Hibiscus is a beautiful flowering plant that comes in many colors and varieties. It is popular for its showy blooms that attract hummingbirds, butterflies, and bees. Hibiscus can be grown indoors or outdoors, depending on the climate and type of plant.
However, like any other plant, hibiscus can have some problems that affect its health and appearance. One of the most common issues that many gardeners face is yellow leaves on their hibiscuses. This can be a sign of stress, disease, or environmental factors that need to be addressed.
In this article, we will explore the main causes of yellow leaves on hibiscuses and how you can prevent and fix them.
Overwatering Or Underwatering
One of the most common reasons why your hibiscuses’ leaves turn yellow is improper watering. Too much water or not enough water can both stress out your plant and cause its leaves to lose their green color.
How do you know if you are overwatering or underwatering your plant? Here are some clues:
- If you are overwatering your plant, you may notice that the soil is always wet or soggy, that there are signs of mold or fungus on the surface, that the roots are rotting or smelly, that the leaves are wilting or drooping, and that they turn yellow from the bottom up.
- If you are underwatering your plant, you may notice that the soil is always dry or hard, that there are cracks on the surface, that the roots are shriveled or brittle, that the leaves are crispy or curled up at the edges, and that they turn yellow from the top down.
To avoid overwatering or underwatering your plant, you need to water it properly according to its needs. Here are some tips:
- Use a well-draining potting mix for your container-grown plants. Avoid using soil that retains too much moisture or drains too quickly.
- Check the soil moisture before watering by inserting a finger into it. If it feels moist up to an inch deep (or two inches for larger pots), then wait until it dries out slightly before watering again. If it feels dry below an inch deep (or two inches for larger pots), then water thoroughly until water runs out of drainage holes.
- Water less frequently during winter when growth slows down than during summer when growth speeds up.
- Water more often during hot weather when evaporation increases than during cool weather when evaporation decreases.
- Water early in morning when temperatures are lower than later in day when temperatures are higher.
Nutrient Deficiency Or Excess
Another reason why your plants’ leaves turn yellow is nutrient imbalance. This means either they lack certain nutrients they need for healthy growth (deficiency) or they have too much of certain nutrients they don’t need for healthy growth (excess).
How do you know if your plant has a nutrient problem? Here are some clues:
- If your plant has a nitrogen deficiency, you may notice that the leaves turn pale green or yellow, especially on older leaves. The plant may also have stunted growth and poor flowering.
- If your plant has a phosphorus deficiency, you may notice that the leaves turn dark green or purple, especially on older leaves. The plant may also have weak stems and roots and poor flowering.
- If your plant has a potassium deficiency, you may notice that the leaves turn yellow or brown at the edges and tips, especially on older leaves. The plant may also have wilting, curling, or drooping leaves and poor flowering.
- If your plant has an iron deficiency, you may notice that the leaves turn yellow with green veins, especially on younger leaves. The plant may also have reduced growth and chlorosis (loss of chlorophyll).
- If your plant has a magnesium deficiency, you may notice that the leaves turn yellow with green veins, especially on older leaves. The plant may also have interveinal chlorosis (yellowing between veins) and leaf curling.
- If your plant has an excess of phosphorus, you may notice that the leaves turn dark green or blue-green with purple spots or streaks. The plant may also have reduced growth and flowering and increased susceptibility to diseases.
- If your plant has an excess of salt or chemicals, you may notice that the leaves turn yellow or brown at the edges and tips. The plant may also have leaf scorching (burning), wilting, dropping of buds and flowers.
To fix nutrient problems in your hibiscus plants, you need to fertilize them properly according to their needs. Here are some tips:
- Use a balanced fertilizer for hibiscus plants that contains nitrogen (N), phosphorus (P), potassium (K), and micronutrients such as iron (Fe), magnesium (Mg), zinc (Zn), etc. A good ratio is 10-4-12 or 9-3-13 for N-P-K.
- Fertilize your hibiscus plants once a month during spring and summer when they are actively growing and blooming. Reduce fertilizing to once every two months during fall and winter when they are dormant or slow-growing.
- Apply fertilizer according to the label instructions. Do not overfertilize as this can cause more harm than good. Less is more when it comes to fertilizing hibiscus plants.
- Water your hibiscus plants well before and after fertilizing to prevent root burn and salt buildup in the soil.
- Use organic fertilizers such as compost, manure, worm castings, etc., instead of chemical fertilizers whenever possible. Organic fertilizers are more gentle on plants and soil life than chemical fertilizers.
