Do mushrooms need light to grow?

Yes. Even though mushrooms don’t require light for photosynthesis (like plants) they still require light to form fruiting bodies. When growing indoors, indirect sunlight from a window should suffice. However, if you decide to grow in a dark or windowless area (like a garage, basement, or closet) you will need to supplement light with a compact fluorescent lightbulb or LED strip in the blue spectrum (above 5000K).