Why Are the Leaves on My Phalaenopsis Turning Yellow

Yellowing leaves on a phalaenopsis are not necessarily a cause for alarm. It's normal and natural for older leaves to yellow and gradually drop off. Older phalaenopsis often have somewhat elongated stems where old leaves have dropped away. On healthy plants, new roots will continuously emerge from the stem, eventually forming a mass of roots.
However, if the leaves are yellowing from the top of the plant, there is a problem.
If the leaves are still plump and firm, the plant is most likely receiving too much light and it's washing out the color. If the leaves are wrinkled and listless, the plant is most likely dehydrated.
Yellow Leaves

If the leaves on your Phalaenopsis orchid are yellow, it could be an indication that something is wrong. There are a number of factors that can cause the leaves of an orchid to become discolored, including direct sunlight, low temperatures, and root rot.
Once any yellowing is discovered, it is time to figure out if there is a problem with the plant. If you discover the yellowing leaf is located on the bottom of the plant, don’t worry. This is a natural process of the plant to discard the mature leaf in order to produce a new leaf. However, if multiple leaves are turning yellow or top leaves are yellow, your plant may be sick.
3 Reasons Why Your Phalaenopsis Leaves Are Yellow

The first step is to isolate the plant away from any other orchids that you may have to ensure that they do not become ill as well.
Here are 3 steps to take to try to determine the problem:
Direct sun may be the culprit. The leaves of a Phalaenopsis orchid can burn and turn yellow if they are exposed to direct sunlight. Try putting your orchid in a place that receives sufficient indirect sunlight.
Is the temperature right? Overly low temperatures can also cause orchid leaves to turn yellow. Make sure the temperatures around your orchid are between 65 and 80 degrees Fahrenheit during the day and 60 and 70 degrees at night.
Check the roots. Overwatering 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.
A Tip to Prevent Overwatering

Overwatering is one of the most common problems and one of the most serious Here's a hint to make sure that in your quest to keep your orchid happy, healthy and beautiful that you don't overwater.
To avoid overwatering, we recommend watering your Phalaenopsis orchid with three ice cubes once a week so that the roots will soak up water slowly.