The genus Bulbophyllum is the most extensive in the entire Orchidaceae family and currently comprises over 1800 species of orchids, with new species constantly being described and added to this vast genus. It is currently one of the most numerous genera in the entire plant kingdom, with only Euphorbia and Senecio containing more species. In the floral trade, Bulbophyllum is abbreviated as Bulb.
The name "Bulbophyllum" refers to the shape of the leaves. Plants in 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 high and low altitudes in rainforests and cloud forests in most tropical and subtropical countries. They exhibit an enormous variety in their habit, ranging from completely terrestrial species to giant epiphytic climbers. They can flower directly from the rhizome or the shoot, depending on the species.
General information should only be used as a guide to Bulbophyllum care and adapted to your specific needs. You will need to take into account your geographical 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 most suitable cultural methods for you and your plants.
Light
It is difficult to provide specific recommendations, as Bulbophyllum orchids are found in a myriad of different environments. If specific guidelines cannot be found for each species, it can be assumed that the wider the leaves, the less light the plant will need.
Bulbophyllum orchids usually require intermediate light, less than Cattleyas but more than Phalaenopsis. More intense light, which does not damage the leaves, seems to promote better and more frequent flowering. They can be grown indoors, provided they receive good light.
Temperature
They are considered warm-intermediate climate plants. Most require warm temperatures, between 21 and 27 °C, but they are also comfortable within a temperature range of 7 to 35 °C. They do not tolerate frost. They need a temperature drop of about 6-8 °C at night for flowering. Those native to high-altitude areas of Papua New Guinea prefer lower temperatures and may not be suitable for warmer climates. The minimum temperature for tropical forms is considered to be 10 °C and 15 °C for equatorial species.
Water
As mentioned earlier, it is impossible to provide universal guidelines for all Bulbophyllum species. Many of them, 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 allow it to dry only slightly between waterings. If you grow orchids on 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 need abundant water during the active growth phase, and even a dry period of a couple of days is enough to kill new shoots and set the plant back. Due to their thin, shallow root system, they need constant moisture around the roots; however, depending on their origin, some require distinct wet and dry periods to flower. The potting mix should never be allowed to dry out completely. They can be kept slightly drier in winter.
Humidity
Most species come from humid rainforests. Humidity should be maintained at 60%, which can be difficult to achieve outside a greenhouse. Water frequently, as both rafted 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 movement is important to reduce the problem of foliar fungal diseases due to frequent watering. Where natural humidity is high or where humidification maintains a high degree of humidity, increased air movement is essential to prevent stagnant air and the development of diseases.
Flowering
They flower mainly in spring, early summer, or early autumn, but under the right conditions, they can flower all year round. The flowers are small to large and are highly specialized to attract specific insect pollinators, and many have a strong, pungent odor that primarily attracts flies.
Feeding
If you cannot find specific species information regarding the nutritional needs of your Bulbophyllum orchid, try using a balanced fertilizer twice a month. Divisions should only be treated with half the concentration. Seedlings can benefit from a high-nitrogen fertilizer until they are large enough to flower.
Recommended Fertilizers:
- Balanced growth fertilizer: 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
Bulbophyllum orchids can be grown hanging on wood slabs or tree bark. However, all species can be grown in shallow pots or even baskets. A requirement is to maintain sufficient moisture at the roots, as most species do not like to dry out. The rhizome can be trained to stay in the pot by bending it, possibly cutting off old bulbs and leaving them in place, so that they provide additional 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, when it rots or starts to retain too many salts, the plants will have 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 preferable in spring or autumn when new shoots appear at a frequency of approximately every 3 years.
If dividing a plant, one or two pseudobulbs are needed per division. Choose a pot that allows for approximately two years of growth before filling the pot. Carefully cut the rhizomes with sterile tools and then repot. After dividing the orchid, it is crucial 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 humidity levels they require to survive. Fungal agents cause problems such as root rot, leaf spots, leaf dieback, and flower deformities.
