Xeriscape Groundcovers Display and Test Beds
This half of the test area uses half the water of bluegrass
Erigeron glaucus ‘Olga’
Dianthus petraeus noeanus
Iberis, dwarf varieties
Aubrieta d. ‘Purple Gem’
Eriogonum umb. ‘Kannah Creek’
Dianthus grat. ‘Painted Lady’
Satureja mont. ssp. Illyrica
Phlox sub. ‘Boothman’s Variety’
Linum dolmiticum hybrid
Lamiastrum ‘Herman’s Pride’
Geranium cant. ‘Biokovo’
Geranium ‘Dwarf Purple’
Delosperma ‘John Proffitt’
Saponaria ‘Max Frei’
Origanum vulg. ‘Humile’
Potentilla neumanniana Nana
This half of the test area uses a quarter the water of bluegrass
Penstemon pinifolius ‘Mersea Yellow’
Teucrium cham. compactum
Tanacetum densum var. amani
Dianthus grat. ‘Tiny Rubies’
Marrubium rotundifolium (silver edge)
Thymus ‘Back Wall’
Thymus ‘Red Creeping’
Clear Gold Thyme
Goldstream Lemon Thyme
Sedum ‘Bronze Carpet’
Sedum ‘ Dragon’s Blood’
The groundcovers in this half of the demonstration area use half as much water as bluegrass or less
1. Erigeron glaucus ‘Olga’ is a dense, dark green rosette, 3” – 4” high and 5”-10” diameter. The flowers, on stalks to 6”-12” tall are 11/2” daisies with pale lavender rays and yellow centers, blooming June to November. Filled in quickly and looked good all year.
2. Erigeron scopalinus (Rock Daisy) is a 1”-2” mat-forming rock garden plant, 8”-12” in diameter with tiny green leaves and sparkling white, daisy flowers just above the foliage. It is native to the mountains of Arizona.
3. Delosperma ‘Kelaides’ was planted in the spring of 2002. It is reported to be a dwarf sport of the hardy iceplant D. cooperi with iridescent, salmon-pink flowers, vigorous, compact and floriferous, to 2” tall. It held up well in the heat of 2002; its drought tolerance is yet unknown.
4. Sempervivum arachnoides and other ‘Cobweb Hen & Chicks’ look good in all seasons, but are filling in very slowly. They make tight clusters of rosettes covered with white “webbing”, ½ – 3” tall, evergreen, eventually filling in densely, crowding out weeds. The rosy red-pink star-like flowers are held on leafed stalks several inches above the rosettes, and the rosette that blooms will die after flowering.
5. Herniaria glabra (Rupturewort) has rich, dark green foliage 1” tall. Filled in a 2’ x 3’ space very quickly. It is evergreen, with insignificant, tiny flowers. Makes an excellent groundcover for dwarf bulbs and could be used between stepping-stones, or to edge a walk. It looks good 12 months of the year.
6. Aethionema grandiflora, a species of Lebanon Stonecress, is an 8”–10” tall sub-shrub, spreading to 10”-12” wide, with very blue foliage. In May, the ends of the branches burst into bloom with small, fragrant pink flowers that smother the plant, continuing into June. Loves sun and seems to thrive on drought. Aethionema grandiflora is very beautiful, evergreen, and has proved successful in many Boulder-area gardens. It is not a true groundcover.
7. Dianthus petraeus noeanus (Jasmine Dianthus) forms compact cushions of narrow leaves to 12” in diameter. In midsummer, flowering stems elongate to 9” high, each with a finely cut white flower producing a delicious and powerful perfume. A single flower makes a worthy gift. It is long-lived and drought-tolerant. Shear after flowering.
8. Scutellaria supina makes 3”-6” high mounds of ½” matte green leaves that are deeply viened and attractively notched. The mounds spread to 16”-18” wide. It blooms generously over a long period in spring on stalks to 10”, the hooded flowers being cream or pale yellow, often with light purple hoods or markings, and will rebloom if deadheaded. It likes full sun for at least ½ day, and is moderately drought tolerant. It was just planted in our display bed in spring of 2002.
9. Iberis (Evergreen Candytuft) dwarf varieties: here we are testing Iberis sayana – 4” x 12”, Iberis saxatilis – 3”-6” high mounds spreading to 12”-18”, and Iberis taurica. All are evergreen perennials for sun or part-shade, with narrow, rich, dark green foliage, covered with white flowers in spring. They make dense mounds and are mostly very drought-tolerant.
