Grammatophyllum Orchid Yuan Nan Tiger

General Care Guidelines:
Grammatophyllum orchids are relatively low-maintenance but require specific conditions to thrive and bloom well. 

Light: They require bright, filtered light, similar to Cattleya or Dendrobium orchids. Morning sun is ideal, while protection from harsh midday sun is necessary to prevent leaf scorch. Healthy leaves should be a lime-green color.

Temperature & Humidity: These plants thrive in warm, humid environments.

Daytime temperatures should range from 22°C to 30°C (72°F to 85°F).

Nighttime temperatures should have a slight drop to around 18°C to 24°C (65°F to 75°F) to encourage flowering.

Humidity levels should be maintained between 50% and 70%, with good air circulation to prevent fungal issues.

Watering: During the active growing season (spring through early fall), they need frequent, heavy watering, allowing the potting mix to approach dryness between waterings. In the cooler winter months, reduce watering frequency. The large pseudobulbs act as water storage, so they should remain plump.

Potting & Media: Use a coarse, well-draining orchid mix containing materials like bark, charcoal, and sphagnum moss. They prefer to be slightly pot-bound, and large specimens are often best grown in wire or wooden baskets due to their extensive root systems. Repot every 1-2 years, ideally in the spring, when the medium starts to break down.

Fertilizer: Feed consistently during the growing season with a balanced NPK (20-20-20 or 15-15-15) fertilizer at half the recommended strength. A high-phosphorus fertilizer (e.g., 0-52-34) can be used to encourage blooming after a brief dry period. Flush with clear water monthly to prevent salt buildup.