🌿 General Information

The genus Dendrobium is one of the largest in the Orchidaceae family, with over 900 species native to all of East Asia, from the Pacific to the Himalayas, as far as Australia and New Zealand. They live in extraordinarily diverse habitats: from sea level up to 3500 m altitude, in temperate, tropical climates, or with constant humidity all year round. 🌍

Sizes range from tiny plants of 3-4 cm to specimens several meters long. Some species have evergreen leaves, others deciduous; some produce single leaves, others in clusters. Numerous hybrids exist on the market.

A common feature across all groups is the production of keikis — new plantlets that form at the nodes or at the base of the stem. Once sufficiently large, they can be detached and repotted independently. 🌱

Dendrobiums have a rapid vegetative period (they quickly develop green parts and roots) but take longer to flower. Vegetative dormancy corresponds to unfavorable seasons (cold and drought), during which the plant lives off reserves accumulated in the pseudobulbs.

Given the vast variety of habitats, it is impossible to generalize cultivation techniques. For this reason, Dendrobiums are divided into six groups.

🌻 Group 1 — Deciduous Leaf, Cool Greenhouse, Vegetative Rest

Main species: D. nobile, D. chrysanthum, D. wardianum, D. victoriae reginae and their hybrids (e.g., D. nobile × phalaenopsis, D. nobile × bigibbum). Native to Southeast Asia (Nepal, Bhutan, northeastern India, Burma, Vietnam, Laos, southern China) between 200 and 1500 m altitude.

They lose their leaves during the cold, dry period, living off the reserves in their pseudobulbs. With warmth and rain, they quickly recover and prepare for flowering.

• Nov–Feb: cool greenhouse (~10°C), very bright location, very little water (only if stems shrivel), no fertilization, excellent ventilation. Lower temperature = less water.
• Spring (bud emergence): some watering until the end of flowering. After the last flower, suspend irrigation until new roots appear.
• Spring–Mid-summer (Aug): return to a warm area, resume watering and fertilization. High-nitrogen fertilizer (1/2 g/L, 1×/week). Not too intense light. Possible outdoor cultivation.
• Mid-summer–Autumn: low-nitrogen, high-phosphorus, high-potassium fertilizer (1/2 g/L, 1×/week).
• Humidity: ~80% in summer, gradually reduced to 60% in autumn, suspended in winter.
• Repotting: when new roots appear or immediately after flowering.

⚠️ If there is no cold/dry – warm/humid alternation, the plant will not flower and will produce keikis instead of flowers.

🌻 Group 2 — Deciduous Leaf, Intermediate Greenhouse, Vegetative Rest

Main species: D. anosmum, D. findlayanum, D. pierardii, D. parishii, D. heterocarpum, D. aggregatum.

Like Group 1, they lose their leaves in winter. They are cultivated in the same way, with the only difference being that temperatures are more constant throughout the year: nighttime around 12-14°C.

Vegetative rest (autumn–winter) is essential for flower induction: gradually reduce watering to the bare minimum, suspend fertilization. When buds appear (spring), gradually resume watering and fertilization. In spring-summer: lots of light and good air circulation.

🌻 Group 3 — Evergreen, Intermediate Greenhouse, No Rest (but seasonal change)

Main species: D. chrysotoxum, D. densiflorum, D. fimbriatum, D. moschatum, D. thyrsiflorum, D. farmeri.

They should never be left completely dry. In autumn-winter, reduce watering (without suspending it) and place them in a cool spot with nighttime temperatures of 10-12°C. In spring, gradually increase watering, fertilize generously, and move to warmer, brighter environments. Cultivate them like Cattleya.

🌻 Group 4 — Evergreen, Intermediate Greenhouse, Short Vegetative Rest

Main species: D. daerei, D. loddigesii, D. infundibulum, D. sanderae, D. formosum, D. lyonii, D. macrophyllum, D. schuetzei.

Nighttime temperatures: ~12°C in winter, 15-16°C in summer. They do not tolerate temperature extremes. Provide a rest period of about 3 weeks with very reduced watering and no fertilization. When new shoots appear, gradually resume watering and fertilization, always allowing the substrate to dry between waterings.

🌻 Group 5 — Evergreen, Intermediate Greenhouse, No Rest

Main species: D. stratiotes, D. taurinum, D. undulatum, D. veratrifolium, D. gouldii.

They do not like extreme conditions: they prefer moderate temperature and humidity, plenty of light, and good ventilation. Regular watering and fertilization throughout the year, with a slight reduction in winter. If buds drop prematurely, slightly increase the nighttime temperature.

🌻 Group 6 — Evergreen, Warm Greenhouse, No Rest

Main species: D. phalaenopsis, D. superbiens, D. bigibbum and their many commercial hybrids.

Native to the tropical areas of southeastern Australia: hot and humid summers, dry winters. They do not go into vegetative rest: water all year round.

• Spring–Summer (active growth): water abundantly, fertilize 1×/week with high nitrogen (1/2 g/L). Nighttime temperatures 22-25°C, daytime 28-30°C. Humidity 60-70% (mist regularly). Direct sun only in the early morning, shaded for the rest of the day.
• Late Summer–Autumn: high-phosphorus and potassium fertilizer (1/2 g/L, 1×/week).
• Autumn–Winter: gradually reduce watering (allow to almost dry between waterings), suspend or reduce fertilization. Humidity 60-70% with misting. Plenty of light (in nature, winter light is more intense). Nighttime temperatures 12-14°C, daytime 15-18°C.
• After flowering, reduce watering until new flower spikes form.

Do not cut the stem after flowering: it can rebloom, produce side shoots, or generate a keiki. Use small pots with many drainage holes. Substrate: cork and fir bark. Repot after flowering or at the beginning of vegetative regrowth. For division, leave at least 3 pseudobulbs per plant. 🪵

Note: D. bigibbum and D. phalaenopsis, often confused, are distinct species. D. bigibbum is closer to the equator and requires higher temperatures, especially in winter. It has smaller flowers with a larger, more rounded labellum.

💧 Watering and Humidity (general rules)

Always water in the morning to allow leaves to dry before night and prevent diseases. Avoid water accumulation in the leaf axils. To increase indoor humidity, place the pot on a saucer with expanded clay and a little water at the bottom (roots should not touch the water). Mist the leaves once a day. Equip radiators with humidifiers to prevent overly dry air. 💨

Optimal humidity varies by species and temperature: warmer = more humidity, but always with good ventilation to avoid stagnation and diseases.

⚗️ Fertilization (general rules)

Use fertilizers dissolved in irrigation water (preferably not tap water). Always thoroughly wet the substrate before fertilizing to prevent excessive salt concentrations. 🌱

🪵 Repotting (general rules)

Before repotting, thoroughly water the plant to make the roots more elastic. Remove all old substrate and cut dead roots with sterilized tools (alcohol or bleach, preferably flamed). Treat every cut surface with broad-spectrum fungicide powder. Wash the new substrate by soaking it for a few days to remove dust and impurities. ♻️

If roots adhere to the pot, immerse it in warm water for 30 minutes. If that's not enough, cut the pot — do not force the roots. Choose a pot with adequate drainage holes and leave some space between the roots and the rim. After repotting, keep the plant away from direct light and temperature fluctuations for a few days, without watering, to promote healing. Resume normal cultivation when root activity restarts.