Question: I have heard that brooms are invasive plants, and having just driven to the coast along yellow hills, I believe it.
Published in the Contra Costa Times on March 29, 2008
Question: I have heard that brooms are invasive plants, and having just driven to the coast along yellow hills, I believe it.
I love the color, but what can I plant instead of broom? If the plants are such a problem, why are the nurseries selling them?
Answer: There are a number of plants called broom that are invasive pests in California — and in other Mediterranean climates around the world. These plants include Cytisus scoparius, C. striatus, Genista monspessulana, Retama monosperma and Spartium junceum. Their common names can be Scotch broom, striated broom, French broom, bridal veil broom and Spanish broom.
Forming large bushes, these shrubs are covered in the spring with bright yellow to deep orange pea-shaped flowers that produce copious quantities of viable, hard-coated seeds that may be able to remain viable for up to 80 years. The seeds get moved around by vehicle tires, equipment, animal hooves, shoes, and can be washed downslope by winter rains.
Thickets of the shrubs can grow so densely that native plants cannot compete, and by 2003, almost 2 million square feet of the state in 23 counties had been invaded. Brooms block light, deplete water resources and are unpalatable to wildlife.
There are many excellent, non-invasive native and non-native alternatives to broom. Encourage your local nurseries to carry these plants, and not to sell broom. Photographs and more detailed information can be accessed at www.plantright.org.
Here is a list of alternatives, but it is not a comprehensive list by any means:
Ribes aureum (golden currant): This deciduous California native is native to moist areas, but does well in sun and shade, and is quite drought-tolerant. The fragrant flowers are bright yellow, and are followed by delicious berries except in mild climates. The flowers attract hummingbirds and native bees.
Fremontodendron californicum (California flannel bush): The large, waxy, bright yellow blooms of this evergreen plant can stop traffic. The plants grow rapidly and can become quite large, with dramatic, angular growth habits in full sun locations. Soils can be infertile, but should drain well. California flannel bush is short-lived, but spectacular. It does not tolerate summer water.
Tagetes lemmonii (bush marigold): Bush marigold has very aromatic foliage and bright yellow-gold flowers that bees and butterflies love. The plants are evergreen in mild climates, where it may bloom year-round. Bush marigold is deer-resistant, likes occasional water in the summer and wants to live in full sun. The plants may grow to 6 feet if not pruned.
Phlomis fruticosa (Jerusalem sage): This is one of those plants thats common name makes no sense. This is not a sage, nor is it from Jerusalem, but that aside, it is a lovely, hardy plant that deer avoid. The foliage is a soft gray-green, and the flowers emerge on stalks in the mid-spring with whorls of butter-yellow and white blossoms.
Halimium lasianthum (Lisbon false sun-rose): This is an excellent alternative for coastal gardens. The small, evergreen shrub is covered with sunlight yellow, five-petaled flowers accentuated with a dark blotch in the center. The plants grow and bloom quickly, and can be found in better nurseries.
Bethallyn Black is director of the Contra Costa Master Gardeners, a program associated with the University of California Cooperative Extension and supported by Contra Costa County. Reach her at bblack@ucdavis.edu, or 925-646-6586. General questions for the Master Gardener should be sent using our Question Form