According to Fitbit, gardening is cycling
One of FitBit's more useful features is its ability to automatically detect exercise. I think it uses a combination of your heart rate and how the device is moving.
The pattern of motion and heart rates must be categorised by FitBit so the app can tell the difference between "swimming" and "running", etc.
It's not a precise system though.
This is my private server for all things related to my website and YouTube channel.
So I always recommend people to buy a hoe instead of some shape-up gadget,
and become a volunteer gardener (for me)!