Plants Have Minds of Their Own

Ceanothus 'Yankee Point'

Ceanothus ‘Yankee Point’

Plants have minds of their own. No matter how much you think you know about them, they will surprise you time and again.
Sometimes the surprise is a happy one. For example, you will hear that a certain plant, such as rhododendron, will just not grow in alkaline Valley soil since it is native to East Asia, where the soil is highly acidic. Then you plant one, and it thrives, as I once saw a friend’s rhododendron do. Growing in dappled light in front of a north facing living room window in Sherman Oaks, it reached over five feet in height with a girth of four feet, and was covered with deep pink flowers in late winter and early spring.
But sometimes the surprise is not so happy. You plant a California native Ceanothus (see-a-NO-thus) in perfect soil with lots of sun and it flounders. Ceanothus, with lush foliage and blue flowers, and with forms ranging from arboreal shrubs to ground cover mats, appears on every list of drought tolerant plants.
A friend of mine who lives in Westwood and is an ardent gardener had been experimenting with Ceanothus (California lilac) for years with much success. Wherever he planted it, it thrived, even if he never happened to try growing it in all-day sun. Then, a year and a half ago, he covered a south facing slope in front of his house with Ceanothus griseus horizontalis ‘Carmel Creeper.’ He planted 40 one-gallon plants and, almost from the beginning, some of them displayed signs of displeasure. On one corner of the slope, three plants grew a bit, stagnated, and eventually died. But the rest of the plants were robust and, by this summer, had nearly blanketed the slope.
Suddenly, about two months ago, the rest of the Ceanothus started to die. The plants displayed tell-tale signs of root rot, a common and fatal disease of Ceanothus where soil moisture is excessive. Leaf color began to fade and soon shoots shriveled and died. Yet, prior to planting, the original clay soil on the slope had been excavated to a 12-inch depth and replaced with what people in the landscaping trade call “fifty-fifty.” This is a mix available in bulk at places such as Valley Sod in Sepulveda, Soil and Sod Depot in Pacoima, and American Soil Amendment Products in Simi Valley.
Fifty-fifty is one half top soil, consisting mostly of sand, and one half organic amendments, consisting mostly of shredded and composted tree prunings (wood, bark, and leaves).
My friend and I speculated that the roots of the Ceanothus, once they reached the original clay soil, became infected with the Phytophthora fungus that causes root rot.
Yet, ‘Carmel Creeper’ is one of a select number of California natives that is actually recommended for clay, as long as the soil is kept bone dry or nearly so. Watering on the slope had been done exclusively with a hose, and no more than once every other week. We also reasoned that since ‘Carmel Creeper’ is native to coastal Northern California, it might be stressed when growing in full sun in Southern California, even though the climate in Westwood is comparatively mild.
Then we began to compare notes on all the Ceanothus plantings we had done and realized that full sun, south-facing plantings had always been problematic, whereas sun-protected, lightly shaded or unshaded but north-facing plantings had always thrived.
At this point, I would like to turn to you readers and ask you to share your Ceanothus experiences. Has anyone had success growing it in southern, full sun exposure? In what type of soil is it growing? Since water rationing appears to be here to stay, it is important to know the limits of Ceanothus, since it is often recommended for sunny slopes and, at least where its ground cover types are concerned, as a lawn substitute.
Nick Kurek, of Granada Hills, e-mailed me about rosemary shrubs (Rosmarinus officinalis), planted on a 2,500-square-foot slope, which have been yellowing and dying back in recent years. I started to commiserate with him on the condition of his plants until I learned that they are 46 years old! That’s a phenomenal age for rosemary or any other shrub.
I asked about his soil and learned that it is a granitic, sandstone type, and this could explain the longevity of his rosemary. Rosemary might be the Mediterranean equivalent of Ceanothus ‘Carmel Creeper’ since it is native to fast-draining slopes from Portugal to Greece that face the sea. Kurek says he can easily dig down 12 inches into his slope but that he needs a pick to go deeper.
He waters with rotary sprinklers once a week for 15 minutes, twice a week during hot spells.

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