As someone once said “ Let’s start from the beginning.” Horticulture deﬁned: the science and art of growing fruits, vegetables, ﬂowers and ornamental plants. Native California plants, more or less, fall under the ﬂower and ornamental plant category, though some are eaten as fruits and vegetables.
What is a Native Plant? My best deﬁnition, an arbitrary one, and it will vary depending upon with whom you’re speaking, is as follows: a native plant is found in or has been living in “the state of California” for the past 10 thousand- 200 million years. Go ahead and create your own deﬁnition, but remember we want to see the plants of “California” survive and be appreciated. As most of you know, we humans are the greatest inﬂuence on their survival or extinction. We could continue to delve into endemic species (ones only found in a distinct or deﬁned location), taxonomy (orderly classiﬁcation of plants or animals with presumed relationships), but we’re here to focus on horticulture.
As a professional landscape contractor, I ﬁnd it is important to consider four factors when selecting plants: soil (structure, texture and fertility), water (requirements and issues), topography (location and slope) and sun (temperature, light). These four factors will have the most impact on whether your plant survives year after year. Other factors will affect a plant’s health (disease, pests, ocean salt spray, human intervention: pollutants, pruning, too much fertilizer), but only after the plant is established.
It is also important to remember that these factors (soil, sun, topography and water) work synergistically: in tandem. Soil: plants have had success for many reasons, but the soil type (structure plus texture plus elemental properties), can be a determining factor whether it lives or dies. Adding amendments only temporarily placates the roots; fooling it for a short time. That is why many natives should be planted without additional fertilizers or amendments. Sun: too much heat for you, as well as for a plant, will cause it to suffer or reduce its full potential. Too little heat or light, the same. The porridge (a.k.a. sunshine (temperature and light)) needs to be just right! Salvia spathacea (Hummingbird Sage) does great beneath tree canopies, as it prefers a shady home. In contrast, manzanitas and Ceonothus spp. thrive in heavy sun exposure environments.
Topography: I deﬁne topography as a place relative to slope, direction (N, S, E, W), wind, sunlight per day and surrounding impediments: buildings, large trees or canyons. One example of this are the oaks seen abundantly on the north hilly slopes northwest of Camp Roberts. The south facing slope receives more heat and higher evaporation rates, making the oak “work harder”each day. Another is Dudleya spp. which love south facing exposure on steep rocky slopes.
Water: it plays a signiﬁcant, if not the greatest, role in a plant’s health. California has it all: rain, lack of rain, fog, snow, ice. Plants succeed because of the conditions water creates. It seems simple, yet the difference of one or two inches of precipitation (climate change) can impact a species dramatically. The impact may dwindle in one population and increase in another.
To wrap up, it comes down to “the right plant for the right place”. It sounds simple enough, but often we do not know a plant’s requirements. Some examples: Where do you place Ribes sanguinium? In a south facing exposure on a rocky soil in the north county? It would probably do better to plant it in a sun / shade and in a sandy loam soil. Arctostaphyllos obispoensis prefers a sunny location, serpentine soil, with limited amounts of water. Juncus patens: shady, clay or sandy soil, wet habitat. Should any landscape on the central coast plant a coastal redwood (Sequoia sempervirens)? The answer is probably NO, due to the fact that it loves water or struggles without it.
For references, consider R. G. Turner’s book Botanica, a guide to over ten-thousand plants used in the horticulture / landscape arena. He lists many California species with details on their requirements. Also, Calscape, a guide to the native plants of California, can be found on our state CNPS website.
All the best in your garden and landscape endeavors!
John Doyle, CNPS Horticulture Chair, San Luis Obispo Chapter