There are two ways the device counts Intensity Minutes (IM).
The default way is using your average Resting HR (RHR) - when your HR during the day reaches certain level above the RHR (in my case around 150%), the IMs start to increment. The earlier condition of the necessity of minimally 10 consecutive minutes in the IM zone was lately abandoned, but some older devices, or devices with older firmware may still require it.
The other way (optional, on some devices) is using HR Zones. In that case your HR must be in the configured zone for the IM or for the vigorous IM.
If you post a screenshot of your HR during the gardening, the value of your RHR for given day, and the screenshot of your IM settings, then we can tell you whether you deserved to get some IMs for it, or not.
