What would cause the leaves to turn yellow?
There are many things that will cause this in container. If they are indoors, then chances are the humidity is very low. This will signal them into dormancy. This can also be caused by a lack of nutrients if you do not fertilize at least once per year.
Unfortunately this can also be caused by a lack of light, Too little or too much watering, and many pests. Could you include a picture, some more information about your area, climate zone, etc? Also pictures can help here as well.
Why is my hibiscus a pale yellow green instead of dark lush green? I live in Mesa, AZ and have sandy soil. Also, what ferti;izer do you recommend? Sorry, I don't know how to upload a photo. I could send it from my phone with a number or email.
Hibiscus leaves may turn yellow because of either underwatering or overwatering, as well as several other problems:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/answers-to-what-causes-hibiscus-leaves-turning-yellow.htm
Here is some advice on fertilizing hibiscus:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-fertilizing.htm
http://www.extension.umn.edu/garden/yard-garden/houseplants/hibiscus/
I've got a hibiscus that's about 4 feet tall that I just started caring for. The leaves are curled down but I see no tiny insects on the leaves. I noticed that the root ball was about 1 inch below the top of the soil. I just removed the soil and am hoping that this helps. Do curled leaves sound like a symptom of the root ball planted too deep?
Many things can cause hibiscus wilting. Recent transplanting, over-watering, under-watering and wilt disease are potential culprits. I don't see much perlite in your potting mix which makes me wonder if your potting mix drains well enough. Soil should be damp, not wet. Fungal disease sets in if roots or trunk stay wet. Water when the soil is dry 1 inch down. Is there a drainage hole in the bottom of your pot?
Hibiscus has white things all over it. I cant see them moving, so I'm not sure if its a bug, but it seems to be multiplying. The plant is beautiful and has new growth and is very full. Dont want to use the wrong thing on it, without knowing what this is.
This could be Thrips, Scale, Mealybug or Whitefly.
Neem Oil is good treatment for most common pests. Neem Oil is organic and safe for people, pets and Bees!
Here are some links with more information.
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-sticky-leaves.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
What do I do about possible root rot?
Make sure the excess water is draining from the soil and container. Soil should be moist, but never soggy.
If you think the root rot is extensive, try lifting the root ball and allowing the soil to dry. Look for mushy and soft roots and prune with a clean garden shear.
Place the plant back into an appropriate sized container, not to large.
Wait and watch for any active growth.
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-container-care.htm
Can a hibiscus tree grow back into a bush plant ?
Yes, with some heavy pruning, this will come back to a bushier form. Just cut down to about a foot from the ground in early spring. Now would be a good time for many areas.
What causes hibiscus leaves to turn yellow?
This depends on if it is in container, outside, your area and climate and MANY other factors. I will need to know a little about all of these to answer your question.