There has been a lot of interest at our nursery, and in current plant-breeding programs for smaller shrubs. Most of the old-time favorite shrubs are very large. Most lilacs, viburnums, honeysuckles, forsythias, privets, elderberries, serviceberries, butterfly bushes and hibiscus are 6’-12’ high and often as wide. These are great to provide screening and big masses of color along fences or the back of the border.
But many people these days are not gardening on half-acre lots; or they have been avid gardeners for 10-20 years and have little space left, or they are looking for low maintenance accents that fit into small spaces or mix with perennials. In addition, we garden in Colorado conditions where sweet little things fresh out of east or west coast breeding programs crash in our low humidity, fierce sun, strong wind, shocking temperature changes and alkaline soils.
Yes, we have potentillas and some dwarf spireas, but what other rugged shrubs under three feet high and wide are successful here?
Genista lydia, Dyer’s Greenwood, is a small broom 12”-18” high and 2’-3’ wide. Evergreen arching branches form a compact mound. The leaves are small and the bight yellow, pea-like flowers smother the plant in early summer. This is a tough plant that does well in full sun and low water conditions. It is tolerant of various soil types and seems more cold-tolerant (zone 4) than many Cytisus brooms. Do not over-water or prune back hard. Genista lydia is elegant and fits in both formal and informal gardens.
Clematis fruticosa ‘Mongolian Gold’ is a non-vining shrub 2’ high and 3’ wide. It blooms for two months in summer with pendant, yellow, fragrant bells, followed by attractive smokey seedheads. This bush clematis likes sun and shades its own roots. It is tough, but does not like either bone-dry or soggy soil. The shiny, dark green leaves make a nice effect themselves. My wife, Eve, has been growing this clematis for 10 years and says, “It has never had a bad year.” It was collected originally in Mongolia, and was chosen as a Great Plants for the Great Plains selection. It is hardy to zone 4.
Amorpha nana is a Colorado native shrub that grows 2’-3’ high and wide. It is distinguished from its better-known cousin, Amorpha canescens, by being green leaved and slightly shorter. Commonly known as Dwarf Lead Plant, it has been called “Dwarf Dead Plant” in spring, since it is so late to leaf out that it is never caught by late spring frosts. The summer-blooming spikes of tiny fragrant purple flowers are both a welcome sight for human eyes and an attraction to many kinds of bees and butterflies. The roots host nitrogen-fixing bacteria. Dwarf False Indigo is another common name for this very drought tolerant native. Prune off dead flower spikes and remove any dead wood in spring when the leaves start to show. It needs little else.
‘Mini Man’ Viburnum is a dwarf Manchurian Viburnam (V. burejacticum), found by propagator Scott Skogerboe at Ft.Collins Wholesales nursery. Typically, the Manchurian Viburnum grows 7’-8’ tall and wide, but this form only grows 3’ for me in dry shade, but could attain 5’ if watered generously. It is very compact, with thick, velvety gray-green foliage that turns burgundy in fall. The blossoms are clusters of small, creamy white flowers that are followed by red fruits that mature to black. It is quite drought tolerant, hardy to zone 3 and is a beautiful small specimen for part shade.
Leptodermis oblonga (False Lilac) is a little known, dwarf, dense mounding shrub from the Himalyayas, gradually reaching 12”-24” high and wide. The pointed mid-green leaves are small and simple. Leptodermis is late to “wake up” in the spring, but be patient; it will produce small, very pretty clusters of violet-pink, tubular blooms in late spring, and again in fall. The flowers attract bees, butterflies and hummingbird. It is rarely troubled by diseases, insects or deer. Leptodermis grows in most well-drained soils in full to part sun with moderate watering. It has been alive in our garden for six years. It is hardy to zone 5 and did die back last winter but is already blooming.
Arctostaphylos x coloradoensis ‘Cascade’ is a manzanita with bright green, evergreen leaves and tiny white flowers blushed with pink, followed by red berries in fall. It is more compact than many hardy manzanitas, growing 1’-2’ high and 3’-4’ wide. This selection was made by Boulder plant explorer, Alan Taylor. ‘Cascade’ has cinnamon-red to purplish exfoliating bark and, as its name implies, cascades over rocks and banks. It is even successful under evergreen trees. Most manzanitas seem to need moderate moisture the first year or two and then they are fairly drought tolerant.
Daphne susannae ‘Lawrence Crocker’ is a beautiful, small evergreen shrub, 8”-12” high and 12”-18” wide. Its deep pink flowers are very fragrant and cover the plant in late spring, then bloom off and on through the season. Daphne likes our alkaline soil, and ‘Lawrence Crocker’ is happy in part shade or sun as long as it is watered moderately and is protected from winter sun and strong winds. It needs soil with good drainage so maybe add some expanded shale to your dense clay. My wife, Eve, has 3 specimens that all survived last winter. She loves the fragrance, which is worth getting on your hands and knees for the intoxication.
‘Pawnee Buttes” Sand Cherry is a short form of Prunus besseyi, our native Sand Cherry. It blooms in early spring with fragrant white flowers that are very attractive to bees and other pollinators. The shiny green leaves turn red to purple in the fall. Like the taller form, ‘Pawnee Buttes’ produces round, black fruits in the summer that are eaten by birds, but are usually too bitter for humans. Although it only grows to about 16” in height, it can spread up to 4’-5’ wide. Summer pruning of the longer stems and growing in drier conditions can keep this water-wise shrub more compact. It was chosen by Plant Select in 2000.
Other small native shrubs include: Dwarf Rabbitbrush, Snakeweed (Gutierrezia sarothae), Ceanothus fendleri, Purshia tridentata and Holodiscus dumosus. Non-native small shrubs include Paxistima canbyi, Mahonia aquifolium compactum, ‘Kelsey’ Dogwood, ‘Little Devil’ Ninebark, Thuja ‘Hetzi Midget’, ‘Crimson Pygmy’ Barberry. ‘Prairie Petite’ Lilac and Caragana frutex globosa, and of course many dwarf spireas and potentillas.
Many worthy small shrubs did not make this list: those that are short, but wide spreading, roses, and currants and gooseberries that are mostly 4’ x4’ but have ornamental berries or flowers.
Pruning is good to help keep shrubs in their place. And the word is out from California that you get the greatest dwarfing effect by pruning around the Summer Solstice, June 21.