We recommend using a Female-to-Female Stemma Connector and plugging it in between the PyPortal and the STEMMA Soil Sensor. No soldering is involved - just connect the cable between the Stemma Soil Sensor and the PyPortal's I2C port.
The cable makes the following connections between the PyPortal's I2C port and the STEMMA Soil Sensor:
That's it - your PyPortal is wired up!
When you're ready, just stick the STEMMA Soil sensor into your plant's soil. Be sure to leave the white portion of the sensor not covered by soil. You may also want to position the sensor at the edge of your plant's pot.