10 Causes of Yellow Hibiscus Leaves—and the Quickest Ways to Fix Them

Few things are more beautiful than a thriving hibiscus in full bloom, with its bold, tropical flowers and lush green leaves. So it can be disappointing when the foliage starts to lose its color, fading to a sad yellow that can become an eyesore in the garden. While yellowing leaves can be a sign of natural aging, they can also signal that something is wrong with your plant. From overwatering to fungal diseases, these are the most common reasons hibiscus leaves turn yellow, plus expert tips for fixing each problem.

Inadequate Water

Hibiscus plants need consistently moist, but not waterlogged soil to thrive. "Dehydration causes the leaves to yellow and then brown," says Linda Langelo, horticulture specialist at Colorado State University Extension. "When the soil lacks sufficient water for the roots to absorb, the tissues in the leaves turn yellow and brown." To fix this, aim to give your hibiscus plants 1 to 2 inches of water per week, or when the top inch of soil feels dry.

Poor Soil Drainage

Although hibiscus plants prefer consistent moisture, the roots hate sitting in water. "Poor drainage leads to root rot and suffocation, turning leaves yellow from the bottom," says Kelly Funk, president and CEO of Jackson & Perkins. Always plant hibiscus in well-draining soil, and plant potted hibiscus in a container with drainage holes. If your soil is clay-based or slow-draining, amend it with organic matter or perlite. 

Inadequate Sun

As a tropical plant, hibiscus is a sun lover that needs six to eight hours of direct sunlight daily. "Low light slows photosynthesis, causing pale or yellow leaves," says Funk. If your plants are in a low-light area of your garden, transplant them in the fall or prune surrounding vegetation to increase sunlight. If you're growing potted hibiscus, move them to a brighter area.

Age

Sometimes, yellowing leaves on plants is unavoidable. "It's natural for older leaves, especially at the base, to yellow and fall off as the plant grows," says Funk. If this is the cause, Langelo notes that there is no remedy. "It is a natural process. Every plant has its maturity," she says.

Root Damage

Hibiscus plants can suffer from root damage for various reasons. "Transplanting, digging near roots, or compacted soil can damage the roots, impeding nutrient and water uptake and causing yellowing leaves," says Funk. To fix this, she recommends transplanting or repotting the hibiscus. Trim the damaged roots, apply a root stimulant if needed, and replant. Water well and keep the plant temporarily shaded.

Improper Soil pH

Hibiscus prefers slightly acidic soil with a pH range between 6.0 and 7.0. "Alkaline soils lock up nutrients like iron, leading to yellowing between leaf veins," says Funk. She recommends testing your soil pH and amending alkaline soil with elemental sulfur. If your soil is too acidic, Langelo recommends adding calcium carbonate. 

Irregular Temperature

Hibiscus plants are sensitive to sudden drops in temperature, drafts, or heatwaves. These fluctuations can interrupt normal growth cycles and cause yellowing. Ensure you know the ideal temperature range for hibiscus and regulate it to the best of your ability.

Lack of Nutrients

As heavy feeders, hibiscus plants need enough nutrients to provide healthy foliage. According to Langelo, a lack of nutrients, especially nitrogen, causes hibiscus leaves to turn from green to yellow. To remedy this issue, Funk recommends feeding your plants with a balanced, water-soluble fertilizer. "For micronutrient deficiencies, apply chelated iron or foliar sprays," she adds. That said, be careful not to overfeed your soil, as this can block the roots from absorbing water.

Disease

Fungal diseases can turn hibiscus leaves yellow, as the fungus interferes with the plant’s chlorophyll production, says Langelo. To prevent fungal infections, water at the base of the plant and ensure it has proper air circulation. If your plant already has a fungal infection, Funk recommends removing infected leaves and applying a fungicide.

Pests

Sap-sucking pests like aphids, whiteflies, and spider mites can cause yellow dots to form on leaves. To treat these insects, Langelo recommends rubbing the leaves with insecticidal soap or neem oil to get rid of the pests.