Orchid species that are typically bathed in sunlight, or grow in areas which are dry and arid, have thick, very leathery leaves, whereas species that live in shaded areas have long, thin leaves.

The leaves on them generally live for several years, while others shed them annually and grow new ones.

What symptoms is your plant displaying?

• Are the leaves turning yellow?

• Do they turn yellow and drop?

• Do they have any Black Rot? (leaves turn black and watery)

One of the most common ailments with these flowers is the presence of yellow orchid leaves. It could be just a sign that your plant is suffering from old age or it could be something more serious. Don’t worry if it’s only happening to the oldest leaves as they could be just drying off. The leaves tell you a great deal about the overall health of the plant, so it’s important to take note of any changes.

Fungal Infections

If you see irregular bright spots on the leaves, this may be the result of a fungal infection, but does not turn the whole leaf to a goldenrod color. The state of the leaves can tell you a great deal about the overall health of the orchid.

Excess Sunlight

One of the most common causes of yellow leaves is too much light. If you have these plants outside, especially where it’s in the midday sun, it can actually have burn spots on the leaves.

Move the plant to an area of filtered light and it will recover in no time. The leaves, however, will stay blonde and will not turn back to the bright green color. You’ll have bright green leaves again once the plant has recovered and there’s new growth.

Cold Temperatures Causing Sickly Leaves

Another reason for yellowing leaves is cold weather. Orchids do not like the cold so move them away from windows or areas where they are likely to be in a draft. If you have them outside, make sure you bring them inside if the temperature drops below 50 degrees F. They need humidity to promote growth, but remember also that high humidity can cause fungus to grow. The ideal temperature for these flowers to thrive is between 75-90 degrees F during the day and no lower than 55 degrees F at night.

Excess Watering Should Also Be Taken Into Consideration

Although not usually the case, too much watering can also cause yellowing of the leaves, but there will also be evidence of Black Rot as well. The only species that prefers constant damp conditions, is the Vandas, whereas the majority prefer to dry out in between watering. If your plant happens to be one in the majority, don’t water for a week or two and treat the plant with an anti-fungal preparation.

Make sure that the environment surrounding your orchids is toxin free, as fumes from products such as paint or cleaning fluids can also cause yellowing of the leaves.

Not Enough Nitrogen in Planting Medium

Do you have enough nitrogen in your fertilizer? Your plant could be suffering from a nitrogen deficiency which is also a cause for discolored leaves. Repot the plant if you think it’s necessary, and allow the orchid to establish a new root system. Once established, apply a nitrogen-based feed at regular intervals.

While waiting for new roots to develop, feed the foliage on a regular watering cycle of once every two weeks, misting the foliage so that minute water droplets cover the leaves like dew. This will return the foliage to a healthy green.