10. Campanula garganica is one of few bellflowers that has survived in my xeriscape garden. It makes a mat 4”-6” high and 12”-18” in diameter of densely grown greyish leaves. The flowers are violet-blue and star-shaped, often with a small white eye, blooming in June/July. It is not really a xeric plant, but tolerates low-watering, especially in part shade. A beauty, and tight enough to exclude most weeds.
11. Aubrieta deltoidea ‘Purple Gem’ (Purple Rock Cress) is a dense gray-green mat 4”-6” high and 8”-12” wide, blooming with small four-petaled purple flowers in early spring. It is evergreen and quite drought tolerant. Shear off flowers after blooming. It is a dependable performer, tolerant of many soils and conditions. It was fast to fill in.
12. Globularia cordifolia has tiny dark green leaves which form dense woody, evergreen mats 1”-3” tall. These grow slowly and are not generally used as a groundcover, however for small areas and around flagstones and around stones in general, this Globe Daisy can be superb. It flowers with ½” round blue, ball-like flowers on short stems. While not tolerant of extreme drought, it likes sun and alkaline soil and will do well with little watering if given protection from winter sun.
13. Eriogonum umbellatum ‘Kannah Creek’ is a fine variation on the mountain native Sulphur Flower. This xeric perennial has evergreen mounds of leathery oval leaves 4”-8” high and 16”-20” wide, with sulphur yellow flowers in umbels on 10” stalks. ‘Kannah Creek’, however, has mahogany fall, winter and early spring color and the yellow flowers start out brownish, giving a two-tone effect. It was fast to fill in and has a long blooming period, with the dried flowers continuing to be attractive. Hard to find, but worth it.
14. Acaena myriophylla is a little-known groundcover spreading with great vigor. The foliage is tight, beautiful and ferny. The flowers are insignificant, and the seed is a non-prickly bur. In the spring the old runners from the previous season were brown and were a little troublesome to prune out. Perhaps it could be mowed. It could be a great lawn replacement or possibly is too aggressive, possibly invasive. We will watch and test it.
15. Dianthus grat. ‘Painted Lady’ seedling is one form of a highly variable plant which has very fragrant white flowers splotched with maroon. The foliage is a low blue-gray grassy mat 4”-5” high and 10” in diameter. It filled in quickly, but seemed to perform better with a little water the first year. Now it looks excellent.
16. Satureja montana ssp. illyrica is a compact winter savory with leathery leaves and woody stems. The flowers are blue to violet over a long period in the fall. It grows 4”-6’ high and 12”-15” in diameter. The foliage is very attractive and the plant is tough, needing little water. It grows to 9000’.
17. Phlox subulata ‘Boothman’s Variety’ is a fast spreading Moss Phlox 3”x18”-24” wide. The flowers are a vivid lavender blue with a dark purple eye. This variety has held up better in heat and sun than others, though it also does well in part shade. The leaves are needle-like and evergreen. Moss Phlox does well covering large areas. The foliage looked dry this spring, but it recovered quickly and bloomed well, and again in fall.
18. Linum dolmiticum hybrid (Yellow flax) is a small woody yellow flax 6”-9” tall in flower, 6” in diameter. It holds a compact form with attractive foliage and rich yellow flowers. It is very long blooming.
19. Waldsteinia ternata (Barren Strawberry) has attractive strawberry- like leaves and the 6”x12” plants grow together to form a mat. The flowers bloom in early spring a deep yellow. It tolerates dry shade very well, but was somewhat burned this spring. It recovered quickly once irrigation was turned on.
20. Lamiastrum gal. ‘Herman’s Pride’ (Yellow Archangel) has 8”-12” vertical square stems with nettle-like leaves, pointed and coarsely toothed, with beautiful silver markings. In June/July it flowers with yellow, lipped flowers. It can tolerate sun or shade. Perhaps it is best used in dry shade. It filled in the test bed quickly and looks good most of the year.
21. Geranium cinereum ‘Ballerina’ is a durable hardy geranium growing 4”-6” high and 14” in diameter. The leaves are lobed and evergreen and turn red in the fall. The striking flowers are silvery-pink with reddish purple veins and held above the foliage. It is quite tolerant of drought, especially in part shade. It is very long blooming.
22. Geranium cant. ‘Biokovo’ has evergreen, lobed leaves that are fragrant when rubbed, which turn red in the fall. The plants grow densely inhibiting weeds and spread rapidly 8” high and 16”+ wide. The flowers are a pale pink and bloom for a long time. The species Geranium cantabrigiense is very similar with darker pink flowers. Both are tolerant of different soils, sun or shade and do well dry.
