How to Grow Mushrooms With Liquid Culture Made from Maple Tree Sap This YouTube video demonstrates how to create a liquid culture for growing mushrooms using sap from maple trees. You'll learn how maple trees have a sugar content of 1-2%, which is lower than the ideal 4% sugar content for mushroom mycelium. However, I show you how to make a low nutrient solution work for the liquid culture. The video takes you through the process of growing the liquid culture over three weeks, producing enough t