Sidalcea-x-'Party-Girl' (132617 bytes)

Superior Herbacious Perennials for the High Plains

Colorado State University maintains perennial trial gardens at the W. D. Holley Plant Environmental Research Center (PERC) in Fort Collins, Colorado. The main objective of these gardens is to determine which herbacious perennials are best suited for growing in the Rocky Mountain area.

Growth, cultural, and landscape characteristics of these plants have been observed annually, resulting in a database for evaluating their suitability for use in High Plains landscapes

The following are some of the perennials that have shown to be superior performers for the High Plains:

(click on thumbnails for larger pictures)

Astrantia major 'Margery Fish' - Margery Fish Masterwort (79690 bytes) Astrantia major 'Margery Fish' - Margery Fish Masterwort

This particular variety of masterwort reaches its peak bloom in August (shown here in July). With its extra long collar of pink bracts surrounding the petals, it makes a wonderful cut flower for bouquets or drying. Reaching about 2 to 3 feet in height, Margery Fish does best in full sun or part shade and prefers well-drained soils.

DSC08814calamagrostis-x-acu.jpg (142181 bytes) Calamagrostis x acutiflora 'Overdam' - Variegated Feather Reed Grass

This is an erect, clumping cool season grass with variegated medium-green foliage with cream stripes. Variegated Feather Reed Grass grows vertically and makes a natural screen. The flowers are held erect in slender spikes, then tighten into narrow seed heads. This cultivar is non-invasive.

Sidalcea 'Party Girl' - Prairie Mallow or Checker Mallow or False Mallow (106633 bytes) Sidalcea 'Party Girl' - Prairie Mallow or Checker Mallow or False Mallow

This plant is handsome in leaf or in flower. The leaves are shiny and either rounded or palmately lobed. The erect flowering stems reach four feet high and flowers are borne in terminal racemes and resemble miniature hollyhock flowers. 'Party Girl' has silky pink petals and a white central eye.

Lavatera thuringiaca -Tree Mallow (127781 bytes) Lavatera thuringiaca -Tree Mallow

This is a shrubby two to four foot tall plant, closely related to hollyhocks and mallow. The saucer-shaped pink blooms have five showy petals. They are borne in the leaf axils and on loose, terminal racemes. This plant is easy to grow and prefers full sun and well-drained soils.

Miscanthus floridulus 'Giganteus' - Giant Chinese Silver Grass (121570 bytes) Miscanthus floridulus 'Giganteus' - Giant Chinese Silver Grass

This species is certainly the giant of the Miscanthus. It grows 12 to 15 feet high. Excellent as a screen or background plant for smaller grasses. Flower plume develops in mid-September and provides a super winter effect. Stems will persist until spring or later unless cut down.

Acanthus longifolius - Bear's Breeches (128617 bytes) Acanthus longifolius - Bear's Breeches

An unusual, statuesque plant, Bear's Breeches may grow 3 feet by 3 feet. Leaves are deep green and lobed, with deep sinuses. Flower stems appear abouve the leaves and bear purple and white flowers, surrounded by sharp, spiny bracts -  a truly unique bloom. These plants require sun or part shade and should be placed in an area of the garden less prone to drying. Flower buds are less hardy than the leaves and after a particularly cold winter, leaves may appear but no blooms. They are worth the risk!

Coreopsis verticillata -  Threadleaf Coreopsis (123586 bytes) Coreopsis verticillata -  Threadleaf Coreopsis

Threadleaf Coreopsis is covered by golden-yellow daisy-like flowers midsummer. These low maintenance plants perform best in sunny, well-drained sites of low to moderate fertility. Flower are good for cutting and the plant is  drought tolerant.

Heliopsis helianthoides var. scabra 'Incomparabilis' - False Sunflower (127821 bytes) Heliopsis helianthoides var. scabra 'Incomparabilis' - False Sunflower

Its name translates literally as "sun-like" but Heliopsis is smaller, shrubbier and ealier to bloom than true sunflowers. "Scabra" means rough and refers to the sand-papery feel of the stems and leaves. False Sunflower requires full sun and good drainage and will bloom from mid-summer into early fall. It is a great backbone plant for the border and the blooms make excellent cut flowers.

Lysimachia cilata purpurea - Purple Fringed Loosestrife (128986 bytes) Lysimachia cilata purpurea - Purple Fringed Loosestrife

This is definitely one of the more stunning loosestrfes. It has purple foliage offset by bright yellow flowers.

Eupatorium maculatum - Joe-Pye Weed (55521 bytes) Eupatorium maculatum - Joe-Pye Weed

This striking plant has erect, pink-spotted stems and whorl-toothed leaves. The pikish-purple flowers, in late summer, are held in large terminal clusters. The plant matures to 4 to 6 feet in height and 1 to 2 feet wide.

Phlomis russeliana - Sticky Jerusalem Sage (107169 bytes) Phlomis russeliana - Sticky Jerusalem Sage
This member of the mint family has woolly medium-green leaves and square stems with whorls of pale yellow, hooded flowers. Attractive seed heads make this a good winter-interest plant. Sticky Jerusalem Sage prefers full sun and does well in poor soils. It makes an escellent cut or dried flower.
Prunella grandiflora - Large Selfheal (66277 bytes) Prunella grandiflora - Large Selfheal
Large Selfheal is a member of the mint family. It spreads into an excellent ground cover by creeping stems. The purple flowers are two-lipped and held in  whorled spikes and attract bees and other beneficial insects. Prefers full sun to part shade and is not fussy.
Pulmonaria spp. - Bethlehem Sage, Lungwort (20778 bytes) Pulmonaria spp. - Bethlehem Sage, Lungwort
This early spring bloomer is a clump forming perennial known for its' spotted or mottled foliage. The funnel-shaped flowers appear in nodding clusters. Lungwort can tolerate variable habitats including dry shade. There are several cultivars available:
    P. saccharata 'Mrs. Moon': pink buds open to blue flowers that mature to lilac
    P. saccharata 'Roy Davidson': sky blue flowers that fade to pink
    P. officinalis 'Sissinghurst White': pale pink buds open to pure white flowers

Photos: Judy Sedbrook

Information courtesy of Dr. James Klett, principle investigator, and Vale Skiff, Curator, PERC Perennial garden.

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Date last revised: 01/05/2010