Cytisus or Broom
Free Blooming Shrubs for sunny location
Leaf losing and evergreen hardy and tender shrubs which are very beautiful when in bloom in spring and summer; they bear pealike flowers of various colors. About fifty species are known; they are natives chiefly of the Mediterranean region and the Canary Isles. The name Cytisus is from kytisos, the Greek name for a kind of Clover. These shrubs belong to the Pea family, Leguminosae.
Sowing Seeds and Taking Cuttings. The Cytisus thrive best in well-drained, rather light land, but heavy ground can be made suitable by adding compost and sand or grit. They must have the sunniest possible position. The species or wild types of Cytisus are propagated by seeds sown as soon as they are ripe in pots or flats of sandy soil in a cold frame or greenhouse. Some gardeners believe it is advantageous to soak the seeds in water for 24 hours before sowing.
As the varieties do not come true from seeds they should be propagated by cuttings placed firmly in a bed of very sandy soil in a cold frame in August, or in similar soil in a shaded place out of doors and covered with a bell jar. The cuttings are made from firm summer shoots, 2-4 in. long, with a thin heel or piece of the older wood attached. The numerous named varieties may be propagated by grafting on stocks of Laburnum raised from seeds. The Laburnums are grown in pots and grafting is done in early spring in a propagating case in a warm greenhouse.
Planting and Pruning. Brooms should be grown in pots until large enough for planting in their permanent positions as they do not transplant very successfully from the open ground. For the first two or three years after propagation, whether by seeds, cuttings or grafting, the fresh shoots on the young plants should be cut back several times during the summer to ensure well-branched plants. In subsequent years most kinds of Brooms can be kept shapely by pruning the one-year-old shoots, but they do not produce new shoots freely when pruned back into the old wood. Those kinds which flower in April, May and June, should be cut back immediately the blossoms fade, two thirds of the length of the previous season's growths being cut off; those kinds which flower during July and August should be pruned in early spring, just before new growth recommences. When a bush becomes tall and bare-stemmed, it is better to dig it up and plant a young one rather than to prune back into the old wood.
Cytisus are good shrubs for lawn beds, sunny shrub borders, banks and rock garden slopes. The most popular kinds are the numerous varieties and hybrids of Cytisus scoparius, the Scotch Broom. They average 4-6 ft. high, and flower in May and June.
Spring-flowering Cytisus. A group of European-raised Cytisuses are extremely fine. Cytisus scoparius Golden Sunlight, with large golden-yellow blossoms is an object of great beauty. C. scoparius Andreanus, the first plant of which was found growing wild in Normandy, has crimson and gold blossoms; Firefly and Dragonfly are of richer coloring. Burkwoodii is crimson; Cornish Cream, cream colored; Dallimorei, rose purple, and Donard Seedling, crimson and yellow; Lady Moore, red and yellowish buff; Lord Lambourne, crimson and primrose, and there are many other equally lovely kinds. These hybrids and improved varieties will not stand severe winters.
Cytisus albus (multiflorus) is the White Portugal Broom, one of the most attractive of spring-flowering shrubs. C. Battandieri is a remarkable shrub or small tree from Morocco: it grows 12 to 15 ft. high. The leaves have a silvery appearance and the fragrant, golden-yellow flowers are in erect racemes, which are produced along the branches in June. It flourishes in ordinary soil but is not hardy North. C. praecox has primrose-yellow flowers of rather unpleasant odor.
Summer-flowering Cytisus. Among those kinds which flower from midsummer onwards are C. ratisbonensis, 3-4 ft. high, yellow; C. sessilifolius, 5-6 ft. with yellow flowers on slender stalks; and C. nigricans, a useful kind which bears yellow flowers freely from July to September.
For the Rock Garden. A representative selection of rock garden Brooms includes the following: C. kewensis, trailing shoots thickly covered with primrose-yellow flowers in May; C. scoparius pendulus, large yellow flowers; C. scoparius sulphureus, low growing, flowers pale yellow; C Beanii, small golden-yellow flowers; C. purpureus, a spreading dwarf shrub with rosy-purple flowers; C. decumbens, a prostrate shrub only a few inches high with yellow blossoms, and C. Ardoinii, a pretty shrub from the Maritime Alps, with bright yellow flowers, that is not hardy in the North. All bloom in April and May.
For the Greenhouse. From the Canary Isles, northern Africa and other warm districts of the Mediterranean, Brooms which are not hardy in the North have been introduced. In the South and West they can be grown out of doors but elsewhere the protection of a greenhouse is necessary.
The best known is the popular Cytisus (Genista) fragrans, with fragrant yellow blossoms, a favorite spring-flowering greenhouse shrub, and grown in market nurseries by the thousand for sale in florists' shops.
The variety elegans is distinct in having grayish-green foliage. C. monspessulanus, the Montpelier Broom, is a graceful evergreen or semi-evergreen, 6-10 ft., with yellow flowers early in May.