San Diego Botanic Garden presents Gardenscapes

By Chris Garcia

San Diego Botanic Garden’s (SDBG) California Gardenscape area is divided into several ecological zones similar to those topographical areas found in Southern California.

Former SDBG Chris Garcia, who redesigned this area in San Diego Botanic Garden, describes the areas found within this unique garden scape; how he created and developed these unique areas; and provides some helpful tips for home gardeners desiring to replicate one or more of these spaces in their own yards:

Wildflower Meadow

Landscape Typology: Grassland/ Wildflower Plains

Natural Places in San Diego: Laguna Mountain State Park, Ramona Grasslands Preserve

Description: A Wildflower Meadow was cleared in a barren area along the Quail Gardens Drive fence line. The soil here is sandy and hydrophobic, making it especially difficult to establish new plants. Thus, a 15×25-foot area was raked around a large existing tree stump and amended with reclaimed potting soil to promote infiltration. The perimeter of the space was mounded with mulch to create a weed buffer and planted with perennial grasses such as deer grass (Muhlenbergia rigens) and canyon prince wild rye (Leymus condensatus ‘Canyon Prince’) to define the circular space.

Wildflowers in this area include larger annuals such as Sunflower (Helianthus annuus), Giant Phacelia (Phacelia grandiflora) and Hooker’s Primrose (Oenothera hookeri) as well as smaller annuals such as lupine (lupinus sp.), poppies (Eschscholzia californica) and baby blue eyes (Nemophila menziesii). The wildflowers were grown using a combination propagated plantings and seeding. Larger annuals such as Sunflower, Giant Phacelia, and Hooker’s Primrose were propagated from 2-inch flats for better mortality and prevention of pest damage. Smaller annuals such as lupine, poppies and baby blue eyes were seeded in the foreground with high success. The intent was to create a circle of color at the garden entrance to catch a guests’ attention from the upslope path overlooking it.

Helpful Tips: Timing and soil are key factors in developing a wildflower meadow. The first round of seeding should occur just before or after the first fall rains. The meadow can be lightly reseeded every 3-4 weeks through the rainy season to create waves of color over a longer period into June. The earlier the fall seeding, the better for getting plants established for larger blooms and a longer season. Make sure to include late season perennials such as fuchsia (Epilobium sp.), goldenrod (Solidago californica) and native milkweed (Asclepias sp.) for summer interest.

Montane Rock Garden

Landscape Typology: Mountains above 5,000 feet

Natural Places in San Diego: Palomar Mountain State Park, Garnet Peak, Cuyamaca Rancho State Park

Description: Under a rustic Catalina Ironwood (Lyonothamnus floribundus), a thicket of Black Sage and Coast Encelia was cleared to form a rock berm. Soil was added to increase the slope and elevation and boulders used to terrace the mound and create planting niches. A circular birdbath was relocated near the high point of the mound, symbolic of a mountain lake. Plants that are adapted to montain rock outcroppings were planted such as red monkeyflower (Mimulus puniceus), foothill penstemon (Penstemon heterophyllus) and yellow lupine (Lupinus densiflorus aureus).  This created a red, purple and yellow flash of color I termed the ‘disco ball’ planting. These plants love to get their root under the cool, moist undersides of stones. The moist low area behind the mound was planted with annuals to create a green and colorful backdrop. Redwood Gorilla Hair Mulch was added around the boulders to prevent erosion and maintain moisture.

Helpful Tips: Redwood mulch is the best bedding for natives because it breaks down slowly and adds negligible organic matter to the soil. Most natives thrive in arid, fungal-based ecologies with inorganic, mineral soils so refrain from amending the soil. Boulders are fabulous place-making elements that create niches for plants that require excellent drainage.

Desert Garden

Landscape Typology: Low and high desert ecosystem

Natural Places in San Diego: Anza-Borrego Desert State Park

Description: Agaves were the main plantings in a small inconspicuous area with a sign labeled “Desert Garden” before the redesign.  A small stone wall and orange pea gravel dubiously alluded to a desert landscape. The area was doubled in size by removing sage and sagebrush and relocating ¾-inch gravel from the foothill area. Boulders were used to create a gradual terraced slope. Perennials such as desert mallow (Sphaeralcea ambigua), desert lavender (Hyptis emoryi) and apricot mallow (Abutilon palmeri) were planted to contrast and balance the spiky specimen agaves and cacti with soft foliaged perennials. The area was seeded with colorful desert annuals, including Mojave prickly poppy (Argemone corymbosa), desert marigold (Baileya multiradiata) and desert dandelion (Malacothrix glabrata).

Helpful Tips: A composition of different-sized rocks and decomposed granite is helpful in creating a perceived desert landscape. Darker boulders conduct and reradiate heat while lighter stones reflect light and create an albedo effect, conditions typical of the desert floor. In contrast to other native ecologies which like water during the cool season, desert plants benefit from infrequent year-round watering, with warm weather misting during the summer to mimic the humidity of afternoon thunderstorms. A bounty of uniquely adapted plants grow in this community, so it is easy to create striking contrasts between such specimens as Ocotillo (Fouquieria splendens), desert agave (Agave desertii), brittlebrush (Encelia farinosa), and sand verbena (Abronia villosa).

