Healthy Zygopetalum start with healthy roots:
- Pot in a fine medium. Fir bark mixtures are best, with 0.5 to 1.0 cm chunks of bark, perlite and charcoal.
- Repot when the medium starts to break down or when the new growth will be over the edge of the pot.
- Remove old medium if it is loose and any rotting roots; choose a plastic pot that will allow for 2 to 3 new growths and position in the pot so that the new growths will grow from the middle to the edge.
- Roots should be moist at all times when in active growth. When the plant is actively growing, water when medium is damp before it has dried substantially. When the plant is completing its growth start to let it dry slightly, to encourage flowers rather than more vegetative growth. When it is dormant water when the medium is still slightly damp. When watering, water thoroughly, with a volume of water at least equal to that of the pot.
- When watering avoid dampening leaves as this may increase leaf spotting and use room temperature or warmer water.
- Do not use water softened in salt-consuming water softeners. Low mineral water is preferred, such as naturally soft water or rain water. If hard water is used, water very heavily to flush minerals.
- Fertilize weakly and frequently with a balanced fertilizer. One-eighth to one-quarter strength recommended by manufacturer for house plants every week in spring and summer and every two weeks in autumn and winter.
Healthy leaves produce more and bigger flowers:
- Medium light levels are appropriate. Leaves should be a light green, not yellowish (too much light) or dark green (too little light). They should be somewhat stiff, not long and floppy (more light needed).
- Two to three hours of sunshine on a windowsill (East or West) or 6-12” under a four tube fluorescent fixture.
- Zygopetalum do best with 50-60% humidity but will grow and bloom at somewhat lower humidity levels. Use humidifier to raise humidity – humidity pans and misting minimally effective. Enclosing plant growing areas is effective but ensure fresh air and air movement to avoid mold and rot.
- Air movement and avoiding humidity over 60% are necessary precautions to minimize leaf spotting on these orchids.
- Grow Zygopetalum in intermediate temperatures with 14°C minimum winter nights and 29°C summer day maximum. Ensure 6-12°C day/night difference to aid flower formation. Avoid temperatures below 14°C as this can exacerbate leaf spotting problems.
Zygopetalum usually bloom annually in the spring and the flowers last for three to four weeks:
- Maintain plant orientation while spike is growing for best display.
- Buds turning yellow, wilting and falling prior to opening is from not enough energy in the plant to open the flower either because the light is too dim, the plant is too small, or the roots have rotted. Also caused by ethylene gas (from ripening fruit) or large temperature fluctuations.