How do you grow a seedless orange tree?

It's a grafted tree. Tree cloning if you will. You can read all about it here:

https://homeguides.sfgate.com/plant-new-seedless-navel-trees-46498.html

https://en.m.wikipedia.org/wiki/Seedless_fruit

https://www.scientificamerican.com/article/how-do-seedless-fruits-ar/

Hi Tom, this is Peggy. From what I have read you need to "graft" a seedless fruit tree, since there are no seeds to plant. Here is an article about seedless plants. Good luck and Merry Christmas How Does Seedless Fruit Reproduce? - Chowhound

1. https://www.chowhound.com/food-news/54085/how-does-seedless-fruit-reproduce/
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Aug 20, 2007 - In a graft, the branch, vine, or bud is grown right into another plant's trunk or rootstalk. With the exception of seedless watermelons, which have ...

Hi there, Probably from a graft of some kind!

Most trees that produce any type of fruit are grafted. Pecan trees are grafted with the type of pecan that you want produced. Oranges, lemons, etc.....If you are knowledgeable about grafting it is something that you can do yourself.