Another factor that can cause yellow leaves on hibiscus plants is sunlight exposure. Hibiscus plants need plenty of sunlight to thrive but not too much that it can damage them.
How much sunlight does your hibiscus need? Here are some clues:
- Hibiscus plants need at least 6 hours of direct sunlight daily to bloom well. However, this is the bare minimum. Hibiscus plants grow best when they receive 8 hours of sunlight.
- Hibiscus plants can also grow with as little as 2 hours of direct light as long as they also receive 6–8 hours of indirect light daily. However, they won’t fill in as fully or bloom as spectacularly as those in full sun.
- Hibiscus plants can tolerate some shade, especially during the hottest part of the day, but they don’t like deep shade or too much shade. Too little sunlight can cause yellow leaves, poor flowering, and leggy growth.
- Hibiscus plants can also suffer from too much sunlight, especially if they are not watered enough or acclimated properly. Too much sunlight can cause sunburned leaves, wilting, drooping, and stress.
To fix sunlight problems in your hibiscus plants, you need to provide them with the right amount and intensity of light according to their needs. Here are some tips:
- Choose a sunny spot for your hibiscus plants that receives at least 6 hours of direct sun per day. If possible, aim for 8 hours of sun for optimal growth and flowering.
- If you live in a hot climate where the sun is very intense, you may want to provide some afternoon shade for your hibiscus plants to prevent them from overheating or burning. You can use a shade cloth, an umbrella, a pergola, or other structures to create some shade.
- If you live in a cold climate where the sun is weak or scarce, you may want to supplement your hibiscus plants with artificial light during winter or cloudy days. You can use a grow light, a fluorescent lamp, or an LED bulb to provide some extra light for your hibiscus plants.
Another possible cause of yellow leaves on hibiscus plants is pest infestations. Hibiscus plants can attract various insects that feed on their sap, foliage, buds, and flowers. These pests can damage the plant’s health and appearance, and also transmit diseases and viruses.
Some of the common pests that attack hibiscus plants are:
- Aphids: These are tiny insects that enjoy feeding on hibiscus juices, and they prefer stems and flower buds. They can cause leaves to curl, wilt, or turn yellow. They can also secrete a sticky substance called honeydew that attracts ants and fungal growth.
- Spider mites: These are microscopic creatures that suck the sap from the undersides of leaves. They can cause leaves to turn yellow, brown, or grayish with tiny dots or webs. They thrive in hot and dry conditions and can multiply rapidly.
- Whiteflies: These are small white insects that fly around when disturbed. They feed on the sap of leaves and buds and can cause yellowing, wilting, or dropping of leaves. They also secrete honeydew that can lead to sooty mold growth.
- Thrips: These are slender insects that feed on flower buds and petals. They can cause bud drop, distorted flowers, or brown spots on petals. They can also spread viruses such as hibiscus chlorotic ringspot virus (HCRV) that causes yellow rings or spots on leaves.
- Mealybugs: These are soft-bodied insects covered with white waxy filaments. They feed on stems, leaves, buds, and roots and can cause stunted growth, yellowing, or curling of leaves. They also secrete honeydew that attracts ants and fungal growth.
Other pests that may affect hibiscus plants include scales, gall midge, Japanese beetles, etc.
To prevent and treat pest problems on your hibiscus plants:
- Inspect your plants regularly for signs of pests or damage. Look for holes, spots, webs,
curling, wilting, or dropping of leaves or buds or flowers or stems or roots or any unusual growths or discolorations on your plants.
- Remove any infected or damaged parts of your plants with clean scissors or pruners. Dispose of them properly to avoid spreading pests or diseases to other plants.
- Wash your plants with a strong spray of water to dislodge any pests or eggs from their surfaces. Do this early in the morning or late in the evening to avoid sunburning your plants.
- Use natural remedies such as insecticidal soap, rubbing alcohol, neem oil, etc., to kill or repel pests from your plants. Follow the instructions on how to apply these products safely and effectively.
- Use chemical pesticides only as a last resort if natural remedies fail to control pest infestations. Choose pesticides that are labeled for use on hibiscus plants and follow the directions carefully. Avoid spraying pesticides when bees or other beneficial insects are active.
Yellow leaves on hibiscus plants can be caused by various factors such as nutrient problems, sunlight exposure, and watering issues. To prevent and fix these problems, you need to provide your hibiscus plants with proper care and maintenance according to their needs.
Hibiscus plants are beautiful tropical flowers that can brighten up any garden or home with their colorful blooms. By following these tips on how to deal with yellow leaves on hibiscus plants, you can ensure that your hibiscus plants stay healthy and happy all year round.