🌸 Tolumnia 'BlackBull' Care Sheet (Closed Terrarium Setup)
A compact, high-impact orchid with velvety dark blooms—perfect for bright terrariums with airflow and a keen grower’s touch.
🔍 Quick Info
Type: Miniature epiphytic orchid (Oncidiinae)
Size: 5–12 cm tall
Flowers: Deep red to near-black, glossy or velvety; showy, butterfly-shaped; blooms on tall, wiry spikes
Bloom Time: Spring to early summer, with potential reblooming in ideal conditions
Growth Habit: Tight fan-like clusters with wiry aerial roots
🌡️ Temperature & Humidity
Day Temp: 22–30°C
Night Temp: 16–20°C
Humidity: 60–80%
✅ Thrives in warm, humid air
⚠️ Requires excellent air movement—roots must dry out completely between waterings
💡 Light
Requirement: Bright, filtered to high indirect light
Natural Light: East- or north-facing window
Artificial: LED grow light (12–14 hrs/day)
✅ Light-loving—place higher in the terrarium
❌ Avoid direct sun—leaves burn easily
💧 Watering
Frequency: 2–3× per week in warm months, less in cool periods
Water Type: RO, distilled, or rainwater
✅ Allow roots to dry completely between waterings
❌ Never keep moss wet around roots—leads to fast rot
Method: Mist or dunk roots, then ensure they dry fully
🌱 Potting & Mounting
Best Method: Mounted on cork or driftwood with minimal moss
Alternative: Small basket or mesh pot with coarse bark or LECA
✅ Ensure air exposure for roots
❌ Avoid dense, moisture-retaining media like sphagnum
🌬️ Air Circulation
Non-negotiable for terrarium success
Use USB fan or open lid 2–3× per week
Prevents fungal issues and supports healthy root cycling
🌿 Feeding
Fertilizer: Balanced orchid food, 1/4 strength
Schedule: Weekly during growing season
Flush: Monthly with pure water to prevent mineral buildup
⚠️ Terrarium Care Tips
Mount close to light source and airflow
Remove dead fans to reduce rot risk
Keep spacing around the plant open to promote drying
Roots will appear silver when dry and green when freshly watered
✅ Best For
Bright, well-ventilated terrariums with high humidity
Experienced orchid keepers who understand wet-dry cycles
Collectors seeking dramatic, dark-blooming miniatures