I’m thinking of planting broom. Yes, one of those small, shrubs with the yellow pea-like flowers. Before you shudder and call me crazy, realize that invasive Scotch Broom (Cytisus scoparius, right) isn’t the only broom in cultivation, and the characteristics that led gardeners to import brooms in the first place are shared by many other species, some of which are hardy enough to survive drought, hot sun, and cold winters.
Lydian Broom, also known as Woadwaxen (Genista lydia), is one species that thrives in Colorado, but doesn’t make a pest of itself. A compact, deciduous shrub, this broom only reaches one to two feet both high and wide, but makes a huge impact in late spring and early summer when it’s totally covered with flowers of an intense, road-sign yellow. Small, bright green leaves are attractive even after the flowers fade. The branches tend to arch, and some will trail over a wall or down a slope, adding to the plants’ usefulness in the landscape.
Lydian Broom is native to the Balkans and western Asia, a part of the world with a similarly high, dry climate. It’s hardy to zone 4, in spite of what some websites will tell you. (I’ve seen it growing in Colorado Springs at an elevation of 6,500 feet. The plants tolerate drought and any soil that drains well. Deer tend to avoid browsing on the leaves (unless they’re really hungry, when nothing is safe).
In general, little maintenance is needed, there may be some tip die-back after a particularly harsh winter, which will need to be trimmed. Pinching back the branches a bit after the flowers are finished will keep the shrub bushy and tidy.
Good companions will have similar cultural needs, and leaves or blossoms that can stand up to such a brilliant yellow—think gray or golden foliage, and flowers in similarly deep hues. I’m pairing mine with purple catmint, dark purple irises, Karl Foerster Feather Reed grass, and Angelina stonecrop for a sunny, low-water garden with year-round interest.
Dyers Broom (Genista tinctoria) is another deciduous broom that’s welcome in my garden. Slightly larger, at two to three feet, the shrubs are a bit less compact, but still put on the same impressive show in June and July. Hailing from Southern Europe and southwestern Asia, this broom has preferences similar to Lydian broom—full sun, low to average water, and well-drained sandy or gravelly soil—but tolerates more moisture, and can be invasive in areas with wetter climates. That’s not a problem in Colorado; if I had room for a larger shrub, I wouldn’t hesitate to plant it.
Genista depressa is a lesser-known broom that forms low-growing mats, making it well-suited for rock gardens. Like the other Genistas, it requires full sun and very well-drained soil. The showy yellow flowers, appearing in May and June make me wish I had a scree slope—or at least a trough garden—so I could grow a plant for myself. At least I can visit the specimens at the Denver Botanic Garden.
Gardening in Colorado may be challenging, but there are perks as well. One definite plus is being able to include brooms in our landscapes.