23. Geranium dalmaticum is an evergreen hardy geranium that makes a dense mound 6”x12” of fragrant foliage that turns red or orange in the fall. The flowers are 1” wide of a clear pink and are long blooming. It grows in sun or shade, but looks better in part shade if very dry.
24. Geranium sanguineum ‘Dwarf Purple’ has healthy lobed foliage that turns red in the fall, growing 4”-6” high and 12” in diameter. The flowers are a purple pink. It has been slow to fill in. The G. sanguineum varieties in general are very drought tolerant.
25. Delosperma ‘John Proffitt’ (Table Mountain Ice Plant) has wedge-shaped foliage which is very dense, fast-spreading, and is turgid and is tinged purple in winter. It grows 2”-3” high and 16”-24” wide. The very long blooming flowers are a purple red with a creamy eye. It is reported to be more cold hardy than D. cooperi. It has performed very well so far.
26. Scabiosa lucida is a dwarf pincushion flower 4”-8” high and 12” in diameter. It is not really a groundcover but mounds densely to cover the ground and suppress weeds. The small rosy-lilac flowers are on short stems and bloom for a long, long time even under low water conditions as it has a big tap root. It can self sow in moist soil.
27. Gazania linearis is a South African daisy with long strap-shaped leaves, making a dense mound 6”-8” x 16”. It has shiny, golden yellow daisy flowers with patterned centers that bloom for months. The fluffy seed self sows and along with the stems, need spring cleanup. It filled in quickly.
28. Alyssum wulfenianum (Low Basket of Gold) is a gray-leafed mat that is quite prostrate. It has gold flowers in spring and again in simmer. It is not as floppy as common Basket of Gold, but can self sow. Probably a good meadow plant.
29. Prunella grandiflora (Self Heal) is usually grown as a part-shade plant, and has done better than expected in full sun with little water. It filled in quickly and densely 5”-6” high and 18” wide, shooting up to 12” when it flowers. The showy dark violet-purple flowers are lipped and hooded and bloom in clusters in June and July, sometimes longer. It is excellent in dry shade, good for suppressing weeds, and is possibly too aggressive under moist conditions.
30. Saponaria ‘Max Frei’ (Max Frei Soapwort) is a late blooming soapwort with large pink flowers in dense clusters. It has a very long flowering period in summer and fall. Although very showy, it is more compact to 6” high and only 18” wide. It is drought tolerant.
31. Cerastium candidissimum is a low-growing Snow in Summer that has dense, very silvery foliage 1”-2” high and 8”-12” wide. It has beautiful white flowers in spring. It is slow to establish and needs some water for the first year. In the second year it is looking beautiful even in winter. It doesn’t flop like C. tomentosa, but it is best to dead-head.
32. Origanum vulgare ‘Humile’ is a dwarf, spreading oregano, growing up to 12” tall in flower and spreading 16” wide. It made healthy green mounds that filled in quickly, and the leaves have a good culinary flavor. The purplish flowers bloom in the fall. It is a good drought tolerant groundcover for the herb garden or in front of taller perennials.
33. Veronica cuneifolium is a very dense creeping veronica that filled in quickly. The foliage is beautiful, gray-green, toothed and evergreen to 3” high by 12” wide. The flowers are a good blue with white markings, blooming in spring. It is perhaps not the most drought tolerant creeping veronica, but it held up well in 2002.
34. Potentilla neumanniana ‘Nana’ is a dwarf cinquefoil without runners, making a mound 3”-4” high and 12” in diameter. The flowers are a golden yellow and bloom spring into summer. It looked stressed this spring, but perked up with a little irrigation. For eight years a specimen starred in my xeriscape garden.
35. Dianthus gratianopolitanus is a rugged Cheddar Pink from Europe. It filled in rapidly, making a dense, evergreen mound 6”-8” high and 12” in diameter, extending to 12” in flower. It blooms in June/July with single pink, very fragrant flowers. Our strong winter sun may burn it, but it still may prove successful. Shear after flowering.
The groundcovers in this half of the demonstration bed use only one fourth as much water as bluegrass
36. Achillea serbica is mat-forming Serbian Yarrow. It has beautiful, silvery gray, evergreen foliage 6” high and 12”-16” in diameter that filled in quickly. In May/June it blooms with pure white daisy like flowers with a yellowish eye. It is quite xeric, but can burn our in extreme conditions. It is best to shear after flowering. It is almost identical to Achillea ageratifolia.
