Desert Rose plants (Adenium obesum) can develop yellow leaves for several reasons. Some are as simple and benign as a change of seasons.
Desert Rose plants’ leaves may turn yellow in the fall. Poor conditions can also cause yellowing leaves.
For example:
- Too much water
- Too little water
- Too little light
- Fungal infection
- Pest infestation
… All may cause yellowing leaves.
Leaves Yellow On Adeniums Due To Seasonal Change
Desert Rose is a tropical, evergreen, and succulent plant. It is only winter hardy in USDA hardiness zones 10 through 12. For this reason, it is usually kept as a houseplant.
When grown outdoors or in a very cool setting indoors, the plants’ leaves may turn yellow with leaf drops in autumn. This signals a transition into a dormant state.
High humidity (especially with low air circulation) can sometimes cause some spotting on the desert rose leaves.
The best way to fix leaf spot diseases caused by bacteria or fungi is to report the affected adenium plant in fresh soil and pot.
You choose whether to overwinter the Desert Rose as an active houseplant or allow it to go into dormancy.
If the plant is in a small pot, bring it in before the weather turns cold to prevent yellowing and dropping leaves. Yellowing of the leaves is caused in the early stages, and then they develop black spots and splotches and fall off.
Choose to keep the plant in dormancy through the winter. Reduce watering and keep the soil dry for a period of 3 to 4 months (typically between October and February).
Keep plants in a cool (55° to 60° degrees Fahrenheit) low-light setting during the dormant season. Move it to a brighter, warmer setting in the springtime and give it a feeding. It will begin to produce new leaves shortly.
Overwatering
True to its name, Desert Rose is a plant that does best in an arid environment. During the growing season, use the soak-and-dry method of watering.
Water thoroughly and wait until the top 2″ inches of soil are almost completely dry. Then provide another thorough watering.
They can be watered on a regular basis during the spring and summer, but the water needs to dry out between waterings.
During the plants’ dormant season, sharply reduce watering. Move large, outdoor container plants to a location away from any natural rain. The plants should glean enough moisture from the air from doing well during the dormant period.
Water smaller indoor plants no more often than once a month during the dormant period.
Related: Tips on Desert Rose Watering
Under Watering
During the plant’s growing season, provide thorough watering whenever needed. They do not need or want to stand in water, so it is far better on the side of underwatering when it comes to watering.
If your Desert Rose stays dry for an extended period, the result is yellowing starts, followed by dropping leaves. This is called drought stress.
Desert rose is an ornamental succulent garden plant that is known for its swollen or caudex trunk. It can store moisture in its swollen trunk to use at times of drought.
Wrong Soil
Even if you reduce watering, a Desert Rose can suffer from too much water if not planted in good potting soil.
These desert plants do well with sharply draining, gritty, sandy soil. Use a potting mixture recommended for cactus and succulents and a pot with drainage holes.
Related: Best Potting Mix For Desert Rose
Nutrient Deficiencies
Although Desert Rose is not a heavy feeder, it does need some nutrition. During the growing season, fertilize weakly – weekly.
Sometimes roses don’t get enough of certain nutrients, such as iron, magnesium, and nitrogen. Lack of nutrients can lead to chlorosis. If you think this is the problem, do a pH soil test to see whether you should add amendments.
Give the plant a half-strength dose of balanced 20 – 20 – 20 liquid fertilizer once a week. Stop fertilizing during the winter months.
Related: Fertilizer for Desert Rose
Low Light
All plants need sunlight to produce chlorophyll and grow green leaves. Keep your Desert Rose plant in a low-light setting during the dormant period. Move the plants to a bright sunny spot during the growing period.
Remember, this plant needs a hot, dry setting to survive, thrive, produce flower buds and bloom.
Fungus
Overwatering, overcrowding, and too little light can result in a fungal infection:
- Root Rot
- Stem Rot
- Leaf Rot
Brown, rusty spots on the leaves. Dark, soft spots on the trunk. A general listlessness along with yellowing, falling leaves often say rot.
If you suspect fungal diseases, isolate the plant from other plants or move your plants somewhere drier & with enough sunlight. Others use a fungicide to kill the fungi.
Give the Desert Rose:
- Good lighting
- Ample spacing
- Air circulation
- Withhold water until the soil is completely dry
Prune away leaves and stems that exhibit fungal infection symptoms.
To prevent the spreading of fungus:
- Use a sterilized cutting tool
- Wipe the blade with isopropyl alcohol between cuts.
While the plant recuperates, spray it weekly with a fungicidal mixture, such as a Neem oil spray.
Mix a couple of tablespoons of neem oil with a gallon of water for an effective, natural treatment.
If the plant needs repotting, use clean, new soil along with a new, clean (or sterilized) container.
When repotting, examine the roots. Trim away any soft, mushy roots with a sterilized, sharp cutting tool. Keep the potting medium damp but not wet, and allow plenty of air circulation around the seed-raising containers.
Pests
The same poor conditions that result in fungal infection cause Desert Rose to become subject to pest infestation.
Common houseplant pests such as:
- Mealybugs
- Aphids
- Spider mites
- Thrips
… take up residence on weakened plants.
Related: Getting Rid Of Desert Rose Aphids | Adenium Pests and Diseases
Deal with these insects as you would treat fungal infections.
Spray a Neem oil mixture on the pests. Or mix up a solution of insecticidal soap at a rate of 5 tablespoons to 1 gallon of water. Spray every other week.
Leaves turning yellow on Desert Roses is not the end of the world. Review the steps to determine your next action.