Sarcochilus |
Reprinted from theFebruary
1998 issue of Orchids |
Australia has been granted an enviable measure of attention by Mother Nature. She has bestowed upon that fair land a profusion of fauna and flora that, under scrutiny, can boggle the most orderly mind. Among this treasure of floral gems reside some of the more spectacular members of the Orchidaceae. There are in excess of 105 orchid genera, containing more than 650 species that contribute to the renowned floral wonders of Australia. Among these is the genus Sarcochilus.
Sarcochilus contains some impressive plants that, although not widely cultivated outside of Australia, are excellent subjects for the beginning grower. They are compact plants with a monopodial habit that form dense clumps rather quickly and are floriferous in the extreme. The flowers range from ¼-inch-diameter to nearly two inches in some exceptional clones. There are typically three to 15 colorful flowers per raceme and as many as four racemes per growth. As an added bonus, many flowers are fragrant.
This genus has been in a constant state of revision since its establishment by Robert Brown in 1810. Once, it was thought to contain nearly 200 species with wide distribution throughout most of Asia, the Pacific Rim and the South Seas. Current taxonomic thought embraces only 15 recognized species with distribution confined to Australia, New Guinea and a few Pacific islands.
In Australia, representatives of this genus have staked claim to homesteads throughout an area whose western boundary is the crest of the Great Dividing Range -- the eastern boundary being the Pacific Ocean. The range has a northerly limit near the tip of the Cape York Peninsula and a southerly perimeter that includes most of the north coastal area of Tasmania. Were we to transpose the southerly latitudes to northerly latitudes, we would be talking about a fairly narrow coastal strip that ranges from northern Peru in the south to central Oregon in the north. You can well imagine the scope of climatic variables that would be encountered within that range.
Sarcochilus species are found growing in the cold, damp conditions of the south, and also in the warm and fairly dry conditions of some of the northerly habitats. A little research could produce a species or hybrid to fit almost any growing condition. Four of the Australian Sarcochilus species are lithophytes and 11 are found, in situ, as epiphytes. The lithophytic representatives are most often used in hybridization, because they possess desirable floral characteristics and readily adapt to container culture. The lithophytes are Sarcochilus ceciliae, Sarcochilus fitzgeraldii, Sarcochilus hartmannii and Sarcochilus roseus.
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Dick Doran grew this Sarcochilus hartmanni var. albus 'Geordies', AM/AOS. This species, which is native to Australia, is one of more readily obtainable members of this genus. Photo: © Phil Matt. |
Meeting the Plants' Cultural Needs
Although sarcochilus occupy a wide spectrum of habitats with widely diverse temperature ranges, the locations usually have three things in common: high humidity, exceptional air movement and moderate to low light conditions. They are most commonly found in gullies, ravines and gorges clinging to hosts that allow for frequent dampening of the root system, whether on rock or wood. Providing these cultural conditions will ensure you a successful foray into the cultivation of sarcochilus. Many growers of my acquaintance have had great success growing Sarcochilusfitzgeraldii under their existing benches, although often they find it necessary to bring in a floor fan to add the air movement this species requires.
Temperature, Humidity and Watering Most sarcochilus need minimum temperatures of approximately 40 F but will tolerate a light frost with overhead protection and constant air movement. The plants grow best with maximum temperatures less than 90 F. My shade-house-grown plants are occasionally subjected to short-term light frosts (28 F) and summer temperatures that reach 115 F. Under the later conditions, plants require frequent misting and drenching to prevent dehydration. Lacking pseudobulbs, and thus having no large reservoir for storage of moisture and nutrients, this orchid’s storage facility is its leaves. Careful observation of the condition of the leaves will alert you to the plant needs. For example, shriveled leaves usually indicate under-watering. (Caution: It can also mean root infections or infestations. A visual examination of the root system will assist in making a accurate diagnosis and formulating corrective action.)
Conditions of moderate to high humidity are necessary for optimum growth. I have found that, in most cases, a relative humidity of 40 percent will sustain life and allow for a reasonable growth rate. Plants subjected to humidity in excess of 60 percent grow at a faster rate and produce many more new growths and flowers. As a general rule, sarcochilus need moisture and resent any long periods of dryness. However, that does not mean they need to be kept constantly wet. Maintenance of a moist (not wet) condition at the roots will be rewarded. Be extremely careful not to overwater during the colder months and always avoid standing water in the crown of the plant.
Fertilizing The views among experienced growers concerning the fertilizing of this genus are many and varied. Recommendations range from "do not feed" to "feed heavily all year." My personal experience indicates that a regimen of light feeding when in active growth is extremely beneficial. I recommend that a balanced (20-20-20) water-soluble fertilizer containing micronutrients be applied during this period. The fertilizer should be mixed to approximately one-eighth strength and applied weekly. Further, a monthly drenching of plants with plain water, or a mild magnesium sulfate solution, will assist in precluding an undesirable buildup of fertilizer salts.
