I have noticed a white powdery substance around flowers in my hibiscus. Could you kindly suggest the remedy?
This is likely Powdery Mildew.
Here is a link with treatment information.
https://www.gardeningknowhow.com/plant-problems/disease/get-the-cure-for-powdery-mildew.htm
I have two hibicus trees that are sparse in their foliage, and I would like to know if pruning would help them bush up.
Yes, pruning will help the plant.
Here is a link to help you get started.
What bug riddles the hibiscus leaves with holes? The plant is in a sunny location and consistently watered. Is there any cure to rid the plant of whatever bug is destroying the leaves and decreasing bloom production?
This could be a few different insects or pests doing damage to the leaves.
Treat the plant with Neem Oil. Neem Oil is safe for people, pets and bees.
Here are some links for you.
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-sticky-leaves.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
Can a large patio Hibiscus be cut back in the winter for storing in the garage? In NW Tennessee we normally have lots of days below 32 degrees. I have a beautiful patio Hibiscus that is about 5 feet tall. If I transplant into a pot to save it, can I cut it back at the same time? I have covered it up during the last two nights of light frost. Thank you!
If you have below freezing temperature more than a couple of days, you will need to bring your tropical Hibiscus indoors.
Yes, you can prune back the plant by about 1/3 to help reduce the stress for the plant.
Here are some links for you.
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/tips-for-pruning-hibiscus-plants-when-to-prune-hibiscus.htm
I live in New Jersey. Have to leave my Hibiscus outside. How can I keep them alive through winter? Gets down to the teens in Jan. My Hibiscus are 4' braided trees in pots too large to move indoors. Can I keep them alive through the winter outdoors? Dec., Jan, and Feb could drop below freezing. What can I do?
You will want to move your Tropical Hibiscus indoors for the winter or risk losing them to the cold.
They will not survive temperatures below freezing.
Perhaps you could ask someone to help you move the large pots indoors.
Here is a link that will explain how to winter over your Hibiscus.
Do I cut back my Lord Baltimore in late fall and then store over winter?
Allow the plant to die all the way back, then cut the stems to about 3 inches from the ground. You can also wait and prune it back in the early spring.
It's best to mark the plant location and add some mulch to protect the plants roots.
It will regrow in the late spring and does need warm temperatures to break it's dormancy, colder climates it will take longer.
We are new to this home. The garden has two Hibiscus plants that are 9 feet tall. The bottom section (approx 12 stems each) appears to have been pruned at 2 feet. The remaining stems are at least double that number (24 to 30) and 7 feet tall have not been pruned at all. There are many stems going across the plants to the outside. They had only a few flowers this past spring and summer. However, they are now showing flowers at the ends of the stems. What and when should I do something?
I would wait until spring to prune and rejuvenate your plants.
Here is a link that will help you.
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/tips-for-pruning-hibiscus-plants-when-to-prune-hibiscus.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm