Moisture content crossed threshold

The Moisture content crossed threshold trigger fires when a moisture reading crosses into a zone you define. A soil sensor dipping below a “water me” level, a sensor entering a healthy range after watering, or a reading escaping that range are all supported.

Use Moisture content crossed threshold to automate watering, alert you when a plant or material drifts out of its target range, or coordinate devices that respond to specific moisture levels.

Using this trigger from the user interface

If you prefer building automations visually, Home Assistant walks you through this trigger step by step. You pick what to watch, tweak a few options, and save. No YAML knowledge required.

To use Moisture content crossed threshold in an automation:

1. Go to Settings > Automations & scenes.
2. Open an existing automation, or select Create automation > Create new automation.
3. In the When section, select Add trigger.
4. Select what you want to monitor. Under By target (see Targets), pick the moisture sensor (for example, a soil moisture probe). You can also select an area, a device, or a label.
5. From the triggers shown for that target, select Moisture content crossed threshold.
6. Under Threshold type, configure the zone the reading must cross for the trigger to fire:
   • Select Above or Below and enter a value to fire when the reading crosses that level.
   • Select In range and enter a lower and upper bound to fire when the reading enters the range from outside.
   • Select Outside range and enter a lower and upper bound to fire when the reading leaves the range (crosses past either bound).
   • For each option, you can enter a fixed percentage (0–100%), pick a sensor entity, or a number helper entity as the threshold.
     • If you don’t have a number helper, you can create one by selecting Create a new number helper.
7. Under Trigger when (see Behavior), pick Each, First, or All to control how the trigger behaves when multiple entities are targeted.
8. Under For at least, set how long the reading must stay past the threshold before the trigger fires. Leave it at zero to fire immediately.
9. Select Save.

Options in the UI

Using this trigger in YAML

If you work directly in YAML, or you want to know exactly what Home Assistant does under the hood, this section has the technical reference. It lists the field names you use in YAML, their types, and which ones are required. For how an automation is built in YAML, refer to Automations in YAML.

In YAML, put the settings that are specific to this trigger under options. Keep target, if the trigger uses one, and general settings such as id, alias, enabled, and variables at the top level, next to trigger.

When this trigger starts an automation, it passes data about what happened to the automation. You can use this trigger data in the templates of your conditions and actions. To see which data is available, refer to Trigger data in templates.

In YAML, Moisture content crossed threshold is referred to as moisture.crossed_threshold. A basic example looks like this:

trigger: moisture.crossed_threshold
target:
  entity_id: sensor.tomato_soil_moisture
options:
  threshold:
    type: below
    value:
      number: 30

This fires when the tomato soil moisture sensor crosses below 30%.

To fire when the reading enters a healthy range:

trigger: moisture.crossed_threshold
target:
  entity_id:
    - sensor.tomato_soil_moisture
    - sensor.basil_soil_moisture
options:
  threshold:
    type: between
    value_min:
      number: 40
    value_max:
      number: 70
  behavior: each

To use a number helper as a dynamic threshold that you can adjust without editing the automation:

trigger: moisture.crossed_threshold
target:
  label_id: plant_sensors
options:
  threshold:
    type: below
    value:
      entity: input_number.plant_dry_threshold
  behavior: first

This fires when the first plant sensor with the plant_sensors label crosses below the threshold set in the number helper.

Options in YAML

Targets of the trigger

This trigger requires a target. The target is the object that Home Assistant will watch. You can select a single entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more], a device, an area, a floor, or a label as a target, and Home Assistant will watch every matching moisture sensor behind that target.

• Entity: one specific moisture sensor, such as sensor.plant_moisture.
• Device: every moisture sensor that belongs to a device.
• Area: every moisture sensor in a room or area.
• Floor: every moisture sensor on a floor.
• Label: every moisture sensor that shares a label.

You can also select different target types in one trigger. For example, you can add a specific entity and an area as targets in the same trigger to monitor both of them at once.

