Whether you have one Phalaenopsis orchid or an extensive collection, you will have to deal with yellowing leaves.
This can be a jarring experience for the new orchid owner.
In this article, we discuss some of the reasons your Phalaenopsis (moth) orchid may develop yellow leaves. We review some simple steps you can take to deal with this common problem.
What Causes the Condition of Yellow Leaves in Phalaenopsis Orchids?
Phalaenopsis leaves turning yellow, overall is not a big problem. In some mature plants, older leaves will turn yellow and fall off after a certain period of time passes.
As Phalaenopsis orchids mature the plants will develop elongated stems and the older leaves turn yellow and fall off.
If the plant is healthy, new roots will grow from these elongated stems. After a while, a mass of aerial roots will form giving your plant a great deal of character.
Should I Cut Off the Dying Leaves on a Plant?
The plant will drop old leaves on its own. If you don’t like the appearance of the leaf, you can hurry the process by trimming the leaf off. Be sure to use a sterilized blade or scissors for this process.
Should You Worry About Yellowing Orchid Leaves?
To determine whether you have anything to worry about, begin by examining the plant. If the yellow leaf is at the base of the plant, you have nothing to worry about. The bottom leaves turn yellow because they are the oldest.
New leaves of Phalaenopsis grow from the crown. If leaves at the top of the plant are turning yellow, it could be a sign that you need to change your care routine. It could indicate that your plant is ill.
Why Are the Leaves on My Phalaenopsis Turning Yellow?
Some reasons that contribute to yellowing leaves include:
#1 – Too Much Direct Sunlight:
With Phalaenopsis orchids, direct sunlight can burn the leaves and cause them to turn yellow. Examine the leaves.
If they are yellow but firm and plump, this is an indication that your plant is just getting too much direct sunlight. Sunburned leaves have an unevenly faded, splotchy appearance.
Try moving your plant into an area with bright indirect sunlight. This would either be set back from a south-facing window or near a west or north-facing window.
Check to make sure that your orchids’ planting medium has not dried out in the hot, direct sunlight. Water as needed.
You will not be able to return the yellowed leaves to their former state, but you should be able to save your plants’ life if it is sunburned.
Trim away the sunburned foliage to encourage new leaves to grow.
#2 – Extremes in Temperature:
Check the ambient temperature. Orchids need daytime temperatures ranging from 65° to 80° degrees Fahrenheit. At night, the temperature should not drop below 60° degrees Fahrenheit.
Protect your orchid from sudden temperature changes and from excessively cold or excessively hot drafts.
Remember that orchids are tropical plants, so they like warm temperatures and high humidity.
#3 – Too Little Water:
Droopy leaves that are wrinkly and yellow indicate that your plant is thirsty. In general, Phalaenopsis orchid needs a weekly soaking in clean water for twenty minutes. Remove the orchid from the water and allow excess water to drain off.
Alternately, you can simply run water through your orchids’ planting medium.
You’ll do far less harm to your orchid by under watering than overwatering.
If you under-water, you can correct the problem with more water. Overwatering can cause chronic problems that will take time and effort to resolve.
#4 – Crown, Root or Stem Rot:
Excessive watering, overhead watering, or allowing the orchid to stand in water for extended periods of time can cause crown, root or stem rot.
Early symptoms of any of these conditions may include yellow leaves, but if left untreated, the plants’ leaves, stems and/or roots will turn black.
Crown rot is caused by water standing on the leaves or becoming trapped in the crevices between the plant’s leaves. You can avoid this by avoiding overhead watering and by making sure to wipe off any droplets that might happen to come in contact with the leaves.
Stem rot happens when the plant’s stem stays in constant contact with a wet planting medium. To avoid this, do not plant your Phalaenopsis deep in the planting medium and avoid overwatering.
Root rot happens when your plant stands in wet, soggy planting medium for an extended period of time. To avoid this, don’t water your plant too often. Do not allow the plant to stand in water for longer than half an hour.
If your plant does have root rot, you may be able to save it. Examine the roots. If there are some healthy green roots, trim away the bad ones.
Wash the plant with luke warm, running water. You may wish to spray the roots with a 3% percent hydrogen peroxide solution. Allow the plant to sit for a few minutes and then rinse.
With Phalaenopsis orchids, you can keep your plant as an air plant for a month.
Place or hang it in an area with bright, indirect sunlight and good air circulation around the roots and foliage. Soak it in clean water on a weekly basis until you begin to see healthy, new growth.
At this point, you can repot in a good Phalaenopsis orchid medium. Be careful not to overwater in future.
Before watering, check the planting medium to make sure it is not wet from prior watering. If the top inch is dry, you can water your orchid. Be sure that the container your plant is in has good drainage, and allow excess moisture to run off.
#5 – Bacteria Or Fungus:
Excessive moisture, poor ventilation and overwatering can cause problems with fungal infections and bacterial disease.
If the undersides of your plants’ leaves begin to turn yellow, it can be an indication that it is infected with fungus or bacteria. Infected leaves will turn black, become slippery, and begin to smell bad.
Be sure to quarantine infected plants so that fungus and bacteria do not spread to your other plants. Treat as you would root rot.
Remove all affected parts of the plant, rinse the plant and treat with a 3% hydrogen peroxide. Keep your ailing Phal as an air plant until you see new growth. Replant into fresh medium.
#6 – Nutritional Deficiencies:
Orchids that are low in nitrogen and magnesium have trouble producing chlorophyll, the green pigment that gives all plants their color. The first sign of a plant low in these nutrients, is yellowing leaves.
If your orchids’ leaves begin to yellow around the tips and the sides, this is a sure sign that your plant is low in nitrogen and/or magnesium.
To avoid this problem, choose a high quality orchid fertilizer that contains a good balance of nutrients, micronutrients and trace elements. Apply on a regular basis according to packaging instructions.
#7 – Pests:
Yellowing leaves can be a sign of an advanced infestation of pests such as:
- False Spider Mites
- White Mealybugs (Learn more Controlling Mealybugs On Orchids)
- Red Spider Mites
- Thrips
- Plant Scale
All of these pests attack your orchid by sucking its juices out. They all reproduce and spread fast wreaking havoc throughout your houseplants if you are not vigilant.
Related: Is Insecticidal Soap Safe For Orchids?
Examine all of your houseplants. Use a bright light and a magnifying glass to be certain of catching any pests early. Many can be dealt with by wiping them off and/or giving your plant a good hard blast with water. Be sure to isolate any affected plants from unaffected plants to prevent spread.
Advanced infestations can be dealt with by spraying with a neem oil insecticide, insecticidal soap mixtures, and/or dilutions of isopropyl alcohol. If these don’t work, break out the big guns and use a mild solution of pyrethrum bug spray.
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Yellowing Leaves are Common Among All Types of Orchids
This article has focused on the yellowing of leaves in Phalaenopsis orchids. The information provided can be generalized to other types of orchids.