Apple Chilling Info: How Many Chill Hours Do Apples Need

By Amy Grant If you grow apple trees, then you are no doubt familiar with the chill hours for apple trees. For those of us who are new to cultivating apples, what exactly are apple chill hours? How many chill hours do apples need? Why do apple trees need chilling? It all seems a bit confusing, but the following article contains all the apple chilling info you are likely to need. Apple Chilling Info So you’re immersed in choosing bare root apple trees from a catalogue for your particular USDA zone and notice that not only is the hardiness zone listed but another number as well. In the case of apples, these are the number of apple chill hours needed for the tree. Okay, but what the heck are chill hours for apple trees? Chill hours or chill units (CU) are the number of hours when temperatures stay at 32-45