An orchid whose leaves begin to turn yellow is not an uncommon problem so don't panic if this begins to happen to your first orchid plant.
Yellowing orchid leaves are a good indicator that your plant is stressed and needs some attention.
First it is good to recognize the aging process will turn some leaves yellow and allow them to fall off the plant.
If the leaves that are yellow are located on the lower part of the plant, it is doubtful you have any problems.
However, yellow orchid leaves may indicate your plant has some type of disease.
If the yellowing appears as spots on the leaves and if these spots are outlined in black, then you may have a fungus problem.
To control fungus, purchase some Physan and apply as directed and you should see the fungus begin to clear up.
Another cause of yellow orchid leaves is too much sunshine.
Orchids love and need plenty of sunlight but filtered, indirect light is best.
Too much intense sunlight can burn the leaves and this shows up as yellow spots.
Too much sunlight is generally easy to resolve.
Simply move your orchid to a place with a bit less light, perhaps to an eastern facing window that captures early morning sunshine and shields it from the intense mid day sun.
Moving the plant to reduce the intensity of sunlight keeps the problem from continuing but it does eliminate the yellow spots already on the orchid's leaves.
This will take time.
Finally yellow leaves on an orchid may indicate too much water or the ambient temperature is too cold for the plant.
Check your plant to see if the roots are decaying and water less frequently.
If you have severe root decay, repotting may be necessary.
Orchids thrive in a temperature range of 60 degrees Fahrenheit to 85 degrees.
If your plant is in temperatures outside this range, move it to a more moderate environment.
While yellowing orchid leaves is not something you should ignore however the causes of this problem are usually quite manageable.