37. Penstemon pinifolius ‘Mersea Yellow’ is a yellow-flowered form of the Pineleaf Penstemon. It is 4” tall in spring and 10”-15” high in bloom. It is beautifully evergreen through winter making 12” diameter mounds. The leaves are pineneedle-like, and the flowers are narrow and tubular and bloom profusely over a long period.It filled in quickly.
38. Achillea kellereri (Keller’s Yarrow) is one of the best and most elegant yarrows for a xeriscape. It has beautiful, silvery-blue cut-leaf foliage that is compact, 8” x 12”-16” wide that doesn’t spread by rhizomes. The flowers are a lovely white, blooming throughout the summer. Good in full sun or part shade, drought and rabbit tolerant.
39. Pterocephalus depressus is a wonderful mat-forming perennial with 2” high textured gray foliage growing 12”-18” in diameter. The flowers are low, pink scabiosa-like and are followed by silvery-pink, fluffy seed heads. It is drought tolerant and long lived in sun or part shade.
40. Teucrium chamaedrys compactum is a dwarf germander growing 5”-8” high and 8”-10”wide. The foliage is glossy, scalloped, dense and weed-smothering. The flowers are rosy purple, blooming in summer. It tolerates dry and infertile conditions. We are still testing this compact variety; the non-compact form is industrial tough.
41. Marrubium rotundifolium has felty, round, gray-green leaves. It grows to 6”-10”high and 15”-20” in diameter, and looks mostly evergreen in winter. The flowers are not showy and some people prefer to shear them to keep the foliage cleaner. It does well in dry, well-drained conditions.
42. Tanacetum densum var. amani is called Partridge Feather because of the truly feather-like shape of its leaves which are a definite silver color. It is 6”-8” high and can get 4’ in diameter with age; it quickly filled in the 3’x3’ space. It did, however, rot out in a 12” area, which was replanted. The yellow button flowers bloom in summer and some people shear these to keep the foliage stronger. It is very xeric.
43. Veronica pectinata is a very fast growing creeping veronica that is evergreen, 3”-4” high and up to 4’ in diameter after several years. The violet-blue flowers with a white eye bloom very early in the spring and again a little in the fall. Spots can rot with too much water or burn out with too little, and still it is a valuable groundcover. Shear flowers after blooming and rub out brown areas with a gloved hand to regrow and fill in.
44. Dianthus grat. ‘Tiny Rubies’ makes a dense low 2”-3” mat of evergreen, blue-gray foliage which can spread 12”-18” wide. The flowers are on short stems, rich pink and double. They were quick to fill in. They showed some drought stress, but recovered and bloomed well.
45. Marrubium rotundifolium (silver edge) is a showy form having its gray-green leaves with a cream edge. It grows to 4”-6” high and 12” in diameter and is mostly evergreen. The flowers are uneventful and can be sheared off to keep the foliage denser and neater. It is drought tolerant.
46. Reiter Thyme is a wide-spreading creeping thyme, 3” high and 30” wide. It is thick-growing, weed-smothering, low water, and step-able with lavender flowers in mid summer. It is recommended as a thyme lawn.
47. Anacyclus depressus (Atlas Daisy) is an evergreen mat of grayish lacy foliage 3” high. The flowering runners are prostrate, up to 12” long, and produce attractive 1” white daisy flowers with yellow centers. The undersides of the petals are red which shows when the flowers close on cloudy days. It is extremely drought tolerant and filled in quickly. It may be necessary to cut off the “runners” after flowering. It can be somewhat short lived, but self sows. It is tap-rooted and industrial tough.
48. Thymus languinosus is a creeping thyme that is only two years old and new to the trade so we don’t know it yet. It closely resembles woolly thyme, with its gray furry foliage ½” high and spreading to 12”-18” at least. It is supposed to flower and be less prone to rotting out in the center than woolly thyme. So far it looks great.
49. Thymus ‘Back Wall’ is a very tight creeping thyme, only ¼” high. It is slow-growing and so far seems less prone to burning out in spots than Thymus Minus which it resembles. It is excellent between flagstones and for covering small areas in sun.
50. Dianthus freynii is a very tight, blue mat 2”-4” high and 8”-16” wide. In flower it gets 5”-6” high in June, being smothered in fragrant soft lavender pink flowers on 1” stems. Shear after flowering. The foliage is evergreen and the plant does well in alkaline soil, sun and very dry soil.
51. Dianthus simulans is somewhat surprising in that its 10” diameter mounds are nearly perfect low hemispheres 4”-5” high. They are very tight and evergreen and can burn in winter sun, though they usually fill back in rapidly in spring. There can be sparse very small pink flowers. It is very drought tolerant. You may pet it.
