The genus Bulbophyllum is the largest in the entire Orchidaceae family, currently comprising over 1,800 species of orchids, with new species being constantly described and added to this vast genus. It is currently one of the largest genera in the entire plant kingdom, with only Euphorbia and Senecio containing more species. In the flower trade, Bulbophyllum is abbreviated to Bulb.
The name "Bulbophyllum" refers to the shape of its leaves. Plants of this genus are native to Australia, Southeast Asia, Africa, and South America, with the greatest diversity found in Papua New Guinea. They are found at both high and low altitudes in the rainforests and cloud forests of most tropical and subtropical countries. They exhibit enormous diversity in their growth habit, ranging from completely terrestrial species to giant epiphytic climbers. They can flower directly from the rhizome or from the shoot, depending on the species.
The general information should be used only as a guide to Bulbophyllum care and adapted to your needs. You'll need to consider your geographic location, where you grow the plants, the time you have available for their care, and many other factors. Only then can you decide on the cultivation methods best suited to you and your plants.
Light
It's difficult to provide specific recommendations, as Bulbophyllum orchids thrive in a myriad of different environments. If you can't find specific guidelines for each species, you can assume that the wider the leaves, the less light the plant will require.
Bulbophyllum orchids generally require intermediate light levels, lower than Cattleya orchids but higher than Phalaenopsis orchids. Brighter light, which doesn't damage the leaves, seems to promote better and more frequent flowering. They can be grown indoors, as long as they receive good light.
Temperature
They are considered warm-to-intermediate climate plants. Most require warm temperatures, between 21 and 27°C (70 and 80°F), but they also thrive in temperatures between 7 and 35°C (45 and 95°F). They are frost-intolerant. They require a drop in temperature of about 6-8°C (41-46°F) at night for flowering. Those native to high-altitude Papua New Guinea prefer lower temperatures and may not be suited to warmer climates. The minimum temperature for tropical forms is considered 10°C (50°F) and 15°C (59°F) for equatorial species.
Waterfall
As mentioned above, it's impossible to provide guidelines that apply to all Bulbophyllum species. Many, however, are accustomed to rainy environments and require a lot of water. If you grow one of these species in a pot, you can water your Bulbophyllum orchid every 3-4 days and only let it dry slightly between waterings. If you grow orchids in a raft, you can water them twice a day. If a new leaf is smaller than the old one, your Bulbophyllum orchids need more watering.
Generally, these orchids require abundant water during the active growth phase, and even a dry period of a couple of days is enough to kill new growth and cause the plant to shrink. Due to their thin, shallow root system, they require constant moisture around the roots; however, depending on their origin, some require distinct periods of wetness and dryness to flower. The soil should never be allowed to dry out completely. They can be kept slightly drier in winter.
Humidity
Most species originate from humid rainforests. Humidity should be maintained at 60%, which can be difficult to achieve outside of a greenhouse. Water frequently, as both raft plants (at least once a day) and potted plants (several times a week) will thrive in more humid conditions than most orchids. Bulbophyllum may be the exception to the "when in doubt, don't water" rule.
Good air circulation is important to reduce the problem of fungal leaf diseases caused by frequent watering. Where natural humidity is high or where humidification maintains high levels of humidity, increased air movement is essential to prevent stagnant air and the development of diseases.
Flowering
They bloom mainly in spring, early summer, or early fall, but under the right conditions they can bloom year-round. The flowers range from small to large and are highly specialized to attract specific pollinating insects, and many have a strong, pungent odor that primarily attracts flies.
Diet
If you can't find species-specific information about your Bulbophyllum orchid's nutritional needs, try using a balanced fertilizer twice a month. Divisions should only be treated with half the strength. Seedlings can benefit from a nitrogen-rich fertilizer until they are large enough to flower.
Recommended fertilizers:
- Balanced fertilizer for growth: 20-20-20 (NPK) – 1 gram per liter of water – Spray once every two weeks (14 days)
- High phosphorus fertilizer for flowering: 0-52-34 (MPK) – 1 gram per liter of water – Spray every two weeks (14 days)
Repotting, substrate and propagation
The Bulbophyllum orchid can be grown hanging from wooden slats or tree bark. However, all species can be grown in shallow pots or even baskets. Maintaining sufficient moisture at the roots is essential, as most species do not like to dry out. The rhizome can be trained to remain in the pot by bending it, possibly cutting off old bulbs and leaving them in place so they can provide further growth in the pot. Sphagnum moss is popular because it retains a lot of moisture, which is what these plants prefer during active growth; however, if it rots or begins to retain too many salts, the plants will experience problems.
Bulbophyllum species tend to prefer minimal repotting. The choice of repotting will often be dictated by the very long rhizomes of some species. Repot as infrequently as possible. Repotting is best in spring or fall, when new shoots appear about every three years.
If dividing a plant, you'll need one or two pseudobulbs per division. Choose a pot that allows for about two years of growth before repotting. Carefully cut the rhizomes with sterile tools and then repot. After dividing the orchid, it's essential to keep the plants in a humid place while the roots begin to grow.
Pests and other problems related to Bulbophyllum
Fungal and bacterial diseases of Bulbophyllum are common due to the high humidity levels they require to survive. Fungal diseases cause problems such as root rot, leaf spots, leaf discoloration, and deformed flowers.
