We have had them 3 years; have had a very hot dry summer in Arizona.
These are very heavy feeders. If they do not get fed a few times per year, then they are just lacking in nutrients. These articles will help: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/answers-to-what-causes-hibiscus-leaves-turning-yellow.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-fertilizing.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm
I live in Hawaii. The hibiscus plants are in large pots. There are no pests evident on the buds or leaves but a lot of buds turn yellow and fall off before opening.
This can have a few causes.
The most common is lack of nutrients, or the wrong kind of nutrients. Too much nitrogen, or not enough phosphorus and potassium will cause bloom drop. You can offset by adding nutrients high in phosphorus and potassium, and continue with a high nitrogen feed during growing season when it is not blooming.
Another cause is not enough sun. They will grow very bushy in partial shade, but will not flower as well. They prefer full sun for proper bloom-set.
These articles will help: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-fertilizing.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/outdoor-hibiscus-care.htm
THE LANDSCAPER AT SEABREEZE CONDO TOLD ME HE CANNOT USE FERTILIZER CONTAINING NITROGEN FROM JUNE TO NOV. ONLY A FEW BLOOMS ON MANY PLANTS. BEFORE PRUNING IN LATE MAY, THERE WERE SO MANY BEAUTIFUL BLOOMS. THEY ARE JUST FULL MOF GREEN LEAVES. WHAT FERTILIZER SAFE FOR SOUTHEAST COAST OF FL?
Hibiscus should be fertilzied with a balanced fertilizer regularly but lightly to avoid overfertilization, which will result in less blooms. Here is the schedule and type of fertilizer
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-fertilizing.htm
My hibiscus has red spider. We have tons of spruce trees outside! HELP! Lana
It is very important to take all necessary precautions to ensure that systemics are used correctly. This article will help you with systemic use: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/systemic-pesticide-in-gardens.htm
Alternatively, you can use an organic systemic such as neem oil. This article will help: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
Acids in Rosemary oil have shown promise as a systemic as well, and is used by several companies for organic systemic pesticides.
I have many seeds from a Texas Red Star hibiscus and want to grow the plants from those. What is the proper way to do that.
These articles should help:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-propagation.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/growing-texas-star-hibiscus.htm
I have a Hibiscus Sabdariffa that I planted beside my house for a nice "bush" plant. Now I live in Southwestern Pennsylvania and our winters can get pretty cold. Will my hibiscus plant survive over winter, also how big will it get. I thought only the size of a bush, but someone told me it will get big like a tree. Help!
It is tropical and won't survive a Pennsylvania winter. You can grow it in a pot during the summer and overwinter inside. You can trim it to a manageable size.
https://www.gardeningknowhow.com/ornamental/flowers/roselle/growing-roselle-plants.htm
Do I have to continue watering the hibiscus plants and when can they be pruned?
Plants should be well hydrated going into dormancy to ensure their survival. If soil drys out completely, roots will dry out and die. Common hibiscus is pruned in early spring. It blooms on wood that is formed in late spring and early summer.
A link to more information follows: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/tips-for-pruning-hibiscus-plants-when-to-prune-hibiscus.htm