Please be advised, we do not recommend using a non-standard cable other than supplied 3M cable with the IntelliLink kit. However, if you really need to use extended USB cable, you may buy following USB 2.0 extenders (or any other as you deem suitable) at your own discretion.
This kind of set-up is not supported by the Autogrow but we do endeavour to help our growers.
Technical reason why longer USB cable is not supported: Autogrow controllers are optimised for low power consumption hence a longer USB cable may not be able to carry a signal for longer distance and results intermittent connection issue. If the connection is lost, it will appears as "Disconnected" in your online IntelliGrow account but it will still function as programmed.