Orchid leaves can become yellow due to several reasons. It can be due to being over or underwatered, excess or lack of sunlight, temperature, and mold and pest infections, among other things.
For all of them, the orchid foliage’s yellowing is an outward sign of the roots not getting enough nutrients and water from the soil.
Keep reading this guide to know more about these causes and the things you can do to fix them!
The Causes of Yellowing Orchid Leaves
Here are the possible reasons why your orchid’s leaves are turning yellow and how you can fix them:
1) Intense or Harsh Sunlight
Are your orchids getting harsh straight sunlight at your home? They shouldn’t be, as they prefer shaded or filtered sun—just like in their native tropical environment.
Often the sign of this is you’ll see round yellow marks around the margins of the orchid leaves.
How to Fix it
If this is the case for your orchids, you simply have to move them to a spot where they get bright indirect light.
This could be near north or east-facing windows in your house, 3 or 10 feet away, respectively, because these considerably get a safer and gentler intensity of sunlight.
2) Overwatering
It’s very easy to accidentally overwater any plant. Most people just don’t think about it that much, but overwatering is the number one enemy of all plants, including orchids.
The reason for this is overwatering leads to root rot, a condition wherein the roots become black and mushy, as opposed to being tan or white, fresh, and numerous.
In addition, root rot may accompany other symptoms such as soft and wilted leaves, drooping or falling flowers, and the entire plant looking unhealthy.
How to Fix it
As soon as you notice these concerning signs, scale back your watering.
Alternatively, and this is a great tip: you might want to try watering the orchid with ice. Using three ice cubes should do.
As to the reason why, iced water is taken in at a slower rate by the soaked-through orchid, preventing you from over or underwatering it.
This is validated by the joint research efforts of Ohio State University and the University of Georgia.
Anyway, if most of the roots have rotten, then you’d have to repot the orchid plant in new potting soil if you want to save it, lest the fungal root rot spreads to the remaining roots.
3) Cold Temperatures
Your orchid leaves can also gradually turn yellow because of a cold ambient temperature that’s below 65℉.
What’s amazing about orchids is they bloom all year round, even during the winter, though they have to be protected from cold temperatures still.
But don’t worry. As long as frost doesn’t develop on the orchids, they won’t be affected by it.
How to Fix it
Remember that these decorative plants need to be grown indoors at 75℉ to 85℉ during the day and 65℉ to 75℉ during the night.
Along with this, make sure to keep the humidity level between 40 and 80 percent, as they’re used to this in their growing environment.
Adjust your thermostat accordingly, and your orchid plants should grow healthily and not develop any yellow spots or patches.
4) Plant Disease
The yellowing of the orchid leaves can also have been brought about by plant disease. Specifically, this can be a bacterial or fungal disease.
There’s an easy way to tell which of these two illnesses has affected your plant.
If you observe spots that are usually black, brown, gray-pink, or yellow with a rough texture, the orchid must have a fungal disease. At first, the marks show on the lower side of the leaves and then slowly spread to the upper part.
Whereas, if the orchid emits a malodorous scent, then it is most likely rotting from bacterial infection.
How to Fix it
Since plant diseases are contagious, you must quickly move them away from other plants.
Now sterilize a pair of garden scissors and cut out the infected part of the plant. Most of the time, it is usually better to dispose of the entire plant if it is badly infected.
Afterward, decontaminate the plant with a mild or natural plant pesticide, and it should now be safe to return to its original location.
5) Nutrient Deficiency
Same as all humans and plants, indoor orchids cannot function well if they are deprived of nutrients.
Plant nutrients are grouped into macronutrients and micronutrients. The first are nitrogen, phosphorus, and potassium, and the latter are iron, zinc, calcium, and chlorine, just to name a few.
Here’s what these certain nutrients do for plants:
Macronutrients
- Nitrogen – This allows the plant to capture and store solar energy to use for its biochemical processes and growth. These processes includes photosynthesis, which is the process of making food for it to survive.
- Phosphorus – It’s another essential nutrient that facilitates root growth, strengthens stems, helps the plant bear beautiful flowers, and resists pests and diseases.
- Potassium – Also called potash, potassium enhances the movement of water, nutrients, and sugar within the plant that help it to function normally and also speed up photosynthesis.
Micronutrients
- Iron – This mineral is essential for the plant to produce chlorophyll, the pigment allowing it to have and maintain its green color.
The lack of iron is therefore one of the usual causes for the plant’s leaves to become yellow.
- Zinc – Young plants need zinc because this assists with the synthesis of enzymes and growth nutrients. With zinc, their metabolic reaction speeds up, meaning they can absorb more beneficial nutrients.
- Calcium – Next, calcium helps plants have healthy cells and tissues so that they grow strong and beautiful.
They also stimulate certain enzymes that communicate with other cells to carry out a certain biochemical function.
- Chlorine – This regulates the stomata of the plants through which the exchange of water and carbon dioxide in and out of them takes place.
Aside from that, it helps to increase the plant’s resistance to diseases and bugs and facilitates food-making.
Among the symptoms of nutrient deficiency are wilting, yellowing or bronzing leaves (a condition known as chlorosis), and thick and short roots.
How to Fix it
Although orchids don’t need much plant food, you have to feed them still since fertilizer supplements them with nutrients that are necessary for their growth and flowering.
There are lots of options out there, but make sure you pick one that is made especially for orchids. We strongly recommend giving orchids a nitrate-rich formula for best results.
According to this study done for the American Society for Horticultural Science, nitrate is a compound with nitrogen that encourages larger flower development and better magnesium and calcium intake.
The latter helps the plant grow and carry out photosynthesis.
You’re meant to feed the plant with fertilizer every week while it is growing. But first, dilute it to one-half dosage so it won’t come out as too strong for the orchid.
And when winter comes around, reduce your feeding to just once a week and use less plant food.
6) Natural Aging
Finally, an orchid can also have yellow and falling leaves in time because of age. However, this is perfectly natural if you have taken care of your orchid pretty well.
Hence, you don’t have to do anything about it apart from regular watering, pruning untidy or dead flowers, and feeding it with special orchid fertilizer.
What is the best soil to use for orchid flowers?
The best soil for orchid flowers should contain some of these ingredients: sphagnum peat moss, coco coir, shredded wood bark, charcoal, perlite, pumice, cork nuggets, rock wool, and vermiculite.
The combination that you should go for will depend on the kind of orchid you own, whether it is epiphytic, lithophytic, or terrestrial.
Epiphytes and lithophytes prefer a soil mix with mossy roots, and terrestrials thrive in denser soil with sphagnum peat moss, coco coir, and sand.
Here are two recipes you can use for the specific type of orchid you have.
1. Bark Soil Mix
- 5 parts fir or pine bark
- 1 part sphagnum peat moss
- 1 part perlite
This one is a soil-less mix made primarily with pine bark.
The tree bark will make the soil loose enough to allow water and air an easy passage. Plus, perlite will boost the orchid’s nutrient and moisture retention.
This is a lot better than using a soil-based potting medium for your orchids since the latter isn’t the same as those in their natural environment and has some issues when it comes to drainage and aeration.
2. Coco Coir Soil Mix
- 2 part coco coir
- 1 part charcoal
- 1 part perlite
You can also try this recipe of coco coir soil mix. This excellent soil mix consists of 2 parts coconut husk chips, 1 part perlite, and 1 part charcoal.
Coco coir will improve drainage and water retention at the same time, perlite retains more nutrients for the plant, and charcoal enhances the aforementioned things.
How do I save an orchid with rotten roots?
Follow the steps outlined below to repot your orchids and save them from root damage:
- Choose a great orchid potting medium.
- Gently tilt the pot to the side and pull the orchid out of the pot vessel.
- Fill the pot vessel 1/3 full with the orchid soil.
- Set single-stemmed orchids right in the center of the pot.
- Place the multiple-stemmed orchids against the pot wall.
- Cover the roots with more soil. It should be 1/2 inch below the top of the pot. You may need to stake the orchids that cannot easily balance.
- Water the orchids thoroughly to establish them
