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Why the Conejo Valley Botanic Garden is a magic mountain you must visit

Posted on March 19, 2021 by Conejo Valley

By JOSHUA SISKIN | [email protected] |
PUBLISHED: March 6, 2021 at 8:29 a.m. | UPDATED: March 19, 2021 at 5:57 p.m.

The Conejo Valley Botanic Garden, a hillside and hilltop horticultural haven, is a community asset highly worth a visit. Rising above the surrounding city of Thousand Oaks, the soil on this modest-sized magic mountain has never been amended, and the plants that thrive there have never been fertilized.

Three factors have contributed to the plants’ well-being. First, they are constantly mulched with tree trimmers’ wood chips. Second, the sloping terrain for the hillside plants and the granitic soil for the hilltop plants ensure that water drains completely away from roots – a critical factor since the least bit of standing water would be fatal to many of the dry climate species on display. Third, the devotion of volunteers to maintenance of the collections, which include plants from the five Mediterranean climate zones around the globe — California, Chile, the Mediterranean Basin, South Africa, and Australia — as well as a butterfly garden, a tranquility garden, a rare fruit orchard, a butterfly garden, an herb garden, a salvia garden, and a fern.

The Conejo Valley Botanic Garden (CVBG) is open seven days a week from 8 a.m. to 6:45 p.m. It is located at 400 West Gainsborough Road, Thousand Oaks. The Kids’ Adventure Garden is open from 11 a.m to 3 p.m. on Sundays. A plant sale is held from 9 a.m. to 12 noon each Wednesday. Admission is free. Dogs on leashes are allowed. Masks are required.

Speaking of the power of mulch, 10 years ago when I visited CVBG there was a vast expanse of weedy black mustard (Brassica nigra) that I never would have dreamed could be redeemed. Yet here we are a decade later and it has been transformed into a thick blanket of black, white, and purple sages. I asked Steve Davis, a landscape architect who helped design the initial garden, how this was done and he cited mulch and hand pulling as the two strategies employed for elimination of the mustard.

As for the beneficial effect of sloping terrain on the growth of the plants at CVBG, I bring Anisodontea x hypomandarum as proof. I have never seen this plant live for more than a few years in anyone’s garden. Even if it gets nothing but winter rain, it is susceptible to root rot where soil is not perfectly drained. But here, in the South African section, it has reached enormous size and is the picture of health after many years in the ground.

Another example of the power of this location is an Australian peppermint willow (Agonis flexuosa). I was astonished to learn that this glorious tree was planted only 27 years ago from a 15-gallon container. Its girth and muscular limbs make it look like it has been there for a century at least. Its symmetry is matched by a nearby specimen of the Queensland bottle tree (Brachychiton rupestris).

Alstroemeria highlights the Chilean section that has only recently been added to the Conejo Valley Botanic Garden. The Alstroemerias we see in our gardens are hybrids between winter-growing Chilean species and summer-growing Brazilian species. These hybrids are virtually evergreen, experiencing only a brief winter dormancy period. Alstroemerias can survive drought and neglect due to their sustaining underground rhizomes. Rich in starch, these rhizomes are part of the diet of the indigenous peoples who live within the Alstroemeria’s habitat. Angel’s trumpet (Brugmansia) is another Chilean selection.

The animal which gives Conejo (meaning “rabbit” in Spanish) Valley its name is the only major pest to contend with at CVBG. Chicken wire encircles plants known as rabbit munchables.

Generally speaking, plants with strong fragrances or flavors, including rosemary and pungent sage species, are not eaten by rabbits. Lomandra, an Australian grass with chartreuse and lime green foliage, is also immune to rabbit ravages. Alstroemeria contains a toxic chemical that causes some animals to stay away while others become ill from its consumption. Not taking any chances, CVBG’s recently planted Alstroemerias are surrounded by chicken wire.

One of the most eye-catching species from South Africa is Euphorbia esculenta. The plant is currently at peak bloom and its flowers at a distance look like daisies. I learned that it is easy to grow and I only wonder why we don’t see it more often. Davis told me that many of the selections on display have been planted with the homeowner in mind. The plants are not only meant to be looked at but are also selections that, not typically seen, will serve admirably as durable choices for the average garden.

To this end, several infrequently seen rosemary cultivars have been planted. An example is ‘Tuscan Blue,’ whose stems shoot up in all directions, producing a pyrotechnic effect. The stems are studded with royal blue flowers. It would make a wonderful complement to ‘Torch Glow’ bougainvillea, a cultivar whose magenta bracts are festooned along shoots that grow out in all directions in a manner that mimics the grown habit of ‘Tuscan Blue.’

Two germanders (Teucrium spp.) are looking brilliant at the present moment at CVBG. Creeping germander (Teucrium cossonii), not exceeding six inches in height, spreads out to three feet, is cold hardy and drought tolerant. Lavender to purple flowers are seen throughout spring and summer but even in its present flowerless state it is something to behold due to its small, daintily scalloped, sea-green foliage. Bush germander (Teucrium fruticans) is a shrub that can grow up to five feet tall and wide. Blue flowers contrast nicely with silvery-gray foliage.

No selection for dry shade is more sensible in our part of the world than hummingbird sage (Salvia spathacea). It grows under oak trees and can go the entire summer without water although it will stay greener in the hottest weather if occasionally soaked. Thick upright magenta flower clusters are accompanied by foliage that emits a pleasant scent when crushed. Hummingbird sage is distinguished from other native sages by its rhizomes, the same structures that allow bearded iris and agapanthus to spread. You can plant hummingbird sage in the shadiest part of your garden and, as long as the soil is consistently mulched, it will just grow and grow and grow.

I was met at the entrance to CVBG by Beverly Brune who, together with Robin Pakorski, has been responsible for fundraising for development of the 33-acre site. I was introduced to Carl Zhu who coordinated a drone flight over the area as a project for local students. The drone photographed tree canopies to evaluate them for carbon dioxide uptake. Trees absorb carbon dioxide through their leaves for photosynthesis, a process that on a large scale reduces air temperatures.

Zhu is responsible for the aviary filled with finches in the Kids’ Adventure Garden. His wonderful photographs are to be found on the ConejoValleyBotanicGarden.com website, which was designed by his daughter. Thanks to Steve Davis for guiding me through the garden and to Jim Allyn for inviting me to visit.

Tip of the Week: If you are pondering low-maintenance formal or informal hedge possibilities, consider the California native lemonade berry (Rhus integrifolia) before making your final decision. Lemonade berry has undulating, leathery sea-green foliage and dense clusters of pink and white flowers followed by utilitarian fruit. To be precise, the fruit should not be eaten whole but can be masticated or sucked for its juice, after which its pulp should be discarded.

Soaking the fruit in cold water also makes a tart and refreshing summer drink. In fact, all plant parts are edible and/or medicinal, as attested to by the many Native American tribes who relied on it for a variety of uses. The only caveat is to experiment with this plant in small quantities for its edible and curative properties since some people experience allergic reactions to it.

Lemonade berry is in the sumac family, with cousins such as poison ivy, poison oak, cashew, pistachio, mango and Brazilian and California pepper trees, all of which are distinguished by turpentine-scented sap. Although it can grow to a height of 10 feet, with an equal or greater girth, lemonade berry may be kept to half that size with occasional pruning. Some people have a dermatitic reaction to contact with its sap so, to be safe, wear gloves while pruning it.

Please send questions, comments, and photos to [email protected]

Hero image – Hummingbird sage (Salvia spathacea). (Photo by Joshua Siskin)

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