“Due to the recent fires, it’s been recommended that we remove our last palm tree, which is by our pool. I have a narrow planter in that location. I would like a new drought-tolerant, fire-resistant tree or bush whose roots will not be a detriment in that location. During the summer, the area gets morning sun (approximately 6-8 hours) and afternoon shade. Any ideas for an interesting centerpiece for that planter?” – Karen Mansky

The caveat should first be made that the sort of conflagrations we recently experienced could burn any tree to the ground. When conditions are exceedingly dry and the heat generated by a wildfire reaches a certain point, every plant species will incinerate.

Palm trees, nearly all of which are drought tolerant with roots that are not generally a threat to adjacent hardscape or pools, are widely considered to be fire resistant as long as they are properly maintained. This means that fronds should be cut flush with the trunk since frond stubs are platforms where flying embers can land. Needless to say, allowing dead fronds to accumulate on a palm tree is an invitation to disaster. Palm trees with fibrous trunks should be vigorously pruned and stripped of all fibrous tissue. The City of Escondido lists every palm tree found in Southern California gardens on its list of fire-resistant species, although they are accompanied by a warning to be planted between 10 and 30 feet (depending on the species) from any structure, clearly an indication that their bursting into flame is always a possibility.

Three highly attractive palms are generally considered fire-safe as long as their dry fronds are removed in a timely manner. Under cultivated conditions, all grow 30-40 feet tall. Mexican blue palm (Brahea armada) is a stunning specimen with dusty blue fronds; Bismarck palm (Bismarckia nobles) has unusual silvery-blue fronds that stand out majestically in any garden; pindo or jelly palm (Butia capitata) has grayish green fronds, sweet-smelling flowers and edible fruit. Sago palm (Cycas revoluta), although not a true palm, is another species worthy of consideration as a centerpiece for your planter. You would, however, want to procure a mature specimen, at least a few feet tall, since sago palm growth is exceedingly slow, averaging about one inch of trunk elongation per year.

Arboreal succulents are worthy of consideration since they are drought tolerant and fire resistant with non-invasive root systems. Tree aloe (Aloidendron/Aloe barberae/bainesii) immediately comes to mind. This is an unforgettable beauty with its sculptural branches and curvaceous trunks, often several to a tree. The most glorious local display of these trees is to be found at the Getty Center terrace garden in Brentwood, where a mass of them are planted near African candelabra (Euphorbia ingens), another magnificent succulent tree. Both of these species top out at around 30 feet in Southern California.

New Zealand flax (Phormium) is a clumping plant with swordlike leaves that reach 9 feet in length in some cultivars. The classic varieties have reddish-bronze foliage, but many colorful types with green and yellow or cream and pink variegation are encountered. Although the plant will grow as far north as Valencia and Newhall, at least, and will adapt to most exposures, it is best suited to partial or half-day, morning sun in the Santa Clarita and San Fernando valleys. It will survive placement in full sun in these locales but suffers burnt foliage as a result. The closer it gets to the ocean, or the further south you go from Los Angeles, the more direct sun New Zealand flax can take. San Marcos Growers (smgrowers.com) has dozens of New Zealand flax cultivars should you decide to special order them through a retail nursery they supply in your area. 

The grass palm (Cordyline australis) resembles New Zealand flax when it is small, but eventually reaches 20 feet or more in height. It is more cold-hardy than New Zealand flax and does a better job of holding its foliar color which, depending on variety, may be bronze, reddish-purple or pink striped. With their radiating clumps of thin leaves, grass tree (Xanthorrhoea preisii), native to Australia, is a stunning complement to New Zealand flax and grass palms, as is desert spoon (Dasylirion wheeler), native to Mexico and the American Southwest.

Yucca linearifolia (to 4 feet tall) and Yucca rostrata (to 10 feet tall) are dazzling, slow-growing specimens with very thin leaves that develop into massive radiating clumps on the ends of thatched trunks so that, from a distance, they could be mistaken for palm trees. Make sure to keep the thatch removed to reduce the flammability of these species. 

Last but not least, MacDougall’s giant century plant (Fucraea macdougalii) has spear-shaped leaves that reach six feet long. Despite its name, the plant lives around 40 years, reaches 15 feet in height, and has an unmatched aristocratic presence in the garden.

The roots of all species mentioned above should not crack your swimming pool, although there is always some possibility that could happen. To be extra safe, install a root barrier along the side of the pool where you plant your tree. Modular pieces are snapped together to match the specific dimensions of the barrier you have in mind.

California native of the week: California native sea lavender (Limonium californicum) or Western marsh rosemary, is a tough perennial found in coastal marshes from Oregon to Baja California and thus requires regular water to grow to its full potential. It is so moisture-friendly, in fact, unlike the preponderance of natives, that it will even grow in soil where drainage is poor. Its flower stalks bear delicate papery flower clusters in lavender-blue and white — suitable for everlasting flower arrangements — and reach 18 inches tall. Rhizomes are responsible for this species’ persistence and spread where moisture is freely available. Butterflies, bees, and other insects are magnetized by its flowers, making it an effective pollinator plant, while its salt tolerance makes it a sensible selection for gardens facing the sea. This species has no fragrance; its lavender appellation simply acknowledges its flower color while its rosemary epithet indicates its seacoast habitat. “Rosemary” combines two Latin words: ros = dew, and marinus = sea, referencing the drops of seawater, resembling dew, that splash on the plant.

Do you have a drought-tolerant succulent tree or large shrub to recommend? If so, send your recommendation to [email protected]. Your questions and comments, as well as gardening conundrums and successes are always welcome.

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