Go to the map in the bottom right hand corner and go to the Retail Office. It will automatically pop up a screen and you can choose to upgrade your farm.
Yes you need ifile with a jailbroken iphone Go to: Ifile then,mobile,applications,go to home and settings and change it to view names,then click on farm town,and then documents,continue to click on...
to do this click where you want to make a plowed field and keep clicking as fast as you can and you should make another one over it keep doing till sattisfied then for plants keep clicking like...