The Cattleya Alliance is part of the subfamily Epidendroideae, the largest subfamily in the Orchidaceae, and contains the genera Brassavola, Broughtonia, Cattleya, Encyclia, Guarianthe, Laelia, Myrmecophila, Rhyncholaelia, Schomburgkia and Sophronitis with > 350 recognized species. They are found in the New World and are mostly tropical epiphytes. The Cattleya alliance is horticulturally important and has been extensively hybridized.
Cattleya Alliance plants are easy to grow, especially outdoors in San Diego. Most species and hybrids prefer intermediate temperatures, but there are a few warm and very few cool growers. Thus, it is important to know the climatic conditions of the original habitat and adapt the cultural conditions if necessary.
Tips to grow Cattleya Alliance plants:
- Cattleyas need bright, indirect light – avoid direct sunlight during the hot parts of the day. Be careful when moving plants, like outdoors in spring – the thick fleshy leaves are actually surprisingly susceptible to sunburn – slowly acclimate the plants!
- Cattleyas prefer intermediate temperatures, with daytime temperatures between 20-35°C (68-95°F) and a nighttime drop of at least 5°C (9°F). They can tolerate brief periods of light frost. Keep the plants dry during cold weather!
- Cattleyas grow best at 50-70% humidity but are somewhat tolerant of lower humidity and can cope with Santa Ana conditions relatively well. Water once or twice a week in summer and less in winter. Watch the pseudobulbs : shriveling is a sign of under- or overwatering (check the root system for damage: wiggle the plant in the pot!)
- Cattleyas are heavy feeders. During growth, fertilize with every watering with a balanced fertilizer recommended for orchids, like the MSU fertilizer. Flush out excess salts with large quantities of water. Reverse osmosis (RO) water is recommended.
The Cymbidium Alliance is part of the subfamily Higher Epidendroideae, tribe Cymbidieae, containing the genera Ansellia, Cymbidium and Grammatophyllum. The genus Cymbidium consists of ~80 species that have a wide geographic distribution in Asia, ranging from Sri Lanka, India, Nepal, Bhutan through Myanmar, Thailand, Vietnam, Malaysia, China and Indonesia all the way to Taiwan, Korea, Japan, the Philippine islands and Australia. They can grow as epiphytes, lithophytes or terrestrial. Many species do well outdoors in San Diego, but the more widely available hybrids are an even better choice.
The general orchid care instructions only need to be slightly modified for Cymbidium plants – outdoor culture is recommended for San Diego.
Tips for growing Cymbidiums:
- Cymbidiums need bright light but do not tolerate direct sunlight, especially during the hottest part of the day. They grow best in 50-70% shade or in the partial shade of a tree.
- Cymbidiums prefer intermediate temperatures, with daytime temperatures between 20-35°C (68-95°F) and a nighttime drop of 5°C (9°F). They can tolerate brief periods of light frost, but should be kept dry during cold weather.
- Cymbidiums are tolerant of low humidity and can tolerate Santa Ana conditions relatively well. Ideally, humidity should be kept around 50-60%.
- Watering frequency depends on a number of factors, but Cymbidiums generally need less water than other orchids. In summer, water every other week. In winter, water once a month or less, and provide some cover from the rain.”
- Cymbidiums are heavy feeders and need regular fertilization during growth. Flush out excess salts with large quantities of water. Tap water is fine for Cymbidiums, but reverse osmosis water is still recommended.
The genus Dendrobium is part of the subfamily Epidendroideae, although the exact taxonomic placement is still in debate. Dendrobium is a very large genus with over 1800 species and a wide distribution in East, Southeast and South Asia, ranging from India all the way to some Pacific Islands. Not surprising given the huge distribution range, Dendrobiums have adapted to very diverse habitats ranging from hot and humid lowland tropical rainforests to cool highland cloud forests with more or less constant rainfall to habitats with prolonged dry periods and sometimes cooler seasonal temperatures like the Himalayan mountains and even the Australian semi-deserts with a very dry climate. This must be taken into account when growing a particular Dendrobium species or hybrid. Species from Australia, like Dendrobium speciosum, do particularly well outdoors in San Diego (see out Outdoor culture section). Dendrobiums are popular with hobbyists due to their abundant, beautiful and often very long lasting flowers. The flowers of Dendrobium cuthbertsonii hold the record and last a reported 10 months each!
