Q.Zebra grass
I have had a clump of zebra grass for years & it has not grown or hardly spread out !
I live in Ohio. It is on a sunny/part sunny area. What am I doing wrong??

Feed zebra grass lightly every spring, using a light application of a balanced, general-purpose garden fertilizer. A second application is necessary only if the zebra grass displays weak growth or if the foliage takes on a pale, yellowish color. Refer to the fertilizer container to determine specific rates of application.
Cut zebra grass down to within 5 inches before new growth emerges in spring. Removing old growth keeps the plant tidy and makes room for healthy new growth. Don't cut the plant down in autumn, because the foliage provides interest to the winter landscape.
https://www.gardeningknowhow.com/ornamental/foliage/maiden-grass/care-for-zebra-grass.htm