Answer: Peaches are usually more temperamental than apple or plum so this is a little bit surprising. Your tree needs to flower before it can set fruit. If your tree is not flowering, that is one set of problems. If it is flowering but not setting fruit then there would be a different cause for that.
Generally speaking, they will do best in full sun all day. If they are in shade that would explain why they do not flower.
Winter damage can sometimes reduce fruiting by destroying flower buds during the winter. Cold hardiness is related to the specific variety you are growing as well as to the location where the trees are planted. In a very windy or exposed spot, and you are not seeing flowers, this might explain the problem.
You could also check the soil fertility by running some basic soil tests and see if anything is out of balance there that would cause them to fail to bloom or fail to develop fruit. Your local county extension can help you with the tests and interpreting the results.
Apple trees often need another apple variety nearby to serve as a pollen source. If your apple flowers but does not set fruit then that could explain it. You need to know what variety tree you have and then plant a suitable pollenizer.
Severe weather can cause fruiting to diminish -- drought is probably the most common cause, but a spring hail storm or late frost in spring while the trees are blooming can also cut the crop dramatically. Lack of bees to pollinate can also cause crop failure even though the trees bloom heavily.
I hope this gives you some ideas to trouble shoot. Your local county extension may also have some suggestions. Good luck with your trees!
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