My hibiscus from last year won’t bloom
Green and leafy. No blooms.
YO, GREENVILLE PA -- that's where I'm from! Was just back home last September, beat it back to Florida before the winter started. (Whew!)
To answer your question, are you talking about a tropical hibiscus you have in a pot, or one of the hardy hibiscus that grow up north? Doesn't really matter..when plants have healthy leaves but no flowers, most of the time it's because there's too much nitrogen/not enough phosphorous, or too little sun. Fix the nutrient problem by adding some bonemeal to the soil, and adjust fertilizing in the future. For more light, move the plant, or (outdoors) trim something to let in more light.
Here are some tips on hibiscus growing: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm