With all of our topography in Southern California, I feel as though at least 40% of the design projects I’ve dealt with have slopes to contend with. Many factors have changed the way slopes are handled when it comes to proper plant selection.
In the past, the best plants for San Diego slopes were the tried and true groundcovers, such as Red Apple Ice Plant or Purple Ice Plant. Another popular and outdated plant is Algerian Ivy. Although it is so lush and verdant, it becomes too aggressive taking over fences and choking out other plans. Some of the ice plants have been under attack recently and clients have been forced to rethink major slopes due to the decline of certain plants.
And then there is the water issue. Slopes require a lot of extra water due to gravity. Yes, the Rainbird, overhead spray irrigation has been used for many years with great success, but with the advent of drip irrigation many have chosen the path of least water.
The new mindset for the best plants for San Diego slopes are more shrub-like plants that spread and stay low. These prostate varieties accomplish the need to create a strong root system to hold the slope and avoid erosion. These favored plants come in a variety of sizes and colors to create an interesting mix of plants for any slope.
Best Plants for San Diego Slopes
These plants comprise of Acacia, Rockrose, Lantanas, Rosemary, Grevilleas, etc. These Mediterranean plants still require water 2 to 3 times per week. Another variety of plants for slopes are California Natives , including Manzanitas, Sages, Sagebrush, California Lilacs and Coyote Bush. These non-thirsty native plants will need regular irrigation for 18 to 24 months, and then may be watered as little as one time per month. CA natives require no soil amendments and do require a specific type of bark mulch, one that does not decompose too quickly. Natives do not like too much soil enrichment too quickly.
Here are some links to the plants listed above:
Acacia ‘desert carpet’
Cistus purpurea – Orchid Rock Rose
Cistus ‘sunset’ – Sunset Rockrose
Grevillea ‘king’s celebration’
Lantana ‘new gold’
Lantana ‘lavender swirl’
Lantana ‘white lightning’
Rosemary prostratus – Trailing Rosemary
California Native Plants
Arctostaphyllos ‘emerald carpet’ – Manzanita
Artemisia californica – California Sagebrush
Baccharris puliaris ‘twin peaks’- Coyote Bush
Ceanothus ‘yankee point’ – California Lilac
Encillea farinosa – ‘Brittle Bush
Rhamnus californica – Coffeeberry
Romney coulterii – Matajila Poppy
Salvia clevelandii – Cleveland Sage
While many people make other selections, I feel the plants listed above are the best plants for San Diego slopes. These varieties have proven themselves to grow well on sloped surfaces, control erosion and are all low water selections. Now, as to how to place them on a sloped area… a few tips are to think about how colors contrast with one another and also consider the varied heights of the plants listed. Other elements of design include the plant form or shape, textures and leaf colors.
On a final note, I want to recommend that Native plants are used by themselves as they have very different watering requirements from the other plants. A great resource for using California Native Plants on slopes is Las Pilitas Nursery. Several pages are devoted to using natives on slopes.
Please contact me at Letz Design for more information or greater guidance on the best choices and how to place these plants on your slopes.