In last week’s column, I mentioned four horticultural marvels:  a magnificent Torrey pine in the Mildred Mathias Garden at UCLA, a 700 year old coast live oak at Orcutt Ranch in West Hills, a grove of king palms at the Virginia Robinson Gardens in Beverly Hills, and a long hedge of poinsettias in Camarillo.  Here are numbers 5, 6, and 7 —  completing the list of seven wonders of our local plant world.

Number 5 of 7 Botanical Wonders of Los Angeles

5.  The Huntington Desert Garden in San Marino is not only unique to Southern California.  It is considered by some to be the most outstanding garden of its kind in the world.  There are not enough superlatives in the dictionary to describe the treasures found here.  The garden consists of 2,000 cactus and succulent species, while the Desert Conservatory or greenhouse, at the garden’s upper end, is home to an additional 3,000.  Take note that while the garden may be visited every day of the week (except when closed on Tuesday) from 10 a.m. to 5 p.m., the conservatory is open on Saturdays only, from 10:30 a.m. – 4:30 p.m.  You can visit the gardens at no charge on the first Thursday of each month but, in order to do so, you must order tickets in advance, online, through the website at huntington.org.

Henry Huntington was in the railroad business and this made it possible for him to develop 10 acres into the desert garden that bears his name.  Huntington had an extension to his railroad built right up to his property!  This made it possible for him  to bring in vast quantities of special soil and rock that a desert garden foundation requires.  It was the early years of the twentieth century.  At that time, there were no restrictions on digging up plants wherever you found them and so, in 1908, three railroad cars full of plants plucked from the Arizona desert were sent directly to Huntington’s new garden site.

There are two principle take home lessons from the Huntington Desert garden.  The first is that clustering or massing together many individuals of the same species is a sure way of creating a pleasurable and memorable garden experience.  The second is that a sloping terrain makes an important contribution to the excellent soil and air drainage that are essential for growing desert plants.  Cactuses and succulents abhor standing water around their roots and therefore demand fast draining soil, enhanced by sloping topography.  Many of these plants are also sensitive to cold and since cold air, like water, rolls downhill, planting them on a slope will diminish the possibility of suffering serious dieback in a frost.

Number 6 of 7 Botanical Wonders of Los Angeles

6.  The azalea maze in the Getty Center garden in Brentwood is a quintessential horticultural extravaganza.  Otto von Bismarck, the powerful diplomatic deal maker of 19th century Europe, is famously quoted as saying that politics is “the art of the possible.”  Horticulture in its ultimate expression, by contrast,  could be defined as the art of the impossible or, to be precise, the seemingly impossible.  For instance, growing oranges in Alaska, you might think, would be impossible.  However, as long as you have a heated, well-lit greenhouse, you will have no problem growing oranges anywhere, even in the Arctic Circle.

Growing azaleas in Los Angeles, while perhaps not as outrageous as growing oranges in Alaska, is definitely going against the grain.  The evergreen azaleas in Los Angeles gardens are hybrids produced from species indigenous to East Asia, a part of the world whose wet climate and acidic soil conditions offer a sharp contrast to the dry Mediterrranean climate and alkaline soil found in Southern California.  The origins of the azaleas that are found in local nurseries and decorate our gardens can be traced primarily to Japan and, to a lesser extent, to southeast China, Korea, the Philippines, and Taiwan.  Locally, azaleas are not noted for their longevity yet there are individual specimens in Japan that are several hundred years old and a few of them have trunks that measure more than one foot in diameter.  Thus, if you could create the perfect growing conditions for azaleas, whether in your backyard or in containers on your patio, they could conceivably become family heirlooms.

The key to growing azaleas is soil conditioning.  Some people excavate a considerable volume of soil and replace it with pure peat moss, whose acidity matches the pH of the native Asian soil in which azaleas grow.  Others mix sand or top soil until it comprises up to 50% of a soil mix whose other ingredient is peat moss.  Maintaining a layer of humus or aged compost around azaleas at all times is also a wise practice which will curb, if not eliminate, the need for fertilization.  Under such conditions, water only when soil under the mulch is dry at a two inch depth.  Pruning of azaleas is not required except for training purposes or for keeping them at a desired height.

Number 7 of 7 Botanical Wonders of Los Angeles

7.  The transition from the Getty azalea maze to the Descanso Garden camellia forest in La Canada is rather smooth since azalea and camellia share the same East Asian habitat and have similar growing requirements.  In 1874, there was a fire on the future site of the Descanso camellia forest.  As a result of that fire, acorns germinated and slowly grew into the coast live oak canopy of 1200 trees under which the camellia forest was planted — mostly in the 1930’s and 40’s, but upgraded ever since.

Talk about ultimate and extreme horticulture!  Here you have a grove of native oaks that, even in a drought, seldom if ever require irrigation, and yet they are underplanted with camellias that demand, according to the Sunset Western Garden Book, “moderate to regular water.” And this is no ordinary camellia collection, either, but the largest in the world, numbering 654 varieties and 12,000 plants  Perhaps it’s the soil acidifying effect of the ever present oak leaf mulch that makes this all possible.

The Japanese camellia (Camellia japonica) bloom period is arriving now and it will peak over the next two months or so. When March arrives, make sure to visit Descanso’s impressive lilac collection, too, and, a month later, enjoy the first bloom of the several thousand roses in the International Rosarium.  Descanso Gardens is open every day of the year, except tomorrow, from 9 a.m. to 5 p.m.

I would like to publicize other local plant wonders so if you have any to share, please let me know about them.  Sending along a photo or two of the plant wonder(s) in question would be greatly appreciated.

Honorable Mentions to the 7 Botanical Wonders of Los Angeles

Tip of the Week  For plant wonder honorable mentions, I would draw your attention to the jacarandas on Stansbury Avenue a couple of blocks south of Ventura Boulevard in Sherman Oaks,  to the sycamore trees on Cantura Street, one block south of Ventura in Studio City, and to the sequoia trees adjacent to the Franklin Canyon Reservoir north of Beverly Hill.  (Take an extra moment to make full stops at Franklin Canyon stop signs, which are camera equipped.  Not making a full stop will generate a $175 ticket.)

      Last but not least, I would be remiss not to include the Theodore Payne Foundation native plant nursery, a horticultural wonder beyond compare, in this discussion.  Nowhere will you find such an immaculate display of unblemished and vibrant containerized plants. Significantly, there is a placard next to each species describing its growth habit and cultural requirements in great detail.  There is no other local nursery that approaches this one, whether as an aesthetic or as a learning experience.  It is located at 10459 Tuxford Street in Sun Valley and is open Tuesday to Saturday from 8:30 a.m. to 4:30 p.m.