"It's a beautiful tree," they say of the eucalyptus, "but just try to plant anything under one!" The myth goes that the resinous litter of a eucalyptus tree kills just about anything grown near it. As a landscape designer, I deal with this problem all the time, especially in Del Mar, Rancho Santa Fe, and Scripps Ranch. So I know it is possible to garden beneath these wonderful trees.
Eucalyptus trees are a cherished part of the scenery in California, from the Napa Valley, where they impart a distinctive minty fragrance and taste to some of our finest Cabernet Sauvignon wines, south to the Mexican border. In some communities in San Diego County, such as Scripps Ranch and Rancho Santa Fe, eucalyptus are the dominant species of tree. Their graceful blue-gray silhouettes and resinous aroma help to define the distinctive characters of these towns.
Eucalyptus trees are not native to California. Because they are native to sections of Australia which have similar climates to California (subtropical, desert and Mediterranean), they grow happily here, tolerating our low rainfall and sometimes-poor soils.
Eucalyptus trees were first brought to California by botanists in 1856. The trees were planted for firewood and also to provide windbreaks for orchards and vineyards. Later, around the turn of the century, magnates of the Santa Fe railroad, who believed that the wood would be ideal for railroad ties, planted extensive groves of the 18 best-suited varieties. They were encouraged by then-president Theodore Roosevelt's reforestation program. Three million seedlings were planted in Rancho Santa Fe alone! As most of us know, the wood proved to be unsuitable to hold the spikes in place and the trees were never used for their intended purpose.
Eucalyptus in the landscape
Nonetheless, eucalyptus were then and are today appreciated for their landscaping uses. Many eucalyptus species have beautiful forms and textures. Some of the flowers are striking in shape and have brilliant colors. Many leaf-forms and seed pods are sold by florists for arrangements. These trees all have extensive networks of large surface roots; a few varieties have deep tap roots as well. This combination makes them ideal candidates for holding soil on our many fragile slopes where watering is difficult and not advisable. The root system also allows these trees to tolerate our infrequent seasonal rainfall and infertile, rocky soils. Finally, the eucalyptus tree, planted and cared for properly, is an astonishingly fast grower. According to the Sunset Western Garden Book, some species grow 10 to 15 feet a year!
There are, though, problems with these beautiful trees and the gardens in which they live.
Many of us with eucalyptus trees are all too familiar with the vast amount of leaf, bark, and branch litter that can be generated by even one of these trees during a howling two- to three-day Santa Ana.
Although the leaves are evergreen, the bark and pods of many species are deciduous and even under normal weather conditions there is a constant rain of litter. Since it is believed that there are toxins in the leaves which, when leached out by watering or rainfall, act as a soil sterilant, prompt clean-up is necessary---at least once a week. (Unless, of course, your objective is weed control around mature plantings. To this end, a neighbor of mine
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trucks in eucalyptus leaves to mulch around his mature tropical landscape, thereby conserving water and choking out weeds at the same time.) Normally, it is not a good idea to include eucalyptus parts in a compost or mulch pile.
Couple the problems associated with eucalyptus litter and the aggressive, wide-reaching root system, which tends to take up available water and food at the expense of other plants, and we end up with relatively few plants that can successfully compete with the trees.
There is nothing quite so beautiful as grass undulating over hilly expanses beneath eucalyptus trees. However, to keep that grass a healthy green, expect to spend a small fortune watering daily.
The list of plants that follows is one which I have accumulated over the past 15 years from personal experience. These plants are mostly from other Mediterranean climate zones so they do not need large amounts of supplemental water once they are established. They can co-exist with the eucalyptus in a garden that is both beautiful and drought tolerant.
Heteromeles arbutifolia (California toyon or Christmas berry) Pittosporum undulatum (Victorian box) Pittosporum eugenioides (Tarata) Rhamnus californica (Coffeeberry) Fremontodendron mexicanum (Southern flannel bush) Rhus ovata (Sugar bush) Rhus integrifolia (Lemonade berry) Rhus laurina (Laurel sumac)
Pittosporum tobira (Mock orange) and its varieties 'Variegata,' and 'Wheeler's Dwarf'
Ligustrum japonicum 'Texanum' (Texas privet) Leptospermum laevigatum (Australian tea tree) Raphiolepis indica (Indian hawthorn) Myoporum laetum
Cistus varieties (Rockroses)
Nandina domestica (Heavenly bamboo)
Rosmarinus varieties (Rosemary)
Sollya heterophylla (Australian bluebell creeper) Echium fastuosum (Pride of Madeira) Crassula argentea (Jade Plant) Cytisus and Spartium varieties (brooms)
Pelargonium peltatum (Ivy geranium)
Osteospermum fruticosum (Trailing African daisy) Gazania varieties Agapanthus orientalis (Lily of the Nile) Achillea varieties (Yarrow) Lavandula varieties (Lavender) Iceplant (most varieties)