Question
I have a patio peach tree that I bought about 3 years ago at Lowes and planted in the ground, the tree looks healthy & leaves are green but the fruit does not get big or ripe and usually just rots and falls off

Answer
Hi Donna, you didn't mention where you live, but there are Peach trees that are of the "southern" variety that have peaches that only get to be about the size of a common egg; the reason yours are not developing is probably because you need to cull off a large number of them when they first appear, this gives the tree the energy to put into developing the rest into egg size fruit. The ones that are  rotting and falling off may be because of the Caribbean Fruit Fly larvae, the adult lays an egg in the fruit when it is just beginning the ripening process, and the larvae feeds inside causing the subsequent "rotting" of the fruit. Nick