There are three things to be concerned about when it comes to spraying blueberry plants. Fertilizing, fungicide, and insecticide. When spraying your blueberry plants you simply cover the leaves with the spray. When spraying your blueberry plants you do not have to cover it thick. As long as all the blueberry leaves get sprayed that is what you are going for. Anytime you are using a spray it is important to read the directions first. If you are using a granular for fertilizing simply follow the instructions on the package. For a list of when to spray and what sprays to use for a home gardener see our spray guide for home gardeners page.