[Popman]

I remember a story that the Japanese (?) Breed a square watermelon to cut shipping costs and minimize damage...

[Pete from Shawnee Mission]

I think that they actually grow them in a form.

http://www.cnn.com/2001/WORLD/asiapcf/east/06/15/square.watermelon/index.html?_s=PM:asiapcf

(Snip)

“But clever Japanese farmers have solved this dilemma by forcing their watermelons to grow into a square shape. Farmers insert the melons into square, tempered glass cases while the fruit is still growing on the vine.

The square boxes are the exact dimensions of Japanese refrigerators, allowing full-grown watermelons to fit conveniently and precisely onto refrigerator shelves.”

[SgtHooper]

I think they simply raise them in square boxes. :-)