Wrong watering is the most common cause of orchids leaves turning yellow.
1. Water the orchid only in the morning.
2. The basic rule of watering frequency: once a week in the winter and twice a week in the summer.
3. Orchids that have tight pots are watered a little more often than those in larger pots.
4. The decision of a new watering depends on how wet is the substrate from the pot surface. The substrate can still be moist inside. For extra safety, stick a wooden pencil in the pot. If it feels moist after removal, it means watering should be postponed.
5. Rainwater is the best because it gathers dust, pollen and other organic materials that contribute to plant nutrition. Tap water should be used with caution because it is subject to chemical treatments.
6. Orchids are always watered room temperature water. Even if the effects are not immediate, watering with cold water are causing serious physiological disorders that lead ultimately to the orchid’s death.
7. Don’t water the orchid leaves. If you accidentally water them, remove it with a paper towel.
8. The rosette is always kept dry. Stagnation of water in the middle of the rosette is equal to a death sentence. If water somehow gets there, it must be removed immediately with a paper towel or with ear sticks.
9. Excessive watering leads to yellowing of the leaves. If you notice signs of leaves yellowing and roots rotting, watering should be stopped for a few weeks.
Image Credits: RV-Orchidworks