Tips to grow Dendrobiums:
- They generally require bright, but indirect light. However, some species from cloud forests prefer lower light levels, while others, like most Australian species, require high light levels and can tolerate some direct sun after acclimatization. It is important to research the specific light requirements of the Dendrobium species or hybrid that you are growing.
- Dendrobium orchids also have a wide range of temperature requirements. Some species from lower elevations require warm temperatures and suffer on slightly colder winter nights even in a greenhouse, while others from higher elevations prefer cooler temperatures and can only be grown outdoors in coastal areas and in a greenhouse with provision for cooling. It is important to research the specific temperature requirements of the Dendrobium species or hybrid that you are growing.
- Dendrobiums prefer high humidity (50% minimum, 75% ideally). However, Australian Dendrobiums are more tolerant of lower humidity.
- All Dendrobiums are sensitive to sitting in water-logged medium for long periods of time, especially in the cooler winter months. It is important to water Dendrobiums regularly, but allow the potting mix to dry out slightly between waterings.
- Fertilize Dendrobiums with every watering during the growing season so they can produce big and strong pseudobulbs and flower well. Use a balanced fertilizer designed for orchids such as the MSU fertilizer – follow the recommendations on the label – dilute in RO instead of tap water to avoid salt buildup in the root zone.
Lady slipper orchids form a small subfamily, Cypripedioideae, with only 6 genera and about 160 species. They are mostly terrestrial orchids with slipper-shaped pouches (which are modified labella) that trap insects and force them to pollinate the flower.
The horticulturally important genera are Paphiopedilum and, to a lesser extent, Phragmipedium. These orchids are not as easy to cultivate as other orchids and require some cultural adjustment relative to epiphytic orchids, so they are not recommended for beginners.
Tips for growing Paphiopedilum:
- Lady slipper orchids prefer indirect light and do not tolerate direct sunlight.
- They prefer high humidity, try to provide a shady, moist location to grow them.
- The temperature requirements vary depending on the species. Most Paphiopedilum and Phragmipedium species do well outdoors in San Diego in the coastal areas during the summer months. Some species need warmer conditions and must be moved indoors in the winter.
- Lady slipper orchids prefer high humidity, try to provide a shady, moist location to grow them.
- Water them regularly, but allow the potting mix to dry out slightly between waterings. Use a slightly finer potting mix and deeper pots to prevent the roots from drying out too fast when growing them alongside epiphytic orchids.
- Fertilize lady slipper orchids with every watering during the growing season. Use RO water to avoid salt buildup in the root zone.
The Oncidium Alliance is a large and diverse group of orchids with over 1,000 species. They are found in tropical America and include many horticulturally important genera, such as Brassia, Miltonia, Odontoglossum and Oncidium (incl. Tolumnia, now Equitant Oncidiums again) as well as others of interest to the hobbyists (some formerly in the genus Oncidium but now split off) such as Cochlioda (now Oncidium), Comparettia, Gomesa, Miltoniopsis, Psychopsis, Rossioglossum, Trichocentrum and Trichopilia.
Oncidiums have a wide range of cultural requirements, depending on their natural habitat. Some species, such as those from high-elevation cloud forests, require cool temperatures and high humidity. Others, such as those from low-elevation rainforests, prefer warmer temperatures and constant, but more moderate humidity. Others yet, come from habitats with long dry seasons or other types of seasonal variation.
Tips for growing Oncidiums:
- Leaf thickness is a general indicator for light requirements: think leaves plants generally like less bright light and no direct sunlight, light tolerance increases with leaf thickness, direct sunlight during the hot parts of the days should still be avoided.
- The temperature requirements vary depending on the species as mentioned above. Many species do well outdoors in San Diego year-round, some only in the coastal areas. Others can only be grown outdoors in the summer months and must be moved indoors or a greenhouse in the winter (typically mid-November to mid-March in San Diego).
