Hi Mckynzee, sorry for the delayed response. I was thinking of adding it to the left-most side of the moisture chart. It would also have unit gridlines that stretch across the chart. Gridlines would be able to be toggled on or off by the user. When off, you'd only get the left-most scale with tick marks for each unit of measurement. The tick marks for major units of measure would be longer horizontally than those depicting minor units.
If you'd like to take it one step further, you could show a graphic of grass or plant type for the zone on top above the center of the chart with a few roots depicting the watering depth. If in real time, you could add motion for wind speed effects (just to make it pretty). This would be more of a visualization tool for the technically challenged. This would also be able to be toggled on or off by the user.
Finally, for the Android and IOS apps we should be able to enlarge or shrink the size of the moisture chart by "pinching" the touch screen to show more or less detail. Currently, the moisture chart is programmed (or pinned) to one fixed size on the Android.