Firstly like the pear trees blue radishes don't turn back into planted ones after being harvested and have to be manually selected to harvested later.
Secondly banana trees and blue radishes have such a terribly slow maturation rate, I had a farm of each with about 40 trees (of each type) and it only just managed to spawn enough to keep 7 townies alive. Especially difficult as on jungle levels you can't make bread.

