Most nursery, hardware and big box stores sell a device for this. It is made of wire, round and has a grid of squares across the round part. It has 3 wire legs. When the plants are still short/small, put the device over the plant. The wire legs stick deeply into the ground. As the plant grows, the stems come up through the wire squares. You pull the legs out of the ground just a little bit and let the plant grow taller. This happens again and again until you have only enough wire legs in the ground to support the plant. These are great for perennial hibiscus. Sort of like a wire 'frog' for a vase.

My suggestion for your towering hibiscus is to insert three
bamboo poles, in a half circle, 5 or 6 bamboo poles if the plant is very wide. As you form the half circle, make sure the bamboo poles are deep in the ground to support the plant weight. Apply twist tie garden wire to the bamboo poles at three tier cascading levels.Then,apply cotton laundry line rope onto the twist tie. Use extra long lengths of twist garden tie to secure the cotton rope into one length-piece.Gradually, tighten the rope level, allowing the hibiscus plant to drape over the cotton rope. Whenever I support a plant, I gradually raise or tighten the support patten over a week in order to visualize and modify the support pattern. Always, communicate the assigned endeavor to the plant.

regards,
guara

p.s. I have yellow and white hibiscus plants. Pureed green
peppers mixed with pureed green hibiscus leaves is a natural dye for cotton rope. Be creative when supporting your plants.I hope this helps.

Thank you both for your suggestions. I will try your method or methods in the spring.