- Oncidiums prefer high humidity (50% minimum, 75% are ideal). Insufficient humidity can lead to accordion leaves in thin-leafed plants and/or brown leaf tips (thin and thick leaved plants).
- Fertilize oncidiums with every watering during the growing season with a balanced fetilizer designed for orchids such as the MSU fertilizer – follow the recommendations on the label. Use RO instead of tap water to avoid salt buildup in the root zone.
Luckily hybrids tend to be more adaptable and can be grown under a wider range of conditions and are therefore recommended for beginners.
Below are links to AOS culture sheets which give more detailed information. (more specific cultural information).
The genus Phalaenopsis has about 70 species which can be found in tropical Asia from India through Indochina to southern China,Taiwan, Malaysia, Indonesia to New Guinea and the Philippines and all the way to the Northern tip of Australia with the greatest diversity found in Indonesia and the Philippines. They are monopodial and typically grow as epiphytes, and less common, as lithophytes. The first species of genus was formally described by Carl Ludwig Blume in 1825, who named it Phalaenopsis from the Greek words “phalaina” (moth) and “opsis” (appearance).
Moth orchids, as Phalaenopsis are commonly called, are the most readily and inexpensively available type of orchid and thus the most popular type grown indoors. This was possible because of extensive hybridization that not only produced new color forms and patterns but also selected for fast and robustly growing plants that allow mass production on a vast commercial scale. The new mass-produced hybrids are relatively easy to care for and produce beautiful, long-lasting flowers in a wide variety of colors and patterns.
Tips for growing Phalaenopsis:
- No ice cubes on the plants! See proper watering technique below.
- Provide them with medium bright light (windowsill or under a skylight is perfect), avoid direct sunlight.
- They prefer moderately warm temperatures, between (16°C, 60°F night minimum, 30°C, 85°F day maximum) and do fine with indoor temperatures that are comfortable to humans.
- They can be grown outdoors in the summer months, but must be moved indoors to a protected environment in the winter (Mid-November to Mid-March in San Diego).
- To increase local humidity, place the plant on a tray filled with pebbles and water (above water line – not in the water).
- Be careful not to overwater phalaenopsis, as this can lead to root rot, the most common reason for failure. Small pots (2”) in sphagnum need water about every other week, while larger pots (4”) need it once a month. For a few plants inside the home: Submerse the entire pot inside the decorative pot and let soak for 5-10 minutes then completely drain the water.
- Fertilize Phalaenopsis at every watering with a balanced fertilizer such as the MSU fertilizer for orchids at the recommended strength. Ideally water low in TDS (total dissolved solids), like RO water or rainwater should be used. Water with plenty of water to flush out accumulating salts.
Following this advice, Phalaenopsis orchids can thrive for many years and rebloom – prerequisite for this is a healthy root system and strong new growth (new leaves).
Vanda are now part of the subfamily Epidendroideae in the tribe Vandeae as their own alliance. Several formerly distinct genera were lumped into Vanda, such as Neofinetia and Euanthe, while the terete leaved Vanda were into their own genus (now Papilionanthe).
Vanda orchids are beautiful but challenging to grow, especially in dryer climates. They require bright light and high humidity, thus frequent misting. Vandas are not recommended for beginners.
Tips for growing Vandas:
- Grow Vandas in bare baskets – no or only very coarse medium – or mounted onto a durable substrate.
- Avoid potting Vandas, as their roots do not tolerate extended periods of wetness.
- Mist Vandas frequently until all roots are green and then let them dry out again.
- Be careful not to overwater Vandas, as this can lead to root rot.
- Provide Vandas with very strong light, but avoid direct sunlight during the hottest part of the day.
- Fertilize Vandas at every misting with a balanced fertilizer such as the MSU fertilizer for orchids at the recommended strength.
With proper care, Vandas can be rewarding plants to grow. Neofinetia falcata is one of the recommended species for outdoors and details are provided in the section on orchids recommended for outdoors in San Diego.