Potatoes grow greenery on the top..............that supplies energy to the tuber and it grows into a potatoe...If you cut of those tops.................the potatoe will not grow................when the greenery dies off in the fall,,,,,,,,,,,,,,,get out the pitchfork and go under the tubers and carefully dig them up.............let them dry..........then brush off the dirt and store them in a cool dry place that between 34 & 40 degrees away from light.............a basement that does not freeze. I don't wash them until I am going to use them.