| ‘Rubra’ | 1-2 in. | Sun | Dry, well drained | Pink | May-June | Can be evergreen. |
| 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 Fuschsia |
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. |
1J.E. Klett, Colorado State University Extension horticulture specialist and professor, horticulture and landscape architecture; and R.A. Cox, Extension horticulture agent, Jefferson County. 6/00. Revised 7/05.
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