Hidden Valley Hibiscus
Growers & Hybridizers of Exotic, Tropical Hibiscus
Yellow Leaves on Hibiscus
"Help! The leaves on my hibiscus plant are turning yellow. What's wrong with it?"
Don't panic, yellow leaves on hibiscus are normal. They look like something is wrong, but they are usually just a warning, a call for help, and not a sign of impending death.
Hibiscus leaves turn yellow and drop from the plant due to stress. The stress can be of any type, and figuring out what kind of stress is the challenge for the gardener. We cannot tell you exactly what is wrong with the plant without knowing a lot more than you are likely to be able to tell us. YOU have to think about it, and when you are pretty sure you have determined the cause, then you can take action to relieve the stress on your hibiscus. This article is intended to help you figure it out what is wrong.
Stresses that can cause yellow leaves on hibiscus include:
1. Not Enough Water
In warm conditions hibiscus need a lot of water, even every day or more than once a day if it's really hot or windy. Self-watering pots can be an excellent way to avoid this type of stress. A watering system controlled by a timer is another way for gardens with large numbers of plants.
2. Too Much Water
Yes, hibiscus can also be given too much water when the weather is cool or overcast. Hibiscus like to be moist but not sopping wet and if they don't need the water due to cold or dark conditions then too much will stress the root system.
3. Too Hot
This is related to water but please take note on super hot summer days that hibiscus will need lots of water to keep all the big lush leaves well supplied. If they don't get enough they react by dropping leaves (that turn yellow first) so that they don't need as much water.
4. Too Cold
Hibiscus are tropical plants that thrive in the same temperatures that people like, 65-85°F (18-29°C). Like us, they will survive, but they will not like temperatures down to freezing and up to 110°F (38°C). If they get too cold or are placed in a cold drafty window, they can react with yellow leaves.
5. Too Much Direct Sunlight
Hibiscus like sunlight but just as most people like moderate amounts of it so do hibiscus. Too much sun places stress on hibiscus that are not used to it and they can react with yellow leaves or big white spots on leaves. The white spots are similar to sunburn on us. They won't kill the plant but will cause it to shed leaves.
6. Too Little Sunlight
Light is the source of life for plants such as hibiscus. If they do not get enough to support all the big lush leaves they will drop some of their leaves (which turn yellow first) so that they don't need to support so many. However, that means that there is less green chlorophyll left to support the needs of the rest of the plant so it may continue to decline until there are only a few leaves left on the plant.
7. Insects, Particularly Spider Mites
Spider mites are tiny spiders that look like little crabs under magnification. Usually you cannot see spider mites with the naked eye but do they ever leave a mark on hibiscus leaves! First you may see mottling of the leaves which begin to look dirty and then tired. The underside of leaves will show marks made when the mites suck the juices from the leaves. As the infestation gets worse you will see small spider webs under the leaves and at the top of stems. Leaves will yellow and fall off the plant and the entire plant will look stressed. If left untreated, spider mites can cause every leaf on the plant to fall. It takes hibiscus weeks to recover from a bad spider mite infestation so it is best to take action as soon as possible. Click here for complete information on identifying and treating Spider Mites.
8. Too Windy
Most of us do not realize the stress that wind places on plants. Wind dries them out and the result is yellow leaves.
9. Improper Nutrition or pH ~ Chlorosis
This is a different condition, called Chlorosis and the yellow is a different yellow. The leaves will remain partly green and partly yellow when there is a nutrition problem. Leaves almost always fall off the plant after turning solid yellow. If they do not turn completely yellow nor fall off, then it is likely that the problem is a lack of essential nutrients. This can be due to no fertilizer applied or due to a pH level of the soil that is too high or too low. The leaves do not turn a bright yellow all over if this is the case nor do they drop off. Such problems can be corrected by using fertilizer and/or amending the soil with substances that will neutralize the pH. Consult a nursery professional at a local garden center if this is the case. Click here for complete information on identifying and treating Chlorosis.
10. Pesticide Use
This is not a common problem but overuse of pesticide or using the wrong pesticide or too strong a pesticide or spraying in the hot sun of mid day can also cause leaf problems. If you have applied pesticide recently this may be the problem but if you used the same type at the same strength and done so in morning or evening then it is most likely one of the other stress problems above.
Once you have reviewed all the possible problems and decided on a likely source of the stress the cure is to remove the stress. Sometimes it is already done, as when you have watered thoroughly after neglecting to do so during a heat wave. There is no saving the yellow leaves that WILL fall off but the good news is that hibiscus will quickly grow back new green leaves when the stress is removed. Sometimes it becomes necessary to prune back a stem that has lost all of its leaves except for a few at the top. Pruning causes a cascade of plant growth hormones to enter the bare stem and stimulates new growth on the remaining part of the stem after pruning. This is a final solution if all else fails but it is best to remove the cause of stress first and to feed and water the plant well since that may be all it will take to get new growth on your hibiscus.
Yellow leaves are not the worst thing in the world. Sometimes the situation will correct itself, other times you need to correct the stressful condition. The hibiscus will do its part by reacting to the improved condition by no longer dropping leaves and often by regrowing new ones to replace any that were lost. Good luck with your growing and gardening and by all means have fun with it!