Hostas are "shade tolerant." Every plant needs light! Some hosta varieties do better in more sun or need sun to turn certain colors. A blue hostas' wax may melt in too much sun, making it green.  If a hosta is not growing or shrinking, it is likey from not enough light or tree roots!  Hostas grown in full sun will need more moisture. Their leaves may become smaller and more bleached. Their leaf size will be reduced even the following year if you moved them the previous year from full sun. They may multiply faster in full sun.