Written by Ivy
Feb 10 2023
Hibiscus leaves turn yellow as a sign of stress due to drought, over watering, a deficit of nutrients or as a reaction to too much phosphorous in the soil. In response to a sudden drop in temperature, the leaves of tropical hibiscus species turn yellow. Insufficient lighting can cause hibiscus leaves to turn yellow. Hibiscus leaves may also turn yellow due to either too much or not enough water.
Keep reading to find out why your hibiscus leaves have turned yellow and how to revive it…
While yellow variegation on leaves can be good with some plants, the plant is trying to tell you something if your hibiscus is developing yellow leaves. It is indicating that a particular need needs to be met. To prevent issues from getting worse, become familiar with the main causes of yellowing hibiscus leaves.
Since hibiscus plants are native to tropical regions with heavy rainfall, they prefer consistently moist soil. The leaves will shrivel, turn yellow, and curl downward when they are under drought stress. The leaves may become dry, brown, and brittle in extreme drought stress, falling off the plant.
Lack of frequent plant watering is a common cause of drought stress. They require additional water as soon as the soil's surface begins to dry out. But it can also happen when plants are grown in quickly draining rocky or sandy soils or when strong winds remove water from the leaves.
The second most frequent cause of yellow leaves on your plant(s) after underwatering is overwatering. Plants appreciate moist soils, but if you continuously saturate the ground, it creates boggy conditions that deprive the roots of oxygen. This oxygen deficiency eventually suffocates the roots and turns the leaves yellow.
In contrast to underwatering, overwatering causes the leaves to droop and possibly become mushy rather than appear shriveled.
Overwatering is typically related to giving plants too much water too frequently, but it can also be related to soils with slow drainage. Soils high in clay or heavily compacted drain too slowly for hibiscus plants. Instead of soaking into the soil profile, water collects around the roots.
A nutrient deficiency is a typical reason for yellowing leaves, regardless of the type of plant. Plants need certain "essential" nutrients to grow and thrive. If they don't get enough of these nutrients, they'll show signs of deficiency. When nitrogen, iron, manganese, or zinc levels are too low in hibiscus plants, the result is persistently yellow leaves.
The soil's low fertility (for example) causes nutrient deficiencies., sandy soils don't retain nutrients as silt or clays do), overwatering pushes nutrients out of the root zone, or soil chemistry makes them unavailable for plant uptake. Given that many symptoms are similar, it can be challenging to identify which nutrient is deficient. However, a crucial clue is whether the yellowing appears on older or new leaves.
The soil can be made more fertile and given the ability to naturally retain nutrients by adding organic materials. If you decide to use conventional fertilizers, apply a half dose every two weeks from when plants begin to grow in the spring until the flowers stop blooming for the year.
Your hibiscus' yellowing leaves may also be due to nutrient toxicity. Consequently, the difficulty of troubleshooting the issue is only increased. Compared to other plants, hibiscus are more sensitive to high soil phosphorus levels. But the issue isn't with the phosphorus (P) per se; rather, the yellowing is a result of the deficiency of other nutrients brought on by the accumulation of phosphorus in the soil.
Even though iron and zinc are present in adequate amounts, hibiscus plants naturally absorb more of this nutrient when phosphorous levels are too high.
Too much soil P is usually due to over-fertilization, mainly by applying products marketed as bloom boosters with higher phosphorus levels. If you believe this to be the reason for your leaves turning yellow, cut back on fertilizer use temporarily and keep the plant receiving regular waterings.
Nutrient availability and soil pH are closely related. It affects the nutrients that are available for the roots to absorb when soils are too acidic or too alkaline, and deficiencies result. As was already mentioned, a lack of nitrogen, iron, zinc, and sulfur causes the yellowing of leaves.
For the best nutrient availability, hibiscus should be planted in slightly acidic soil with a pH of 6 to 7. The soil pH can be altered if it is significantly out of range due to various factors, such as the parent material of the soil and the amount of rainfall.
You'll notice that your plant's lovely green leaves start to turn yellow if it doesn't get enough sunlight. Hibiscus plants require at least eight hours of sunlight each day. Low light levels cause photosynthesis to slow down because less glucose is formed. Plants produce less chlorophyll and their leaves lose their green color as a result of having less energy stored in the cells for other processes.
Remember that hibiscus grows seasonally in the spring, summer, and fall before going dormant in the winter. Your plant may begin to naturally get ready for winter dormancy as autumn progresses. It draws inspiration from the shorter days and cooler weather. You'll see leaves begin to yellow, and they may even fall from the plant.
Chemical shock is not a frequent issue, but it can occur with your hibiscus plant. Using too many pesticides or the incorrect pesticide for your Hibiscus plant can cause chemical shock in the plants.
As an alternative, spraying the plant with a pesticide in the middle of the day while it is being scorched by the sun can cause chemical shock and cause the plant's leaves to turn yellow. Therefore, if you recently used pesticide on your hibiscus plant, that could be the reason.
But if you used the correct dosage and the right pesticide and sprayed the plant in the morning, then the leaves turning yellow are probably caused by something else on this list.
Another reason for yellow leaves on a hibiscus plant is an unexpected, abnormal drop in temperature. Only zones 9 to 11 are suitable for growing tropical varieties because they are cold-sensitive. Hardy types can tolerate colder weather but are still vulnerable to cold shock. If temperatures fall too low, both types of chlorophyll decompose or their synthesis stops.
Hibiscus are known for being reasonably pest-resistant, but they are susceptible to infestations of spider mites. The yellow spots are caused when they feed on the plant's leaves by puncturing the cuticle and sucking the nutrient-rich sap. The entire leaf appears yellow when there is a severe infestation because the yellow dots merge into a large mass.
Like all plants, hibiscus plants experience active and passive growth phases. For the Hibiscus plant, the active growing period is in the spring, summer, and fall months.
The hibiscus plant will begin to enter its dormant stage at the end of autumn, when the seasons start to change. When the plant starts to go dormant, its leaves will start turning yellow, and they will eventually fall off the plant.
Reduce the amount of water you are giving your hibiscus plant during this period as the plant goes dormant and let it rest for the winter.
Minerals that are dissolved in hard water can harm a variety of plants, including hibiscus. There are many different minerals that can be found in hard water, but calcium and magnesium are the most frequent ones. These minerals are typically present in high concentrations, which can be extremely harmful to your hibiscus plants.
The first problem is that hard water can result in the formation of mineral deposits in the soil or on the soil's surface. These buildups may hinder the penetration of nutrients into your soil and obstruct their uptake by plant roots. Due to a lack of nutrients, your plant may experience yellowing leaves. This will prevent it from growing healthily. Furthermore, these deposits can obstruct proper drainage, preventing water from penetrating the soil as nature intended and staying on top of the soil instead.
Beautiful flowering shrubs called hibiscus plants come in a variety of hues. There are red, pink, and purple varieties, so they make great accent plants in any garden. However, if you notice your hibiscus leaves have turned yellow, you may have cause for concern.
Once you've sleuthed out the cause of the problem, here are some tips for getting your plant back on track:
There are several causes that you can look into if your Hibiscus plant's leaves are turning yellow. Some of the causes are natural, so you don't need to worry about them. However, some of the causes should really worry you because they have the potential to kill your hibiscus plant.
The best way to determine the correct diagnosis is to go through the list one at a time, determine which causes apply to you, and then address each one one at a time. Wishing you luck with your hibiscus plant!