Identifying and Repotting Dendrobium and Phalaenopsis: Light, Water, and Humidity Trays

Question:

Had orchid since June 2006. Photo: [link]. Don't remember flower color/look. Help ID for proper care. Currently on rocks in water tray for humidity.

Answer:

Hello Jamie,

Two questions here.

Photo 1: Looks like Dendrobium—needs repotting (roots appear rotting). Photo 2: Phalaenopsis—if several years old, repot.

Repotting process: Gather orchid media + pruning shears. Remove plant, clean old media from roots, cut soft/mushy (dead) roots. Clean pot, add media to cover bottom, lower roots until bottom leaf just below rim (Dendrobium: bulb base just below rim), center plant, fill with media. Press gently, add more as needed.

Dendrobium likes: Bright light, midday semi-shade. 50–85°F, humidity >40%, light air movement. Evergreen type: evenly moist, not constantly wet (media almost dry between waterings).

Phalaenopsis likes: Bright indirect + couple hours direct early morning sun. 60–85°F, humidity >50%, light air movement. Water when media barely moist.

Both: light feeding (~½ label rate) occasionally. All orchids need light—degree varies. Don't plant in garden, but can go outdoors if conditions met. Pebble tray with water (pot not sitting in water) = good humidity.

Follow-up: Jamie sends more photos: yellow leaf with black spots (fungus worry), another large leaf yellowing. Root/leaf photos attached.

Follow-up Answer:

Larger black spots = sunburn (too much sun). Smaller spots = possible fungus from overnight water droplets. Yellow leaf cause unclear—maybe age. Potting media past prime—replace with fresh. Dendrobiums prefer pot-bound roots (grow/bloom better). Reuse same pot. Media: orchid bark + perlite/sponge rock. Repot: clean roots, remove dead, position bulbs just below rim, fill firmly. Water, warm shade weeks, barely moist, morning mist. Return to growing area—should bloom next year.

Jim Kawasaki
San Jose, CA