Few people could fail to notice a Cytisus in full flower, covered with masses of pea-like blooms. One of the “broom” genera (the other main genera being Genista and Spartium), there are some 30 species of Cytisus. Originally the genus was much larger, but a few years ago a significant number of species (mainly low and prostrate forms) were separated into their own genus, Chamaecytisus.
There are both deciduous and evergreen forms of Cytisus, but many have practically leafless shoots, with a light, grass-like quality that offers a useful contrast to nearby broad-leaved shrubs. The range includes prostrate shrubs to bushes of 4m or more in height.
Most garden soils are acceptable for these plants, although the extremes of acid and chalk are best avoided. All require good drainage and full sun.
Young plants must be container-grown to avoid root disturbance and, once established, they do not take kindly to transplanting. Any pruning is best done after flowering by cutting back, by up to two-thirds, the previous summer’s growth. Once the wood has hardened it does not respond to pruning, so leggy specimens, especially of C. scoparius and its forms, are best replaced with young plants.
C. x praecox is the most popular of the brooms. A small shrub, it can begin to bloom any time from mid-spring: tiny buds appear all the way along the stems, each one opening into a very fragrant pea-like flower.
Brooms have a variety of uses — the smaller varieties can be planted up in containers, while the larger hybrids can be incorporated into beds and borders. Solitary specimen planting works well for shapely specimens such as C. x praecox, while
C. x kewensis Award of Garden Merit (AGM) makes a good ground-cover plant.
Bold splashes of colour can be introduced into mixed borders by siting the taller kinds, which tend to become leggy, towards the back.
C. battandieri AGM, although included in this genus, is quite a different form. It grows to become a tall shrub of 4m or higher, with upright clusters of bright yellow flowers in July, which have a sweet fragrance akin to pineapple. It makes a good free-standing specimen plant, but thrives best with the protection of a wall.
This plant has silky grey-green leaves, similar in shape to Laburnum, to which Cytisus is closely related. In fact, a useful cross-generic graft (x Laburnocytisus ‘Adamii’) is an excellent but rarely seen tree with three types of flowers on a single plant: purple Cytisus-like flowers, yellow Laburnum-like flowers, and other pea-like flowers of yellow and pinkish-purple shades.
These plants are generally pest- and disease-free, but they dislike being disturbed once planted, which can result in slow establishment.
What the specialists say
Brian Phipps, director, Goscote Nurseries, Leicestershire “Brooms are very useful for borders and containers, but they aren’t particularly high sellers across the year. This changes when they are in flower, however -— suddenly they become very saleable.
“We run a plant nursery and regularly supply small landscape businesses, but there doesn’t seem to be too much of a call for Cytisus, which is a shame. We really should educate the gardening public to grow these plants more.
“I think part of the reason for the lack of interest is maintenance. Although they are not particularly demanding, they do need to be pruned every year if you are to get the best of the flowers. By doing this you will prevent them from getting too leggy and prolong the life of the plant.
“By far and away the best-selling Cytisus is the pineapple broom — C. battandieri Award of Garden Merit (AGM). It needs a sunny position and is perfect for growing close to a wall for shelter. It flowers in early summer, so should be pruned after flowering like the others. Unfortunately, it can be a little on the tender side and could suffer in a really bad winter. We therefore sell these plants with a warning note.”
Peter Chapman, managing director, Perryhill Nurseries, East Sussex “Cytisus is a strong seller — but only in season, when it becomes very much an impulse purchase. We have mainly retail customers, but also a few landscapers who use brooms for instant filler colour when they’re in season.
“The best form now is C. x kewensis ‘Niki’ which, although it is slow to sell, when it’s ready it is very good, producing yellow flowers in May. For us, the clear best sellers are the more popular forms of C. x praecox, such as ‘Warminster’ AGM, ‘Allgold’ AGM and ‘Albus’. We occasionally get asked for C. ‘Minstead’ and x Laburnocytisus ‘Adamii’, the grafted chimera, but it isn’t always available.”
Jonathan Savage, planteria manager, Scotsdale Garden Centre, Cambridge “These plants are best sold in blocks of colour. We sell 85 per cent of all Cytisus plants during the six- or eight-week period in spring when they are in bud or in flower.
“We still operate on an A-Z shrub section, but the Cytisus is one of the few plants we will display separately when in season, and in far greater quantity than other flowering shrubs. For us, the burgundy-red and the white-cream coloured varieties sell best. During the main part of the year we’ll keep only a core of varieties as they don’t sell in particularly high number when just green plants.”
Species and cultivars
• C. ‘Apricot Gem’ is a compact, semi-evergreen shrub with upright stems and masses of orange-yellow flowers. It grows to 1.2m tall.
• C. ardoinoi Award of Garden Merit (AGM) is a deciduous, hummock-forming broom, reaching just 10cm in height. It is ideally suited to rock garden and containers and has bright-yellow flowers.
• C. battandieri AGM is a tall shrub with grey-green stems and grey leaves. Its flowers resemble cones of rich yellow and are pineapple scented.
• C. x beanii AGM is a dwarf deciduous broom growing to just 30cm high. Neat and compact, it’s smothered in golden-yellow flowers in late spring.
• C. ‘Boskoop Ruby’ AGM is small and rounded with deep crimson flowers.
• C. ‘Burkwoodii’ AGM is larger-growing and vigorous. It produces cerise flowers with deep crimson “wings” edged with yellow.
• C. ‘Compact Crimson’ produces masses of crimson flowers that clothe the branches in early summer.
• C. decumbens is suitable for rock gardens as it reaches just 30cm in height. It needs good drainage.
• C. ‘Dukaat’ is a compact evergreen shrub with bright yellow flowers in spring.
• C. ‘Firefly’ displays flowers of yellow and brownish red.
• C. ‘Fulgens’ carries orange-yellow and deep crimson flowers in May. Tiny green leaves are held on long thin stems. It grows to 1.5-2m high.
• C. ‘Golden Cascade’ is semi-weeping with golden yellow flowers.
• C. ‘Hollandia’ AGM displays pale cream and cerise flowers on arching branches.
• C. x kewensis AGM is a dwarf deciduous broom growing to just 30cm high. It has cream flowers in late spring.
• C. x kewensis ‘Niki’ produces yellow flowers in May.
• C. ‘Killiney Red’ displays slender green shoots carrying masses of pink/red flowers.
• C. ‘Killiney Salmon’ is salmon-pink, usually growing slightly wider than high at 1.2m.
• C. ‘La Coquette’ has flowers in a mixture of rose-red, orange-red and yellow shades in May/June, with a height of 1.5m.
• C. ‘Lena’ AGM is a compact, spreading shrub with deep red and yellow flowers.
• C. ‘Luna’ carries large flowers in shades of yellow tinged with red.
• C. ‘Minstead’ features small flowers that are white flushed with lilac.
• C. nigricans ‘Cyni’ produces bright yellow flowers in June, later than most other varieties.
• C. x praecox is bushy, with cream flowers in April/May.
• C. x praecox ‘Albus’ displays white flowers in May.
• C. x praecox ‘Allgold’ AGM features strong yellow flowers and is long-lasting.
• C. x praecox ‘Lilac Lady’ produces pale green stems and small, dainty lilac flowers.
• C. x praecox ‘Warminster’ AGM is one of the best, with deep cream flowers. It grows to 1.5m or more.
• C. ‘Red Wings’ has deep velvety-red and yellow flowers.
• C. scoparius bears masses of bright yellow and scarlet flowers in late spring and early summer; height 1m.
• C. scoparius ‘Cornish Cream’ has creamy yellow, pea-like, flowers in May; height up to 2m.