If your orchid's leaves aren't feeling well, they'll tell you what the problem is. All you have to do is correctly interpret what they're saying to you in order to care for them properly. Keep a close eye on your orchid and check the leaves over every day, front and back. Often leaves turn a sickly yellow hue when the problem is nothing more than a sign that it's receiving too much love from its keeper in the form of over-watering. Sometimes all an orchid plant needs is a more appropriate location in your home. So before you mortgage the farm and clear your shelves of chemicals, consult your plant's leaves and try a few simple, quick fixes.
Wipe dust from your orchid's leaves gently with a soft cloth moistened with rain or bottled water every day. Not only will this keep the plant's appearance attractive, grooming it will give you the opportunity to look leaves over for problems.
Use a fresh razor blade to cut the yellow portion from a partially discolored orchid leaf. If the entire leaf is yellow, remove it at the stalk. The most common cause of yellow leaves is too much light, and possible exposure to unacceptably low temperatures. Try moving the plant to a warmer spot with less lighting. If only the plant's oldest leaves are turning yellow, it's probably just an aging thing that you don't need to worry or do anything about. If yellowing of younger leaves continues, the plant may need more nitrogen in its diet.
Check your orchid plant's leaves every day for the presence of tiny reddish-brown spots which will quickly turn black. This is probably due to a fungal infection, encouraged by excessive humidity. Try reducing your humidifying methods accordingly. Remove the affected leaf and treat the plant with a fungicide. It's integral to follow all packaging instructions carefully.
Watch leaves displaying small dark brown spots or blotches carefully day to day. If they begin to enlarge, then there's probably a fungal or bacterial disease afoot. Remove the affected portion of the leaf and treat the plant with fungicide. Please follow the manufacturer's recommendations carefully.
Look the affected leaf over front and back if its tip or edges are black or brown. This is almost always caused by an overdose of minerals present in the orchid's water. It's particularly common in homes using well water. Switch to either rainwater or bottled water for your plant.
Examine the entire leaf carefully if you see it tipped or edged in dark brown or black. If the inner portion of the leaf's surface is visibly darkened also, then sunburn is your culprit. Move the orchid away from any direct sunlight and cut off affected leaves.