Answer: There isn't anything that you can add to the soil, or the growing conditions that will influence the peach flavor. Some varieties don't have as good a flavor as others. This is a common complaint about dwarf peach trees. They were bred for tree size, and not peach flavor. When the peaches are allowed to ripen naturally, they produce their own sugars in the process. If you don't give the peach the right conditions and time to produce these sugars, they will indeed, be bitter. Before harvesting, check to see if they are soft, and have a peach aroma. Use the flat of the palm, and not the fingers to check softness. This will prevent finger bruises.
Some ways to judge when the peach is ripe is to check the following:
Yellow under color; Peachy aroma; Tender flesh; Heavy for size; Well defined crease.
Hope this information is helpful!
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