This is the prototype of my wheat farm. The one I made in my survival world is bigger. Much bigger.
Oy, John! Make sure each level is less than 7 blocks long or else the water won’t flow all the way.
The redstone will be on. When the power goes off the pistons will retract and let the water flow down and break the wheat.
These are regular pistons, FYI.
The stone slabs that you see in the middle prevent the water from flowing into the irrigation canal.
In the second picture I broke the slab just so you could see where the actual water for the crops goes.
On the final layer (the one before the collection canal) it needs to be 7 blocks long, no more no less.
Hope this helps!
Also, the texture pack that I used is Jolicraft, my favorite!