Orchid Leaves Yellow Edges

Orchid Leaves Yellow Edges

The most common reason for the edges of your orchid’s leaves to turn yellow is a nutrient deficiency – specifically potassium. You will often see patches and spots of yellow on the tips and edges of the plant’s leaves in this case.

You can remedy a lack of potassium by feeding the plant with a balanced fertilizer made specifically for orchids.

In this article, we will discuss the reasons your orchid’s leaves might develop yellow edges, and what you can do to remedy this. We will also discuss the causes of yellowing orchid leaves in general, so that you can differentiate between these various discoloration problems.

Why do my orchid’s leaves have yellow edges?

Orchids do not need to be fertilized as much as most other plants, which is why it may be easy to neglect that aspect of your orchid’s cultural care.

Sometimes, the nutrients present in the orchid’s growing medium become depleted. If they are  not replenished, the plant will develop a nutrient deficiency and the tips of its leaves will become discolored.

Common deficiencies include nitrogen, iron, zinc and manganese, but the most common is potassium. All of these nutrients are essential in the orchid’s life cycle.

You can remedy a nutrient deficiency in an orchid by feeding the plant twice a month with a balanced fertilizer. Make sure, however, that you only fertilize the plant while it is actively growing. Refrain from feeding it during the winter because this can lead to possible toxicity due to a mineral buildup in the potting medium.

What else causes yellowing orchid leaves?

1. Too much light

In their natural habitat, many orchids live in the rainforests, growing on the sides of trees and protected from the harsh sunlight by the forest canopy. These plants only ever get stippled sunlight in the forest. This is why, when orchids are grown in homes, they should be placed in spots where they only get bright, indirect light.

If your orchid gets too much direct light, the leaves will turn yellow and may also get sun-damaged.

Fortunately, it is very easy to fix this problem. All you need to do is transfer the plant to a spot where it will not get such harsh light.

Keep the plant near a north- or east-facing window in the summer, and transfer it to a south- or west-facing window during the winter. If the only window available is letting in harsh light, you can diffuse the intensity by placing a sheer curtain over the window.

2. Temperature changes

Try to keep your orchid in a room with temperatures between 60 and 80 degrees Fahrenheit. This may seem daunting, but it is pretty much just room temperature in most US homes.

If the ambient temperature falls below 60 degrees or goes higher than 80 degrees, the orchid may suffer from temperature stress, leading to the yellowing of the leaves.

Avoid temperature stress by using a thermometer to monitor the temperature in the room where the plant is kept. If the area is too hot or too cold, find a different spot in the house that is more suitable for your plant.

3. Overwatering

The leaves on your orchid will turn yellow if it is overwatered, because the roots have been compromised and are no longer able to absorb water and nutrients effectively.

Overwatering also leads to root rot, which can eventually kill all the roots of the plant.

You can revive an overwatered orchid by correcting your watering routine and making sure you let the potting medium dry out between waterings. If there are dead or dying roots, remove them using sterilized pruning shears.

The best way to know when you need to water your orchid is by touching the potting medium. If the medium is still damp, wait one or two days and check it again. If the potting medium is dry, you can water the plant.

It is much more difficult to overwater a plant when the pot has drainage holes at the bottom and when the potting medium is well-draining.

4. Transplant stress

When you buy an orchid from a store, you are taking it away from living conditions that it has been accustomed to for months. You might notice that the plant’s leaves turn yellow after a few days of living in your home. Do not worry; this is completely normal and is just a case of the plant trying to adjust to its new surroundings.

Remember that plants are grown in near-perfect conditions in nurseries and greenhouses. So, the moment they leave this pristine environment, they will become stressed by the sudden changes in light, temperature, humidity and watering schedule.

The best thing you can do in this situation is make sure that you are simulating, as closely as possible, the plant’s ideal conditions. The plant will soon get used to the changes and the discoloration will sort itself out.

5. Overfeeding

Orchids do not really need to be fertilized, so overfeeding can be a very easy mistake to make. Adding too much fertilizer to the potting medium leads to an excess of nutrients and minerals, which is ultimately not good for the plant. If the plant absorbs too much of certain nutrients, it will stop absorbing iron. Iron chlorosis manifests as the yellowing of the plant’s leaves.

You can remedy this situation by doing proper research on correct orchid fertilization.

Dilute the fertilizer to half- or quarter-strength; even better, use fertilizer that is made specifically for orchids.

You can also flush out any mineral buildup by letting water flow through the potting medium.

Fertilize your orchid after its blooms have dropped to help the plant regain the nutrients it used to produce the blooms.

Disease

Bacterial brown spot

Your orchid may have bacterial brown spot if there are yellow or brown spots on the leaves. This is most commonly found on orchids that are kept in hot and humid areas. The stress of the disease causes the leaves to turn yellow.

Treat the plant by removing as many of the infected leaves as possible. Make sure you use sterilized scissors to do this. Use a bacterial spray on the plant to protect it from other infections and to prevent the spread of the disease.

Fungal leaf spot

Fungal leaf spot causes yellowing of the undersides of the orchid’s leaves. If you do not treat this disease as soon as possible, these spots will coalesce and form larger brown or black patches.

Remove the affected leaves and dispose of them properly so that the fungus does not infect your other plants. Spray down the plant with a fungicide to kill the fungus and to protect it from reinfection. Make sure you quarantine the plant from your other plants while you treat it.

Root rot

Root rot happens when compromised roots are attacked by opportunistic pathogens. These pathogens cause the rot to spread to the rest of the plant at an alarming rate, and before you know it, the entire plant can be affected and may not be salvageable.

Rotten roots are brown or black in color and soft and mushy to the touch.

You can salvage the plant if there are still white or green roots remaining after you have cut off all the rotten roots.

Natural process

The yellowing of an orchid’s leaves is not necessarily pathological. Quite often, the leaves are turning yellow simply as part of the plant’s natural life cycle.

The most mature leaves and stems of the plant will turn yellow and die in order for the plant to concentrate its resources on producing new growth.

These old leaves will simply fall off after some time.

You will know the yellowing is natural if only the lowest leaves are affected by the discoloration. If the leaves at the top are turning yellow, it is most likely not due to natural dieback.

Refrain from forceably removing the dying leaves. Wait for them to fall off, because removing them prematurely can lead to increased risk of diseases.

Conclusion

Orchid leaves’ edges will turn yellow when the plant has a nutrient deficiency. This is often a potassium deficiency that can be remedied by the application of a fertilizer made specially for orchids.

Other causes of yellowing orchid leaves are too much light, overfeeding, overwatering, disease, temperature changes, transplant stress and natural processes.

The best way to prevent the yellowing of orchid leaves is to make sure you are caring correctly for your plant and protecting it from outside factors such as disease. The better you can simulate the living conditions of the orchid’s natural habitat, the happier the plant will be.

Image: istockphoto.com / alexytrener