Growing Hibiscus?

It looks like these are well established hibiscus plants so they must have been in the ground for several years. Your zone must be in the high numbers or these plants would not have survived the winter months.

Hibiscus generally need to be pruned every year and really should not have other plants/weeds growing in their "space". For a beginning, take a good look at your plants and try to determine what is really wrong - you can read about the problems with growing hibiscus and see if your plants match any of the conditions noted. This is the only way to help your plants. It really looks like your plants need a good pruning for a start and maybe try to clear some of the area around their root system.
Here is an excellent site that has listed most of the problems - with solutions - that may help save your plants. Read everything and just keep hitting "next" at the bottom of the page as there are several pages of information.

www.gardeningknowhow.com/.../tips-for-pruning-hibiscus-plants...