I have pruned the hibiscus below the nodes, but left the main stems 12" above the ground level. Will I ever get buds again?
If you have Chinese Hibiscus (Hibiscus rosa-sinensis) you should still get buds again provided that you are meeting the plants' other growing requirements. You'll just have to wait a little longer for them to bloom since you've pruned your hibiscus all the way back to the main stem.
When should you prune a hibiscus?
Waiting till spring is the better option for most types of hibiscus, as explained in this article:
Whether your hibiscus needs pruning at all, and how to care for them during the winter, depends on what kind of hibiscus you have. Some, like the Hardy Hibiscus, will die back to the ground in cold climates, but the roots will survive and sprout again next spring. Others, like Rose of Sharon, will keep their branches during the winter. Warmer climate varieties will need winter protection, such as mulching over the roots or wrapping.
Leaves look like they are being eaten.
Neem Oil is a good treatment for most infestations. Neem Oil is safe for people and pets!
Here is a few 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
Unlike in past, this year the plant has barely grown any new leaves at all - except tiny ones at the tips of the branches - despite regular watering and fertilizing with a balanced fertilizer. Cannot understand what exactly has gone wrong. Any tips or advice would be greatly appreciated.
If buds have not formed yet, you can prune the shrub.
It may be time for a good prune, which could result is loss of flowers for a season.
An overgrown Rose Of Sharon can be pruned in stages to reduce the shock, 1/3 of the shrub at a time is a good rule of thumb.
Do not over fertilize.
The articles below have care and pruning information.
https://www.gardeningknowhow.com/ornamental/shrubs/rose-of-sharon/pruning-rose-of-sharon.htm
https://www.gardeningknowhow.com/ornamental/shrubs/rose-of-sharon/rose-of-sharon-bush.htm
We have a hibiscus that has had all peach color flowers on it for 10-20 years. NO graphing!! Two weeks ago it got one brilliant red flower along with the peach on the same set of blossoms. Now it has another red one but not even from the same main branch as the first. Help me out,evolution? Will try sending a photo.
Yes, it is entirely possible!
This link will help you understand the causes.
http://www.hiddenvalleyhibiscus.com/misc/colors.htm
When I first brought it in for winter, it lost a lot of leaves. Then they grew back but now I have the middle stem that has its leaves starting to droop and I am not for sure what's wrong. Does it need fertilizer or what? I don't have it in sun but just light from kitchen where the sun shines in. Would be too cold for it?
Your Hibiscus likely needs a darker location and less watering during this winter dormancy period.
It is normal for the plant to lose leaves and some yellowing of leaves.
Do not fertilize the plant during the dormant period.
Here are some links with more information.
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/wintering-hibiscus-indoors-winter-care-for-hibiscus.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-fertilizing.htm
We live in Leesburg, Florida, about 40 miles north of Orlando. I have 2 hibiscus plants on the east side of my house; they get lots of sun. Problem is they're both losing all their leaves. I fertilize regularly with "hibiscus fertilizer" and water twice a week. They were planted 2 years ago and did well for the first 20 months.
A sudden loss of leaves usually indicates shock. The shock is caused by a sudden change in the plant's growing conditions. Overfertilizing, sudden changes in the air temperature, sudden changes in watering, and sudden changes in the amount of sun they get are often factors.