Planting on Slopes

silverberry (Elaeagnus pungens) in bloom

silverberry (Elaeagnus pungens) foliage

Slopes.  All over the greater Los Angeles area, from Santa Clarita to the Anaheim Hills, from San Bernardino to Santa Barbara, you have them.  Slopes.

I do not envy people with slopes.  Aside from the chore of planting them, there are the trials of watering, weed control, pruning, and fertilization when it comes to their maintenance.  But then let’s assume that you have finally succeeded in completely covering your slope with vegetation.  Suddenly, you begin to see mounds of freshly milled earth and realize you have a gopher problem.
Even more confounding, you might begin hearing the unmistakable rattling of a certain snake when you occasionally traverse your slope.  Yes, finding the perfect drought tolerant plant specimens to cover your slope means that you will have provided the ideal habitat for a redoubtable reptilian guest.  However, there is an upside to creating a haven for rattlesnakes:  they do a wonderful job of keeping the gopher population under control.
I’m looking for a hardy evergreen, flowering shrub or groundcover for a hillside that gets a lot of sun, but some shade. We want the hill to be covered with the plant we choose, so if it spreads out, even better. But, we’re willing to put in more plants, if it doesn’t spread out a lot. Most important to us is that it has pretty flowers, and nice foliage that doesn’t get woody during the summer. Also important is that it’s fairly low to the ground.  I’m aware of all the low-growing or trailing ceanothus and manzanita options– just not ready to give in and choose either.  Theodore Payne Foundation suggested Santa Cruz Island buckwheat (Erogonum arborescens) and I was also wondering if saffron buckwheat (Eriogonum crocatum) might fit the profile.  Our slope is about 160 feet long and 20 feet high.  Because of its steepness, this is a hillside that we cannot climb and that our gardeners refuse to climb, so plants that need a lot of maintenance are out. We will plant one section that died out (had African daisies, lantana and ice plant) after a sprinkler stopped working– and if we like the new plant, we will slowly phase out old plants with new ones. Ideally, the plant selected would be 12-18 inches tall and more prostrate than mounding.
Leanne Watt, Verdugo Hills
I really like the idea of a mixed buckwheat slope since there are so many types and, between the various species, you have flowers to look at — in white, pink, red, and yellow — throughout the year.  You might have to compromise on your desire for only ground-hugging types, although if you were willing to accept plants that grow up to three feet tall, you should be able to find native buckwheat species with the four flower colors mentioned above.  Santa Cruz Island buckwheat has white flowers that turn to pink and then burnt orange as they fade.  Saffron buckwheat has yellow flowers and silver-gray foliage, red buckwheat (Eriogonum grande var. rubescens) has red flowers, and coast buckwheat (Eriogonum latifolium) has pink flowers.  Buckwheats are famous for attracting butterflies of every description and their flowers are wonderful candidates for everlasting arrangements.  They are evergreen and will self-sow when soil conditions are favorable.
Another native you might wish to consider is brittlebush (Encelia farinosa), although it is definitely a mounding, as opposed to prostrate species.  It may be short-lived, as compared to the buckwheats, but as long as soil drains well seeds should easily self-sow so that new plants should always be coming along. As you go north on the 405 Freeway where it leaves the Valley, look to your right and you will see where brittlebush has completely covered a slope, with silver foliage and, in the spring, yellow daisy flowers.
Acacia redolens ‘Low Boy,’ which does not grow more than one foot tall, is another option.  As a member of the legume family of plants, it makes its own nitrate fertilizer and is therefore adaptable to a wide variety of soil types.  I have seen it flourishing on large slopes in Santa Clarita.  Just make sure you plant the ‘Low Boy’ cultivar as opposed to the plain Acacia redolens species, since the latter will grow up to six feet tall.  A word of caution:  before planting a large slope with a single type of plant, play it safe and plant small areas with different species.  When you see which plant or plants grow best on your slope, plant more of the same.
Tip of the Week:  Silverberry (Elaeagnus pungens), the essence of humility, is one of my favorite plants.  The sages liken a person who engages in continual acts of kindness to a plant that exudes a sweet smell.  The classic plant, in this regard, is the evergreen myrtle (Myrtus spp.), whose leaves, when you brush against them or rub them between your fingers, reward you with a plesant scent throughout the year.  I would also put the silverberry in that category, despite the fact that its flowers, as opposed to its leaves, emit a delicate perfume.  The beauty of silverberry is that it comes into its own in the middle of fall, long after all those well-known perfumed flowers, whether jasmines or gardenias or hybrid tea roses, have faded.  Suddenly, you are walking through the garden and are overcome with a sweet fragrance that stops you in your tracks.  You look around for the source of this olfactory treat and are at a loss to find its source.  Finally, you locate the flowers involved.  They are tiny, cream-colored bells.  Silveryberry foliage is rather plain althrough there is a variegated type with yellow markings. Silverberry also manufactures its own nitrogen and its fruit is edible.  Just make sure to spit out the fibrous seeds.  If you don’t mind a shrub that grows up to fifteen feet tall, you will find silverberry to be an excellent drought tolerant selection for covering slopes as well.

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