no. 7.401

Rock Garden Plants

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.

PlantSelect

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.
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

      '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
Pink-tinged


May-June

April-May


Spreading evergreen foliage; red fruits.
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.

6-12 in.


Sun
Sun to part shade

Sun to part shade


Well drained
Well drained

Well drained


Blue-Lilac
Blue

White


June-July
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
Deep pink


May-June

May-June

May-June


Gray-green grass-like foliage.
Gray-green grass-like foliage.
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
      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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Updated Wednesday, January 08, 2014

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