Plumeria leaves turn yellow due to stress, which can be caused by a multitude of reasons.
The most common causes are overwatering, underwatering, too much sunlight, not enough sunlight, pests, disease, depleted soil, temperature changes and natural aging.
This article will discuss the causes of yellowing plumeria leaves and how to remedy each one.
Why are my plumeria leaves turning yellow?
Overwatering
Plumerias want their soil moist, but they can actually tolerate dry spells for a certain amount of time. They can become overwatered if you give them too much water and the soil is perpetually soggy. An overwatered plumeria plant’s leaves can become yellow. Overwatering can also lead to root rot, which happens when the plant’s roots are soaked in boggy soil, limiting their oxygen intake. The plant is unable to respire, leading to the roots dying and rotting.
You can remedy overwatering by skipping a week of watering so that the soil and the roots are given time to dry. If you are able to catch the overwatering in its early stages, your plant can make a full recovery.
You can help dry out the soil quickly by exposing it to the sun or a source of bright light.
You can also help with the excess water by making sure the pot has drainage holes at the bottom. Transfer the plant to a new pot with drainage holes and use new, well-draining soil.
Underwatering
Another reason plumeria leaves turn yellow is underwatering. The plant can become stressed if it does not get an adequate amount of water. Not only will the plant not be able to absorb water, but the transport of essential nutrients will also be affected. The roots will also be forced to exert extra effort in searching for water nearby, adding to the stress.
You can remedy underwatering by watering the soil until it is soaked. Keep pouring until you can see the excess water flowing from the drainage holes at the bottom of the pot.
Place the plant in a partially shaded location so that its transpiration rate will slow down. This will help avoid rapid moisture loss for the plant.
If you suspect you have not been giving your plant enough water, you need to compensate by increasing the watering frequency. If you were watering it every five days, try watering it every four days and see if that fixes the problem.
Too much sunlight
Plumeria typically has no problem growing in different light conditions, be it partial shade, partial sun or full sun. Even those that are grown indoors will get used to being in the shade. But if you suddenly move a plant that has grown indoors into full sunlight, it will suffer. The light can cause sun damage, including yellowing and browning of the leaves.
You can remedy this by taking the plant indoors to avoid further sun damage. You can try to help the plant adapt to sunlight by gradually introducing it to more and more light every week.
You can also just expose the plant to morning light and take it back into the shade in the afternoon. Morning sunlight is less destructive than afternoon sunlight.
If you cannot move the plumeria indoors, you can protect it by placing more sunlight-tolerant plants around it.
Not enough sunlight
Lack of exposure to light can also contribute to the yellowing of your plumeria leaves. This is not only because it causes stress, but it will also reduce the plant’s ability to photosynthesize. If its photosynthesis is compromised, it will not have sufficient food and will lose much of its vigor. The plant can also become leggy in pursuit of the closest light source.
Remedy this by transferring the plant to a spot that exposes it to more sunlight. Place it under the morning sun, but take it back in in the afternoon so that it does not scorch.
In seasons when there is little sunlight each day, you may need to provide the plant with alternative sources of light. Buy a grow lamp to use on your plant during the winter.
Pests
Insects can be sneaky when attacking your plant, and it might take weeks before you even notice that they are there. Plumeria is usually hardy against pests, but it is still vulnerable and its leaves can turn yellow because of them.
The most common pests found on plumeria are scale insects, thrips, whiteflies and mites.
Scale insects will insert their mouthparts into the plant and suck the sap from the tissue. This will cause the leaves to turn yellow and the plant to look water-stressed and stunted.
Thrips will puncture the plant tissues and also feed on its contents. They will leave silver leaf surfaces and brown spots.
Whiteflies pierce the plant’s phloem with their mouthparts and suck the sap, causing the leaves to turn yellow and fall off.
Mites will suck on the leaves’ contents and turn the leaves yellow and red.
You can eradicate these pests by using an insecticide.
Disease
One of the most common fungal diseases to affect plumeria plants is plumeria rust, caused by Coleosporium plumeriae. The fungus creates a yellow or yellow-orange appearance on the upper side of the leaves. It will also cause lesions and a sunken appearance on the leaves. Eventually, the leaves will curl and drop off.
You can get rid of the disease by removing all the infected leaves and destroying them. Make sure the infected plant is kept away from your other healthy plants so that it does not spread.
Apply a fungicide that is specially designed for this type of fungus.
Depleted soil
Another cause for plumeria leaves turning yellow is depleted soil. Soil becomes depleted when its nutrient level decreases, which can be caused by normal watering. The nutrients will be washed away sooner or later.
You can remedy this by repotting the plumeria. Replace the old soil with fresh soil that is full of nutrients. You can do this once a year or whenever the plant looks too big for its pot.
Temperature changes
This plant does not like the cold. It cannot stand temperatures lower than 40 degrees Fahrenheit. If exposed to extremely cold weather, the tissues become damaged and the leaves will turn yellow. Even getting hit by an air conditioner can have an effect on the plant.
Remedy this by taking the plant indoors during the winter, or whenever the outside temperature reaches below 40 degrees Fahrenheit.
If you cannot bring the plant indoors, insulate it using cotton sheets.
If there are cold drafts reaching your plant indoors, transfer it to a different part of your house where the room temperature is more stable.
Natural aging
When plumeria leaves become old, they will naturally turn yellow. This is not a cause for concern because it is a completely normal process.
You can remove the yellow leaves to preserve the plant’s aesthetic. Simply pluck them out at the base.
Conclusion
Yellowing plumeria leaves is usually a sign of stress, meaning a stressor needs to be identified, or there are aspects of its living conditions that are not ideal. Yellowing leaves can also just be part of the plant’s natural aging process.
The most common causes of yellowing plumeria leaves are overwatering, underwatering, too much sunlight, not enough sunlight, pests, disease, depleted soil, temperature changes and natural aging.
As long as you provide all of a plumeria’s basic needs, you will not have any problem growing it in your garden.
Image: istockphoto.com / Fahroni