Sweet broom (Cytisus x spachianus), also known as Easter broom, is a flowering deciduous shrub with upright arching branches. Hardy in U.S. Department of Agriculture plant hardiness zones 8 through 10, sweet broom produces fan-like leaves and fragrant golden yellow blossoms that appear in late winter to early spring. Known for its deep, extensive root system, sweet broom flourishes in dry hillside plantings. Water-wise borders, ground cover and containers benefit from its colorful blooms.
Plan your planting or container placement to allow enough room to accommodate this fast-growing plant. At maturity, sweet broom reaches 6 to 8 feet tall and 5 to 6 feet wide. Locate sweet broom in an area where it receives light shade to full sun. It flowers beset in bright indirect sunlight coming from the south, east or west. If your winter temperatures regularly drop below 15 degrees Fahrenheit, give sweet broom a sheltered, south-facing location. Sweet broom plants tolerate poorer soils outdoors and can help stabilize slopes.
Soil and Nutrient Requirements
Container-grown sweet broom needs a fast-draining potting soil to keep roots supplied with plentiful oxygen. A general potting soil can be improved by adding equal parts of sand, perlite and peat moss. Feed container plants every two weeks with a water-soluble, all purpose fertilizer such ass 15-15-15. Mix 1 tablespoon of fertilizer per 1 gallon of water. Garden-grown sweet broom asks for porous, well-drained soil. Feed your plant a granular, slow-release, 15-15-15 fertilizer once in early spring. Broadcast 3 tablespoons of fertilizer per 4 square feet, and water the area thoroughly.
Water and Pest Control
Use a regular watering schedule during the first growing season until the plant has developed a deep root system. Water deeply and thoroughly when you water, then allow the soil to become moderately dry between waterings. This helps encourage deep, healthy roots. In dry climates, mist the plant occasionally with warm water during the flowering season. Take time when watering to inspect plants for whiteflies and spider mites, which are fond of sweet broom plants and can be found on the underside of foliage. If found, spray the affected areas with a ready-to-use pesticide marked for use with the insects. Repeat the treatments every two weeks until the plant is clear of pests. Always wear gloves and protective eyewear when spraying.
Pruning and Propagation
Prune your sweet broom when it has finished blooming by trimming back all the branches by about one third. As the plant matures, cut out the oldest, less-productive, woody stems to enhance flowering on younger branches. Use sharp bypass pruning shears and wear gloves. Prevent the spread of disease by sterilizing your pruner blades with household disinfectant before and after your pruning session. Propagate sweet broom by stem cuttings in spring or summer. Place the cuttings in a mixture of moist peat and perlite, and cover the container with a plastic bag secured by a rubber band to keep the moisture in. Place your pot in indirect sunlight or under a fluorescent light. Transplant when the cuttings have produced roots.
Many species of broom plants are considered invasive and are banned in certain parts of the United States. Sweet broom is a hybrid developed to be sterile and non-invasive. Still, the plant's aggressive growth rate warrants vigilance in warmer climates. If broom plants exhibit invasive qualities in your growing region, consider using a non-broom alternative in your plantings.