Compatibility summary
You will need a travel adapter in Jersey; plug types used there differ from Germany.
Plug comparison
Germany plug types: C F
Jersey plug types: G
There is no common plug type between Germany (C F) and Jersey (G). You need a travel adapter.
Voltage comparison
Germany: 230V, 50Hz
Jersey: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.