There are several ways to determine why the leaves on your orchid are beginning to yellow. Here is an easy list to go through to determine what is ailing your plant and how to help it.
- The leaves of an orchid can burn and turn yellow if they are exposed to direct sunlight. Make sure to put your orchid in a place that receives sufficient indirect sunlight.
- Overly low temperatures can also cause orchid leaves to turn yellow. Make sure the temperatures around your orchid are between 18 and 27 degrees C in the day and 15 and 21 degrees at night.
- Over watering can lead to root rot, which can in turn cause its leaves to turn yellow. You should only water the plant when the top one inch of the potting medium is dry and the roots are white, and make sure there are enough holes in the pot to allow proper drainage. If your orchid is suffering from root rot but you see your plant still has some healthy green roots, trim the rotted roots and repot the plant in new media. Mist the leaves the first week in place of watering.
- Overuse of fertilizers might be a problem. Use very diluted fertilizer to avoid chemical burn. Stop using fertilizer for a period of time to determine if this is your problem.
Hopefully these points will help you troubleshoot your yellow spots. You can get more information from the American Orchid Society.