Quantity   Component name
1 × Arduino Nano V3 I used a compatible board.
1 × "Chirp" capacitive soil moisture sensor
1 × DHT22
1 × CWX-15Q CR-02 Valve
1 × 2-channel relay board, 5V I personally used a 4-channel module to have room for further expansion.These relay baords are typically marked "Arduino"-compatible and very cheap.
1 × LM2596 regulator board Basically, any circuit that will give you 5V from your battery.
1 × 12V Battery I used a 7.2Ah maintenance-free lead battery. Use whatever is convenient.
1 × Fuse + Fuse holder