Q.What Fertilizer Do I Use to Grow Larger Grapes
My grapes are 5 years old and they are very small. I want to know what do I need to grow them bigger?

Certified GKH Gardening Expert
I would have your soil tested first before adding anything to the soil to improve the quality of the fruit. A soil test will help you determine what is missing from the soil and what you may have too much off. This article on soil testing will help explain more and will also tell you where you can have your soil tested at inexpensively:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm