All About Broom Shrubs – 10 Best Types
Broom shrubs grow very quickly and can be very small to large. Plant seeds are spreading and sprouting quickly, making the plants pretty invasive.
Due to this rapid growth, native species are threatened by the plants. Root systems on brooms are wide and branching, and their stems are thick and hardy.
In addition to the common Scotch and Spanish broom shrubs, there are several varieties of broom shrubs, which are commonly used for erosion control.
History of Broom Shrubs
The common broom shrub, as with many of the UK’s native plants, is steeped in history and folklore, and gave its name to a royal dynasty – its original Latin term, Planta genista, was adopted by the Plantagenets.
Geoffrey of Anjou, father of Henry II, put a sprig of broom in his helmet when going into battle. A spray of broom was the badge of Henry II and the plant made its first official heraldic appearance in England on the Great Seal of Richard I, the Lionheart.
The name comes from the old English word brom, meaning coarse shrub, and it was one of many plants employed to sweep the floor, although tradition forbade its use for such humble tasks when it was in flower.
Varieties of Broom Shrubs
Cytisus x kewensis, is a variety of brooms that was raised at Kew more than 100 years ago, has creamy yellow broom flowers, and reaches twelve to sixteen inches (30-40 centimetres) in height. As it can spread more than six feet (two metres), it looks marvellous tumbling down a slope.
Open heathlands in June & July are often awash with the delicate charms of the broom plant. They produce billowing masses of fragrant flowers in late spring and early summer. With their two lateral petals (wings), an upright dorsal petal (the standard) and two lower petals (the keel) – and as their group name, Papilionaceae, suggests – they resemble butterflies.
The 50 or so species, native to many parts of Europe, North Africa and Asia Minor, have spawned numerous hybrids, giving great varieties of broom shrubs to suit every garden.
Cytisus multiflorus, white Spanish broom, is a fast grower. Erect, with greyish shoots, it produces masses of tiny white flowers in early summer and makes a wonderful specimen in a white garden.
Another broom shrub, native to the UK, Cytisus scoparius, has butter yellow broom flowers smelling of vanilla, and provides a delightful display in June and July, while its green branches also bring colour to the garden in midwinter. Growing to three feet (one metre) in a year, it makes a useful starter in borders before slower growing shrubs get established.
Cytisus nigricans, a yellow flowered erect shrub, takes the flowering brooms into late summer and early autumn.
Cytisus battandieri, the pineapple, or Moroccan, broom, is in a class of its own. It’s a tall open bush with large silvery leaves and dense spikes of pineapple scented yellow broom flowers that appear in early summer. Slightly tender in northern gardens, the broom shrubs can be trained as wall specimens but need pruning after flowering to maintain their floriferous habit.
Smaller species, such as the popular prostrate yellow flowering broom, Cytisus procumbens, are suitable for the front of a border or rock garden.
The semi-prostrate Cytisus albus produces a main flush of creamy yellow broom flowers in early summer and then continues to flower sporadically until autumn.
For something really tiny, try Cytisus demissus. No more than four inches (ten centimetres) high, it comes from Mount Olympus in Greece and has exceptionally large flowers for such a small plant. Produced in May, they are yellow at first, then darken to orange with a brown keel and are very attractive.
Chamaecytisus purpureus, the purple broom shrub from central and southern Europe, widens the colour spectrum. An attractive low broom shrub (eighteen inches or 45 centimetres), it produces pretty, lilac purple flowers in May.
Some broom shrubs are more tender than others, so make enquries before planting. The tender Cytisus maderensis var. magnifoliosus, makes a good conservatory plant for its scent as well as its bright yellow broom flowers.
Uses for Broom Flowers
Are Broom Flowers edible?
Common broom flowers are edible, either raw in salads, or pickled. The green shoot tips were used during the Second World War as a mild diuretic – a practice not recommended today, as, in large quantities, the active constituent of broom, sparteine, is poisonous!
Today, broom may no longer be used to sweep with or be eaten, but it still has its uses.
Its strong roots help to bind banks (including sand dunes, as it is salt tolerant). The wood of larger specimens has been used as a valuable veneer and, in Madeira, the branches are still sometimes used for basket work.
The hybrid brooms, more often seen in our gardens, are grown for show.
Cultivating Broom Shrubs in a Garden
Brooms are best introduced to the garden as young, container grown plants. Think long and hard before putting them in as they do not take kindly to being transplanted.
Choose a sunny position, sheltered if possible, although they will tolerate a windy site if staked.
In some instances, they have been used as wind breaks and as a nurse crop around young saplings. One advantage is that rabbits are not partial to them.
Most of the species are lime tolerant but Cytisus scoparius and Cytisus multiflorus and their mixed offspring (most of the hardy hybrids) do not last long on poor, shallow, chalky soils. They prefer neutral or add soils, or deep loam over chalk. Larger hybrid brooms benefit from pruning.
The majority flower on the previous year’s growth and long shoots should be cut back hard after flowering, taking care not to cut into the older wood. Broom shrubs that have become leggy, bare and hard wooded are best discarded. The few that produce flowers on the current season’s growth, such as the late flowering C nigricans, need pruning in the spring.
Broom shrubs are, in general, not long lived, so it may be worth propagating favourite varieties early on. Species can be propagated by semi-ripe cuttings in summer or by seed in April. Hybrids need to be propagated by semi-ripe cuttings in late summer.
Most of the varieties of broom shrubs do not need fertilisers or manures as, being in the legume family, they make their own. They have a very handy relationship with a friendly soil bacteria, the rhizobia, which make their home in the roots.
The plant, as with all members of the pea family, gives the rhizobia a home and a supply of sugar, and, in return, the bacteria pay their rent by changing nitrogen gas (which accounts for about three quarters of our air) into plant fertiliser. What more could you ask for?