Repotting the Plants
All of the lithophytic, and some of the epiphytic, Sarcochilus can be successfully grown in pots. My personal favorites are made of clay. I find that they help prevent excess water from accumulating around the roots, a condition that is detrimental to the health of most potted orchids. Clay pots accomplish this by wicking away residual water. I have obtained the best results with shallow (azalea) pots, bulb pans and saucers drilled to provide drainage.
Almost any potting-mix formula that provides the necessary drainage, air movement throughout the mix and capability of retaining some moisture can be used. I use a mixture of equal parts fairly coarse (1/2- to 3/4-inch) fir bark and rock and have been satisfied with the results. For the rock component, I have used gravel, lava rock and Hydrolyte (expanded shale) with equal success. The lava rock has a slight edge because of its moisture-retentive qualities.
Pests and Diseases
Frequent visual inspection of your plants is necessary to prevent an infestation of scale. At the same time, you can be on the lookout for any snail or slug damage at the earliest possible time. These pests seem to think that sarcochilus was made just for their sustenance. Control is rather easy. A cotton swab dipped in alcohol or a spray with a fine horticultural oil will eliminate scale. Nighttime hand-picking, with flashlight, is my preferred method of slug eradication. Most commercially available baits containing metaldehyde will alleviate, if not eliminate, a slug or snail problem.
Inducing Sarcochilus to Flower
The vast majority of species and hybrids in Sarcochilus are not reluctant nor hesitant to flower. Many instances of these plants flowering in flask have been documented. The odd plant that I encounter that proves to be difficult to flower is usually coaxed into bloom by analyzing that individual plant's position as it releates to its floriferous neighbors. Usually, the plant is excessively shaded and air circulation is blocked by more robust-growing adjacent plants. Relocating the plant to a site offering an increase in light and air flow often solves the problem.
Plants to Try
Of the 15 Australian Sarcochilus species, most lend themselves to easy cultivation. There are a few that are extremely difficult to grow, even for experienced commercial growers.
Three great Sarcochilus for novices --two species and one hybrid -- are discussed here. These plants will flourish in conditions readily available to, or attainable by a beginning grower. Also, an experienced grower wanting to expand his or her horizons would be well served to pick one of these.
Sarcochilus hartmannii This species is one of the best known and most commonly grown, due to its rewarding floral displays and ease of culture. The racemes are approximately 10 inches long carrying from three to 25 flowers that average 11/2 inches in diameter. It is not unusual for a mature plant to display hundreds of flowers. They will grow well mixed in with cattleyas or laelias. Shade from 60 to 80 percent, air circulation, a coarse mix and a shallow clay container all contribute to success. Be careful not to overwater. Keeping the mix just moist is the proper condition.
Sarcochilus fitzgeraldii Although more demanding than Sarco. hartmannii, this orchid will reward the attentive grower with some of the most colorful flowers to be found in the genus. Racemes normally carry from three to 15 delicately scented flowers that often contain a high percentage of red markings on a white background. Some desirable clones display solid red, maroon, crimson or raspberry floral segments. The common name for this plant is the ravine orchid, which is a clue to the cultural requirements of this orchid. It demands constant air move ment, 80 to 90 percent humidity and moist conditions. A coarse, moisture-retentive potting mix in a shallow clay pot, or saucer, is recommended. Although an occasional drying out is not life threatening, avoid letting the mix stay completely dry for more than a couple of days. Some phalaenopsis fanciers have found that this plant grows well on the shadiest areas of their benches.
Sarcochilus xfitzhart (hartmannii x fitzgeraldii) If a fool-proof Sarcochilus exists, it must be Sarcochilus xfitzhart. I know of none easier to grow. This plant is a natural hybrid seldom found in situ. I would hope that all plants available today are artificially made. They are floriferous in the extreme and bear flowers with shapes midway between the two parents. These plants exhibit hybrid vigor and will grow into specimens fairly rapidly. I have found that they are extremely adaptable and will grow well under the conditions stipulated for either parent and anywhere in between. I have grown this plant successfully under both conditions recommended for cattleyas and phalaenopsis. Remember, lots of air movement coupled with cool (not cold) and moist (not wet) conditions give optimum results.
Sarcochilus deserves to be grown more widely and should gain greater attention as hobbyists discover these Australian gems. []
George F. Kenner Sr. is the owner of Kenner & Sons. · 10919 Explorer Road, La Mesa, California 91941.