52. Veronica liwanensis (Turkish Veronica) is 1”-2” high evergreen mat to 24” in diameter with small glossy, dark green leaves. In spring it blooms, covering the foliage with cobalt blue flowers. It is good to shear all the veronicas after blooming. It tolerates some shade and is very xeric. It was a Plant Select winner in 1997.
53. Veronica oltensis, Thyme-leaf Veronica is very low ½”-1” and 24” wide. It is evergreen and xeric, with tiny oak shaped leaves. The spring flowers are an azure, sky blue, tucked into the foliage. It can be used between flagstones or it will spread widely as a real groundcover.
54. Veronica allioni (the real V. allioni) is a wonderful compact speedwell 4”-8” high and 12”-15” wide. In spring the foliage is a low mat of dark green leaves that extend in late spring to 8” spikes of dark blue flowers. A good xeriscape plant for the front of the border, along walks or between rocks in a rock garden.
55. Veronica tauricola is another creeping veronica with beautiful silvery gray leaves, making a mat 2” high and 12”+ in diameter. It quickly filled in the bed. In spring the blue flowers are outstanding against the silvery foliage. It is new to commerce and we need to test it further, but it looks very promising.
56. Thymus baeticus is a very strong growing, evergreen creeping thyme 3”-5” high and 24” wide. The lavender pink flower clusters are larger than most thymes and showy. It quickly filled in except where one died. In general it is very healthy and promising. Shear after flowering.
57. Thymus serphyllum ‘coccineum’ (Red Creeping Thyme) is 1”-2” tall and 18” wide, and blooms rose-red in June/July. It filled in quickly and is evergreen and drought tolerant. It has performed very well and seems very durable. Very showy in flower.
58. Pink Chintz Thyme is only 2”-3” high and 18” wide. It is very dense and attractive with profuse salmon-pink flowers in spring. The foliage is evergreen and holds up well with winter sun and dry conditions. Shear after flowering.
59. Clear Gold Thyme mounds 2”-4” high and 12”-16” in diameter with good gold-tinged foliage. It is evergreen and looked very attractive last year. In the spring, however, it looked burned, but now has recovered very well. We will test it further.
60. Tuffet Thyme is 2”-4” tall and spreads quickly. In the summer it blooms with rose pink flowers, and the foliage is bright green. Last year after flowering, half of it died out, perhaps because it was cut back too hard. Otherwise it looks very healthy and successful.
61. Goldstream Lemon Thyme is a low-growing, creeping thyme only 1”-2” high. The gold markings are most pronounced in spring. The flowers are mauve. It is good between stepping stones, along walks and by benches where the lemon fragrance will be aroused by foot traffic.
62. Thymus neiceffii is called Juniper Thyme because the 2” high foliage looks somewhat like a tiny groundcover juniper. The foliage is evergreen and very attractive. The flowers bloom very early in spring with bright rose-pink blossoms that cover the foliage. It spreads 12”-15” and looks very promising.
63. Woolly Thyme is a low groundcover ½”-3” high and spreads up to 18”-24” in diameter. It is evergreen and works well between flagstones or planted in a large area. It can die out in patches, but generally is very successful. It filled in quickly and rarely flowers.
64. Thymus minus is a very tight, low thyme ½”-3” high and 18” wide. It is very slow-growing but excellent between flagstones. In summer small pink flowers bloom close to the evergreen foliage. It does burn in winter sun, so some protection or supplemental water may be helpful.
65. Sedum spurium ‘Bronze Carpet’ is an evergreen goundcover growing 2”-3” high and 24”+ wide. The stems creep along the ground, rooting as they go. The foliage is a good bronze color most of the season. The flowers bloom in summer with a purplish-pink color. It spreads quickly and is very durable.
66. Sedum spurium ‘Dragon’s Blood’ is the same as Bronze Carpet except the leaves are green with reddish edges, which turn red in the fall. It is a big spreader, but this aggressive behavior might make it very suitable as a lawn substitute. If it is grown with too much moisture it is loose and weeds become a problem. Give it sun and dry.
67. Sedum hybridum is an evergreen succulent 3” high and creeps 12”-18” or wider. The flowers bloom yellow in summer and sometimes again in fall. In late fall, the foliage can turn a dark red. It was planted in the spring of 2002.
68. Sedum album (White Moss Sedum) is an extremely drought tolerant and wide spreading succulent. Any pieces that break off its rich evergreen foliage will root. However it is not hard to dig out if undesired. The white flowers are refreshing as they bloom in the heat of summer. Dead-heading must be done by shearing, not pulling.
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