[DuncanWaring]

How far apart should fruit trees (apple/pear/peach) trees be planted?

I’ve heard anywhere from 10’ to 20’.

[greeneyes]

It kinda depends on the fruit tree, and the type. There’s the standard size, the dwarf size, and something in between for lots of fruit trees.

Then there’s the “columnar” trees. So you would have to know the anticipated height and diameter of the mature tree to be able to answer the question.

Usually, the catalog or instructions that come with the tree contains that info.

[Sarajevo]

Check the tree information. I've planted mine on 20ft centers. Plant them approx. 1.5x of the adult tree crown diameter apart. Take yearly trimming into consideration also.
You want easy access for picking fruit and no overlap of the branches of neighboring trees.

[Texas Fossil]

I planted mine with 18’ seperation and offset every other row 9’ to minimize the root overlap. Am happy with that scheme. It does make it necessary for me to plow diagonal across the rows and straight down the rows with the run.

If you have rabbits, I suggest welded wire cages to prevent them from eating the bark away on the trees. The damaged some of mine before I caught that. If you let them the little vermin will absolutely kill fruit trees. They “like” the way they taste.