Leaf wetness chart card

Who it’s for

Agronomists, precision farmers, and vineyard managers ask “how has leaf wetness changed over the selected period, and is the canopy drying out or staying wet?” They want the current index, a trend line, and a period-over-period delta in one card to time spray decisions accurately.

What it does

A sensor averaging 72% this week versus 30% last week shows an orange value — Wet — with a +140% delta and a +42% absolute change, plus a chart of readings over the period.

• Large current leaf wetness value color-coded across four bands from Dry to Saturated
• Delta percentage and absolute delta comparing the current period to the previous one
• Time-series chart of wetness readings averaged per interval
• Shows one sensor’s data; it does not compare multiple canopy zones

How to set up

Data keys

Key	Role	Type	Description
leaf	Chart series	Timeseries	Leaf wetness index in %; drives the chart and all derived overlays
Latest	Latest value	Timeseries	The headline figure above the chart. Its own color ranges are where the band colors are edited
Delta percent	Percentage change	Timeseries	Change against the previous period, as a percentage
Delta absolute	Absolute change	Timeseries	Change against the previous period, in the key’s own unit

The widget ships with a simulated function datasource key labeled Leaf wetness, so it draws random values until you point the datasource at a device and rename the key.

To point it at your own device: open the dashboard in edit mode, open the widget’s Datasources, pick the entity or entity alias, and replace the function key with the key your device reports.

If the key has never reported for the selected time window, the chart is empty and all overlays show no data.

Value ranges

Range (%)	Level	Color
0–10	Dry	Blue
10–50	Moderate	Orange
50–90	Wet	Orange
90+	Saturated	Red

How to customize

• To use your own wetness thresholds — edit the color ranges on the Latest data key; adjust the four default bands to match your crop’s spray thresholds.
• To change the comparison period — adjust the Time window on the dashboard; the delta automatically compares to the equivalent preceding period.
• To hide or show the chart — toggle Show chart in the widget settings.
• To change the chart line color — set Chart color.
• To show min, max, or total in the legend instead of avg — edit the Legend settings.
• To hide the entity name subtitle or the timestamp — turn off Show subtitle or Show date.

Tips

• A sharply rising delta after overnight rain signals the canopy moved from Dry to Wet — the critical window for preventive fungicide application is the first 12–24 hours of sustained wetness.
• Use this card when the period-over-period change matters. If you only need the trend shape without a delta, use the simple leaf wetness chart card instead.