You have good instincts as both your hardy hibiscus and hydrangea should be allowed to go dormant this winter. Once the leaves fall, turn off the grow lights and allow the plants only the sunlight from the garage window. No plant food and very little water should be offered. You want the young plants to sleep. In spring when you see daffodils in bloom turn on the grow lights again for about 8 hours a day and fertilize once you see new leaves. Then when foliage appears set grow lights for 16 hours and try to move plants outdoors on mild days so they get used to wind. Around May the weather should be settled enough for the potted plants to go into the ground and you can congratulate yourself on starting new shrubs. Keep growing, Marianne Binetti