My hibiscus plants are 3 yrs. old. The blooms are only opening up partially. What am I doing wrong?
My Hibiscus Blooms Are Only Opening Up Partially
Hard to say without knowing what kind of hibiscus you have. Flower-of-an-hour don't open on cloudy days, for instance. https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/flower-of-an-hour-info.htm
Hardy hibiscus are reliable to zone 4, and flowering might be held back by too much shade or fertilizer imbalance - too much nitrogen, for instance. Here's an interesting article on them: http://web.extension.illinois.edu/dmp/palette/090712.html
Then you might have tropical hibiscus in a pot, which is another situation entirely. Here's some info on those: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm