The yellowing of orchid leaves can be normal if they are on the older backbulbs. However, yellow new leaves indicate a sign that the plant is getting too little nutrients or sunlight. Orchids are a particularly sensitive plant that must have their growing requirements met in order to be healthy. Without proper care, your orchid plant has little chance of survival.
Yellowing of Old Leaves
As the orchid ages or if it is transplanted, some of the leaves will yellow and die back. This is a completely normal process for an orchid. However, if yellowing occurs on newer leaves, then your plant may be getting too little or too much sun. Your orchid could also be suffering from inadequate water or nutrients. To be sure, monitor your plant's growth, look at all new growth as it comes in and take a mental inventory of the location of old growth. By keeping up to date on your orchid's growth patterns, you will be able to easier identify old and new leaves.
Too Much Sunlight
Orchid leaves are very susceptible to burning from sunlight. However, if your orchid gets too little sunlight than it won't flower. Keep a proper balance of sunlight by placing your orchid behind a sheer shade or curtain. Move the plant either toward the light if you notice the leaves becoming dark green or away from the light if they begin to yellow. When your orchid's leaves have already turned yellow, keep them in the shade for a couple of weeks. Set them further away from the window or add another curtain to diffuse the light. All orchids have their own light requirements. Research what type of light your specific orchid needs. For example, lady slippers and phalaenopsis need shade, whereas vanda and dendrobium orchids thrive in full sunlight.
Sunlight may not always be the issue. Avoid setting your orchid near any heaters, air conditioners or open windows. New orchids received in the mail should be slowly introduced to sunlight by placing the plant closer to the window every other day. Temperatures also affect the growth of the plant. Make sure that your orchid never gets too hot or too cold. Watch for any drafts in the house and replace your orchid to its growing spot after using it for a centerpiece.
Overwatering Your Orchid
Watering is generally a tricky process for orchid growers. The frequency that you water your orchid depends on your climate or home's temperature. Other factors that determine your watering schedule include size of container, potting medium and how you water your orchid. A 6-inch pot typically needs to be watered every week, whereas a smaller container should be watered every four days. If you use bark as your potting medium, you should check the soil's moisture content more often because bark dries out. Sphagnum moss is able to hold on to moisture without causing root rot to the orchid. Before watering your orchid you should poke your finger several inches into the potting soil. Refrain from watering when the soil is soggy or the top soil hasn't dried out. Yellowing of leaves will occur when you've watered your orchid too much. Withhold water for a week to allow the plant to dry out. Continue a regular watering schedule when you see leaves return to their natural green color.