Ground temperature chart card

Who it’s for

Farmers and agronomists monitoring field conditions ask “is the soil warming up or cooling down, and how fast compared to last week?” A single snapshot does not say whether the ground is heading into a frost or into planting range; the trend does.

What it does

A sensor averaging 12°C this week, up from 6°C last week, shows a +100% delta in red — the soil is warming fast. The chart below confirms the upward trend over the selected period.

• Large current ground temperature in the center, color-coded across seven bands from Very Cold to Very Hot
• Percentage change vs. the previous period, with a colored arrow — red when temperature is rising, blue when falling
• Absolute temperature change in °C shown below the delta percentage
• Time-series chart of ground temperature readings over the selected time window, averaged per interval
• Shows one sensor’s data; it does not compare multiple field zones

How to set up

Data keys

Key	Role	Type	Description
temperature	Chart series	Timeseries	Ground temperature in °C; drives the chart. The Latest, Delta percent, and Delta absolute overlays are automatically derived from this same key
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 Ground temperature, 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 (°C)	Level	Color
< −20	Very Cold	Deep Blue
−20–0	Cold	Blue
0–10	Cool	Light Blue
10–20	Moderate	Orange
20–30	Warm	Orange
30–40	Hot	Red-Orange
40+	Very Hot	Red

How to customize

• To use your own temperature thresholds — edit the color ranges on the Latest data key; adjust the seven default bands to match your crops’ requirements.
• To switch to Fahrenheit — set Units to °F and update the color range boundaries to match.
• 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.
• To match your dashboard’s fonts — set the font options under each data key’s appearance settings.

Tips

• A rising delta in spring means planting conditions are improving. A falling delta in autumn warns of approaching frost.
• Pair this card with a frost alert rule to get notified when a falling trend pushes the ground below 0°C.