Yes, you can assign a single sensor to multiple zones.

In the Spruce App

To use one sensor for multiple zones, they must be grouped into a “Zone Group”. All zones in the group need to have the same zone settings in order for the “Create Zone Group” option to appear. This restriction is in place  because in order to control and scale watering appropriately and consistently, Spruce needs the zones that are sharing a single sensor, to be similar.

Create a Zone Group

1. Go to “Device Settings”
2. Go to each zone that you would like to group together and ensure the zone settings are identical to the other zones for the group
3. Go to “Create Zone Group”
4. Zones that are identical will be available for selection
5. Select the zones to group, give the group a name and save
6. These zones will now be grouped together and can share a sensor

In the Scheduler SmartApp

The same sensor can be assigned to multiple sensors. It makes the most sense to do this when the soil type, landscape type, and wind and sun exposure are similar between zones.

Spruce will calculate watering times based on the moisture data from its assigned sensor before watering begins on any of the zones, so there is no need to worry about zones skipping watering due to multiple zones being assigned to the same sensor.