Members of the pea family, brooms display yellow pea blossoms that make them favoured in gardens in sunny, arid soil conditions. The common name broom describes plants in the genera Genista and Cytisus, both comprising species native to Europe, western Asia and northern Africa.
Although specific timing of flowering varies by species, brooms in both the Genista and Cytisus plant genera flower mainly late spring to early summer. Some species, such as Cytisus spachianus, blossom in late winter to early spring. Genista aetnensis blooms in mid- to late summer.
Broom shrubs produce their flowers on branches that grew last year and the current year. If you must prune, do it in late winter before the new spring growth begins. One exception to this rule is Scotch broom (Cytisus scoparius), which must only be pruned after flowering ends in very late spring. Ill-timed pruning can result in no flowering that year.
Brooms do not tolerate heavy, severe pruning. Only lightly trim branch tips to better shape plants, or to remove dead branches. Never cut into lowest, old wood -- plants will not rejuvenate.
- "A-Z Encyclopedia of Garden Plants"; Christopher Brickell and H. Marc Cathey, eds.; 2004