To learn which entities Home Assistant includes for a device, area, floor, or label, and how it handles several entities, refer to Automation targets.

Trigger variables

When the trigger reacts, the trigger variable identifies the entity that made it react. This is useful when a target contains multiple entities, such as a device, area, floor, or label.

The following trigger-specific variables are available:

• trigger.entity_id: Entity ID of the entity that made the trigger react.
• trigger.from_state: Previous state object of that entity.
• trigger.to_state: New state object of that entity.
• trigger.for: Timedelta object of how long the trigger criteria were met, if applicable.

For example, use {{ trigger.to_state.name }} in an action to include the name of the entity that made the trigger react in a notification.

The trigger variable describes the entity that made the trigger react. It doesn’t contain all the entities of the target.

Behavior with multiple targets

When you target more than one entity (or select an area, floor, or label that contains several), the Trigger when option controls how the trigger responds:

• Each (default): the trigger fires every time any one of the targeted entities transitions. For example, if you monitor three motion sensors in the living room and someone walks past sensor 1, the automation fires. When they walk past sensor 2 a moment later, it fires again. Every individual event counts.
• First: the trigger fires only on the first transition in the targeted group, then waits until none of the targeted entities is in that state anymore before it fires again. For example, if you monitor the same three motion sensors, the automation fires when the first one picks up movement (someone entered the room). The other two firing afterward are ignored, so you get one notification per “someone walked in” event instead of three.
• All: the trigger fires only after the last targeted entity in the group has fired, meaning all of them are now in the expected state. For example, if you monitor the lights in the living room, bedroom, and hallway, the automation fires only once all three have turned off. This is useful for scenarios like “start the robot vacuum only after every light on the floor is off,” so you know the room is truly empty.

Good to know

• This trigger works with sensors that have the moisture device class, such as soil moisture probes. For wet/dry leak sensors, use Moisture detected or Moisture cleared instead.
• If you use an entity as the threshold, it must use % as its unit. If it has a different unit, or no unit, the trigger doesn’t react.
• A crossing only fires once per direction. The reading must leave the zone and come back before it can fire again.
• To react on every change instead of only on crossings, use Moisture content changed.

Try it yourself

Ready to test this? Go to Settings > Automations & scenes, create a new automation, and add this trigger. Save the automation, and then make the trigger react. For example, change the state of the targeted entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more], turn on a light that the trigger monitors, or change its brightness. To check whether the automation ran, open its traces.

More examples

Real scenarios where this trigger fires in automations and scripts. Copy any example and adapt it to your setup. In the visual editor, select the UI options listed in the example when they are available, or paste the YAML code.

Automation: remind you to water a plant when soil moisture drops

When a plant’s soil moisture crosses below 30% and stays there for 30 minutes, send a reminder notification.

• Trigger: Moisture content crossed threshold
  • Target: Tomato soil moisture sensor
  • Threshold type: Below 30%
  • For at least: 00:30:00
• Action: Send a notification message
  • Target: My Device (notify.my_device)

alias: "Remind to water the tomatoes"
triggers:
  - trigger: moisture.crossed_threshold
    target:
      entity_id: sensor.tomato_soil_moisture
    options:
      threshold:
        type: below
        value:
          number: 30
      for: "00:30:00"
actions:
  - action: notify.send_message
    target:
      entity_id: notify.my_device
    data:
      message: "The tomatoes need watering."

Still stuck?

To find out why the trigger didn’t react, make the change that it should react to, and then open the traces of the automation. If the automation didn’t run, there’s usually no trace, but some triggers record a Did not trigger trace. For details, refer to Testing automations. For common problems and their solutions, refer to Troubleshooting automations.

If that doesn’t help, the Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with the trigger you’re using and what you expected to happen, or share on our subreddit /r/homeassistant.

Related triggers

Explore related triggers:

• Moisture content changed: Triggers when one or more moisture content values change.

• Moisture detected: Triggers when one or more moisture sensors start detecting moisture.

• Moisture cleared: Triggers when one or more moisture sensors stop detecting moisture.