Dendrobium trankimianum

Dendrobium trankimianum is a rare orchid species endemic to Vietnam, specifically found in the mountainous regions of Khanh Hòa and Lâm Đồng provinces. It grows epiphytically on tall trees within cloud forests at elevations of approximately 800–2000 meters. Its flowering season typically occurs in April to May.

Features:

• Stems & Leaves: It has thin, cylindrical pseudobulbs or reed-like stems, measuring around 30–50 (to 60) cm in length and about 0.6–1 cm in diameter. Leaves are narrow, ranging from 4 to 8 (up to 10) cm long and 0.7 to 2.2 cm wide.

• Flowers: Inflorescences emerge near the apical nodes, with each producing 1–2 (sometimes 3) widely-opening flowers approximately 3.5–5 cm across. The sepals are narrowly triangular, about 2.8–3.4 cm in length, while the petals are similar in size but broader. The lip (labellum) is 3–3.5 cm long and 2–2.5 cm wide, with erect side lobes and an undulate median lobe, featuring distinctive red or bright-colored disc markings.

• Pollination & Rarity: The flowers are reportedly odorless, and the species is considered Critically Rare (CR) with a highly restricted natural range.

Care Tips:

Light & Placement

• Provide bright, indirect light—ideally near an east- or west-facing window. Avoid harsh midday sun to prevent leaf burn.

Temperature & Humidity

• Maintain warm to intermediate temperatures: daytime around 20–30 °C (68–86°F), with a night temperature drop of about 6 °C (10 °F).

• Aim for moderate to high humidity, around 50–70%, or even into the cloud-forest range (50–60%).

Watering & Dormancy

• Water thoroughly during the active growth and flowering season (spring–summer), letting the roots nearly dry between waterings.

• During a potential dormant winter rest, reduce watering significantly to avoid rot.

Potting & Growing Medium

• Use a well-draining bark-based mix or consider mounting the plant to mimic its epiphytic nature.

• Avoid overly large pots—Dendrobium species tend to prefer being slightly root-bound.

Feeding & Maintenance

• Fertilize with a balanced orchid fertilizer at half strength during active growth. Reduce feeding during the rest period.

• Prune spent flowers and remove dead foliage, while avoiding cutting healthy canes that store energy for future blooms.

• Watch for common pests like mealybugs, scale, and spider mites, especially given the orchid’s rarity and sensitivity.