The Root Cellar is about feeding yourself. It's popular because it has the best quality of produce consistently all year round. And the shopping environment is pleasant. They also try to source as much locally as they possibly can. Lately their butcher shop -in store has also gotten quite good (but it's a bit pricy relative to standard markets.
You will need to drive or cycle there. Consider combining an outing there with a visit to Mount Doug Park.
Mon-Su: 08:00-20:00