10 Reasons Orchid Leaves Turn Yellow and How to Fix It

Orchid leaves turning yellow isn’t uncommon, but it may be a sign your plant needs a little help. In my experience, the most common causes are overwatering, followed by excessive light exposure. Some causes of leaf yellowing can threaten the plant’s life, but they’re all reversible if caught in time. I’ve had success fixing the issue by adjusting my watering routine, light exposure, and temperature around the plant. Here, I’ll share 10 of the most common reasons your orchid leaves are turning yellow and tips on how to remedy each.

1) High or Low Temperature

Orchids are even more sensitive to the ambient air temperature than most tropical house plants and flowers. Even a few hours of temperatures that are too high or too low can result in yellowing leaves. Unless you’re raising orchids grown outdoors or with known hardiness, orchids grown indoors should always stay above 60 degrees F.

Short dips below this level are more than enough to cause yellowing and other signs of stress. Avoid temperatures above 75 to 80 degrees F for most common orchid species, especially in enclosed areas where humidity could spike or fall. Cool temperature orchids, in particular, including Odontoglossum, Cymbidium, and Dendrobium.

2) Humidity Levels

Most types of orchids like some humidity, but they’re also prone to growing bacteria and mold on their leaves when there’s too much moisture in the air. Combine high humidity with high temperatures, and you’ll see your orchid quickly yellowing and losing leaves.

The problem is that indoor humidity levels vary daily and can change rapidly. You might set up a humidifier in the morning of a dry day and find your orchids far too humid by the evening.

Sensors that track the ambient humidity level and adjust humidifiers or passive methods like water trays often work better than constant humidification. Most orchids need 40% to 70% humidity, but this varies by the species.

3) Over-Watering

As epiphytes, most orchid species nestle in the trunks and roots of trees to keep their roots relatively dry. Adding a little too much water to your orchid’s pot can smother the roots and cause immediate yellowing of leaves within a few hours to days (and may also lead to common orchid plant pests, bugs, and diseases).

You may notice leaf growth slow and stop first, or the yellow color may be the first sign of trouble. Save overwatered orchids by removing the growing medium and trimming away any black and softened roots. Using a fast-draining pot with a loose soil medium made for orchids and cacti is essential to preventing this common cause of yellowing.

4) Under-Watering

If you’re too afraid to water your orchid when needed, you’ll notice leaves getting soft and yellowing (we generally recommend not watering orchids with ice cubes). They’ll wrinkle, dry up, and the entire stem may wilt or soften. Orchids won’t recover immediately from underwatering, so don’t give up if the plant loses most or all of its leaves before recovering. Ensure the humidity level stays steady and high during a re-watering phase to ensure the plant isn’t losing most of its water out into the air.

5) Seasonal Changes

Since there are dozens of common causes for an orchid to yellow, seasonal changes are hard on the plants. A change in the seasons naturally brings fluctuations in temperature, humidity, light, and more. If you can restore the correct conditions, a slight yellowing from the change shouldn’t linger long.

6) Too Much or Too Little Light

Yellowing in response to light levels is tricky because it’s caused by both too much and too little exposure. Orchids aren’t light-loving plants because they naturally grow in the shade of trees. Some of the most delicate orchids need entirely indirect sunlight, or they’ll burn and yellow quickly.

Yet most orchids still need enough indirect sunlight to grow. Most growers prefer shade cloth and screens to supply light that isn’t direct enough to burn.

7) Nutrient Deficiencies

Orchids aren’t heavy feeders, but they’ll yellow eventually if left too long without feeding. First, you’ll see a lack of flowering and slow to stalled leaf growth. Use an orchid-specific fertilizer and aim to only apply ½ of the recommended dose at first.

Orchids often struggle to absorb iron when you add too much nitrogen and magnesium. This will cause yellowing from the middle of the leaf outward. In this case, you’re dealing with too much fertilizer rather than too little.

8) Plant and Leaf Age

As the plant gets older and each leaf reaches the end of its life, yellowing is inevitable. All orchid leaves turning yellow eventually die off. There’s no harm to the plant by letting a leaf turn yellow and dry up.

You can always trim them off once they start to change color to keep the orchid looking fresh. Check out the newest leaves. Are they dark green, well-formed, and rapidly growing? Then yellowing is likely just a byproduct of the natural aging process. When there are no new leaves forming, and the current ones are losing their color, the cause is likely elsewhere.

9) Fungal and Bacterial Infections

Changes in temperature and humidity levels leave the orchid open to attack from fungus and bacteria. High temperatures and high humidity levels are particularly damaging when fungal spores are present. Leaves attacked by fungi and bacteria tend to yellow over the entire surface or from the tip.

You may not see the fungus if it’s in the soil, destroying the roots. Try letting the plant dry out from overwatering and switching to a new sterile planting medium. Treatments for surface infections won’t save yellowing leaves, but they will stop the spread.

10) Potting Stress

Don’t change your orchid’s pot more than necessary. Orchids like to be somewhat cramped in their surroundings. If you see tightly packed roots that are green and healthy, you still don’t need a larger pot yet. Dry roots will turn white or gray when it’s time to actually repot.

Unnecessary potting often leads to yellow and dead leaves. Of course, waiting far too long for repotting will also stress the orchid. Try to time the repotting cycle based on its growth, so it’s crowded but has space to grow. Aim to repot at least once every two years to refresh the broken-down growing medium.

Tips, Cures, and Remedies

With proper care, orchids can live for years and will happily rebloom under optimal growing conditions. If you notice orchid leaves turning yellow, check the roots first. Gently remove the plant from its pot and look at the roots and stem. If the roots are white, gray, or black, adjust your watering routine accordingly.

Healthy roots indicate the yellowing comes from nutrients, temperature, or humidity issues. Adjust the conditions around the plant and give it a few weeks to recover. You may want to build a recovery enclosure that is easy to keep at the perfect temperature and humidity. This can help you nurse an ailing orchid after letting it dry out or get too wet.

Above all, don’t panic if you see yellowing. Trying too many fixes at once will stress your orchid more than help it. Take your time trying to determine the cause before adjusting anything.

Wrap-Up

Don’t let your beautiful orchid turn from green to yellow just because of a few small mistakes. With attention and care, it’s possible to nearly prevent leaf yellowing. Expect to eventually see one or two orchid leaves turning yellow as the plant ages.

Fertilizing and keeping the temperature perfect won’t stop the leaves from dying one day. But with proper care, your orchid should have many more replacements before any old leaves turn yellow.