Coastal Dune Garden

Landscape Typology: Coastal Strand

Natural Places in San Diego: Border Field State Park, Cabrillo National Monument, Torrey Pines State Park

Description: Sinuous sand mounds replaced thickets of black sage and sagebrush to create an S-shaped wave creating an overall effect analogous to a weathered coastal fissure. The crests and depressions of the mounds create niches for creeping groundcovers characteristic of the immediate coast. Plants such as red sand verbena (Abronia maritima), beach primrose (Camissonia cheiranthifolia), and silver beach bur (Ambrosia chamissonis) naturally move and flow with transitory wind-blown and rain-weathered landforms. The long shadows of the morning and evening sun accentuate the mounds while coastal annuals such as miniature poppy (Eschscholzia caespitosa) brighten the landscape and glimmer in the sunshine. Red buckwheats (Eriogonum grande rubescens) and coastal gumplants (Grindelia stricta),  extend the show well into summer. Over time, the mounds will be carpeted in rolling groundcovers, contrasting each mound by foliage texture and color.

Helpful Tips: Every coastal garden should have “sand dunes!” Mimic salt spray with frequent light misting during cool summer mornings and use low volume overhead sprinklers to minimize runoff. Erosion is less of a concern as the groundcovers intermingle and the beach party begins!

Bioswale

Landscape Typology: Vernal Pool

Natural Places in San Diego: Miramar plateau near State Route 163, Kearny Mesa, Otay Mesa

Description: A central open area surrounded by large shrubs was chosen to carve-out an ovate bioswale. The decomposed granite path directly above the area produced storm runoff and erosion. A swale was added along this path to drain into the newly formed bioswale, where it quickly infiltrates the soil. The basin is filled with a 2-inch layer of mulch to sponge the moisture. Wire grass (Juncus sp.), California Sea Lavander (Limonium californicum) and spice bush (Calycanthus occidentalis) were planted for their tolerance of both dry and wet seasonal cycles.

Helpful Tips: This is the perfect landform to place under a rainspout or at a low spot in the landscape. Make sure to select natives that are adapted to both wet and dry periods such as San Diego Sedge (Carex spissa) and False Indigo Bush (Amorpha fruticosa).

Woodland Garden

Landscape Typology: Oak woodlands, Canyons

Places in San Diego: Mission Trails Regional Park, Volcan Mountain Wilderness Preserve

Description: An area near the grape arbor, shaded by a large lemonade berry (Rhus integrifolia), catalina cherry (Prunus ilicifolia), and black walnut (Juglans californica) was chosen for dry, shade-loving woodland natives. A dry streambed, previously constructed by volunteers added a place-making element. Plants that thrive in dry shade such as coral bells (Heuchera sp.), bush anemone (Carpenteria californica), golden currant (Ribes aureus), coffeeberry (Rhamnus californica) and douglas iris (Iris douglasiana) were added for color and foliage. A woodland garden is an important transition landscape between drier chaparral and riparian ecosystems. Many of the plants correspond to mycorrhizal fungi in the soil that transport moisture and nutrients from wetter to drier habitats.

Helpful Tips: Allow leaf litter to act as mulch and encourage mycorrhizal soil development. Especially important in a woodland garden are the shadows and quality of shade. Prune trees and shrubs to frame views and allow filtered sunlight. Choose plants for foliage and texture to create year-round interest.

Blue-Grey Garden

Landscape Typology: Garden planting for contrast and texture, moon garden

Places in San Diego: San Diego Botanic Garden

Description: This was a pre-existing garden that was expanded during the redesign and includes silvery foliaged plants that you might find in a moon garden. An abundance of natives have blue to silvery foliage and are adapted to reflect sunlight and reduce evapotranspiration. Excellent specimen choices for blue-grey foliage include: Canyon Prince Wild Rye Grass (Leymus condensatus), purple sage (Salvia leucophylla), Catalina Fuchsia (Epilobium ‘Catalina’) and Catalina Silverlace (Eriophyllum nevinii). A large rhinoceros-shaped stump was added as a place-making sculptural element. The blue jays are especially fond of sitting on this in our Garden, adding to the blue-grey theme.

Helpful Tips: Contrasting foliage is especially important to create year-round interest in a native garden. For contrast, use plants with silvery or light green foliage against a background of darker green evergreen shrubs such as wild lilac (Ceanothus sp.), lemonade berry (Rhus integrifolia) or chamise (Adenostoma fasciculatum).

Foothill Garden

Landscape Typology: Foothills between 1,000 to 3,000 feet in elevation

Places in San Diego: Volcan Mountain Wilderness Preserve

Description: This was a crowded, undefined area with three beautiful Western Redbuds prior to the redesign. Toyon (Heteromeles arbutifolia), black sage (Salvia mellifera) and laurel sumac (Malosma laurina) were cleared to open-up and display the multi-branched structure of the redbuds. Foothill plants with pink to purple blooms such as foothill penstemon (Penstemon heterophyllus), hummingbird sage (Salvia spathacea) and wooly blue curls (Trichostema lanatum) were planted to correspond with the pink blooms of the deciduous redbuds.

Helpful Tips: The oak foothills are the iconic image of the California landscape. Contrast soft grasses such as purple needle grass (Nassella pulchra) with picturesque shrubs such as manzanita (Arctostaphylos sp.). Correspond a synchronistic bloom period of similar colors between a diversity of plants as a temporal place-making element. Deciduous trees and shrubs add seasonal interest and structure to a native landscape.

Overall, the ecologic zones in California Gardenscapes create a deeper sense of place with landforms corresponding to specific plant communities. The series of gardens facilitates a cadence around the path circuit, encouraging guests to slow-down, stop often and take-in each landscape vignette. This invites guests to consider not only individual plants but an entire drought-tolerant native landscape redesign of their own yard. But perhaps the greatest result is what cannot be seen; the connection one feels as a part of the natural ecology when constructing and caring for a native garden, so that the distinction between “natural” and “garden-like” becomes quite inconsequential.

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