Elephant ear plants, Colocasia sp., are tropical perennials that have gorgeous large heart-shaped leaves that stand tall on herbaceous stems and are wonderful houseplants for beginner gardeners.
These easy-growing beauties gain height quickly and with enough space can reach 6 feet tall within a few short months.
Grown from large tubers, elephant ear plants get stronger each year, with healthy plants living almost a decade. So, if yours starts to turn yellow, you should act rapidly to determine the cause, or else your beloved plants could quickly perish.
From soil issues to pest problems, this article describes the top 10 reasons your elephant ear plants’ leaves are turning yellowing and how to fix it.
Why Do Elephant Ear Plant Leaves Turn Yellow
The yellowing of leaves is called chlorosis and occurs when environmental factors disrupt the plant’s ability to produce sufficient chlorophyll.
If you’re wondering, chlorophyll is the microscopic leaf structure that houses photosynthesis and is responsible for the leaf’s green color.
Causes of Yellow Leaves
The most common causes of elephant ear leave turning yellow are issues with watering schedules, nutrient deficiencies, over-fertilizing, improper soil pH, low humidity, excessive sunlight, temperature fluctuations, natural succession, pests, and disease.
Time to break those reasons down now, and provide you with what each might look like in your plant and what you can do to fix or prevent it.
1. Watering Problems
The top cause of yellowing leaves on elephant ear plants is watering issues. These tropical plants prefer consistently moist soil that doesn’t experience periods of drought.
Elephant ear plants will often need to be watered daily, especially when grown in smaller containers. But never leave it in standing water and saturated soil for too long or else leaf yellowing and severe wilting will occur.
If you suspect the soil is becoming frequently saturated, then transplant your plant into potting soil with better drainage. The following mix works well for tropical houseplants:
- 1 part Coco Coir
- 1 Part Perlite
- 1 part Vermiculite
- 1 Part Worm Castings
Letting the soil of your elephant ear plant frequently go dry is a pivotal mistake that ends in yellow leaves, root death, severe stress, and if prolonged, eventually plant death.
If the top of the soil is dry, then your plant needs water. Add enough to soak through to the catch tray.
2. Nutrient Deficiencies
As a large-leaved tropical species, elephant ear plants require a lot of nutrients. Feed yours at least once a month during the growing season to limit the chances of nutrient deficiencies.
I recommend using a water-soluble fertilizer with an NPK ratio of around 5–1–6.
These plants need less phosphorus than nitrogen and potassium because the phosphorus in the soil of their native region often binds to the iron oxides that give that soil its red color, rendering it unavailable and forcing these plants to have evolved to survive on lower amounts of phosphorus.
Test your soil with a handheld soil analyzer to help you determine which nutrients are most lacking. The most likely culprits that affect elephant ear plants are:
Nitrogen is the most likely nutrient to be deficient and is often caused by leaching from heavy watering or unfortified soil.
Chlorosis will begin in the older leaves and will quickly spread if not remedied with a high nitrogen fertilizer supplement or a 50% worm casting top dress.
Iron deficiencies are most often caused by soil that lacks organic matter, or pH imbalances that render the available nutrient unusable. Chlorosis will cover the entire leaf while leaving the veins green.
Potassium deficiencies show signs of yellowing leaf edges and veins that eventually lead to severe leaf curling and loss of all color.
An elephant ear plant with a potassium deficiency is often a result of the plant having previously suffered drought conditions.
Magnesium deficiencies will cause interveinal leaf chlorosis and severely stunted leaf production.
As the deficiency continues, the leaves begin to develop yellowish spots and reddish tips.
High soluble salt toxicity is the most common consequence of over-fertilization and will present similar symptoms as potassium deficiencies with yellowing and curling leaf edges.
If salt toxicity from over-fertilization occurs, flush the soil with fresh water using at least the volume of the container and repeat the irrigation several times.
4. Soil pH
Elephant ear plants prefer a slightly acidic soil pH between 5.5 and 6.5.
When the soil pH is outside of this range, your plants will get yellow leaves from an inability to access nutrients. If left untreated it causes shock, which plants rarely recover from.
Check the soil pH with a handheld meter and adjust the pH accordingly with lime to raise soil pH and Aluminum sulfate can be used to lower (increase acidity).
5. Low Humidity
These large-leaved tropical species prefer a relative humidity near 60%, which is higher than most households naturally produce. If your plant is suffering from low humidity, then use a humidifier or place it in a bathroom with a shower and window.
Low humidity can cause the leaves on elephant ears to be yellow, wilt, and crisp. If caught in time, these plants can easily recover.
6. Excessive Sunlight Exposure
These tropicals are an understory species that prefer bright, indirect sunlight. While not as sensitive as many tropical houseplants, elephant ear plants will get crisp yellow leaves from being sunburnt if they receive several hours of intense direct sunlight.
When grown indoors, they do best in warm, humid rooms with bright south-facing windows that get 6 – 8 hours of indirect sunlight.
7. Rapid or Frequent Temperature Fluctuations
Native to Asian tropical rainforests, Elephant ear plants are accustomed to temperatures that typically don’t drop below 59 degrees Fahrenheit.
If rapid temperature changes occur often, your plant might begin to produce yellowing dead spots followed by unfortunate leaf drops.
Keep your plant in a room with consistent temperatures, away from main doors, and out of rooms with north-facing windows, especially in the winter.
8. Old or Spent Leaves
As elephant ear plants grow new leaves, their old leaves will naturally turn yellow and die. Prune these spent leaves to keep your plant looking fresh and to enable it to focus energy on producing healthy new shoots.
9. Pest Infestation
Spider mites are common household pests that cause tiny yellow dots on the surface of infected leaves.
Treat and prevent spider mites by applying an all-natural essential oil spray that contains neem, lemongrass, and lavender.
Be sure to check and treat any incoming plants from greenhouses that may contain unseen infestations of common household pests before bringing them indoors.
Leaf blight caused by the fungus Phytophthora colocasiae is the most common disease that infects elephant ear plants. Symptoms of leaf blight include the appearance of small, yellow, water-soaked spots that rapidly grow, encompassing the entire plant in 3 – 5 days.
It’s a destructive and deadly fungal infection spread through water droplets during times of high humidity, so try to minimize any accidental splashing while watering.
Because of high fatality rates, prevention is critical. Sanitize pruning equipment, fertilize, and water regularly, and if necessary, treat with a foliar application of a copper-based fungicide.
Click this link for Causes of Fiddle-Leaf Fig Tree Leaves Turning Yellow
FAQ Elephant Ear Plant Turning Yellow
Should I cut off the yellowing leaves on my elephant ear plants?
Yes, you should prune fully yellow leaves that could be draining nutrients from your plants and attracting pests but don’t take more than 1/3 of its leaves at one time as this can cause stress.
Journal of Plant Nutrition – Quantitative determination of NPK uptake requirements of taro (Colocasia esculenta)
Smithsonian Tropical Research Institute – Paradox Explained: Fast growth despite phosphorus limitation
University of Maryland – Fertilizer Toxicity or High Soluble Salts in Indoor Plants
The University of Winsconsin – Using Aluminium Sulphate to increase soil acidity
Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.