diff --git a/homeassistant/components/letpot/number.py b/homeassistant/components/letpot/number.py
index a5b9c3df68c1..2061b419ddb5 100644
--- a/homeassistant/components/letpot/number.py
+++ b/homeassistant/components/letpot/number.py
@@ -12,7 +12,7 @@ from homeassistant.components.number import (
     NumberEntityDescription,
     NumberMode,
 )
-from homeassistant.const import PRECISION_WHOLE, EntityCategory
+from homeassistant.const import PRECISION_WHOLE, EntityCategory, UnitOfTime
 from homeassistant.core import HomeAssistant
 from homeassistant.helpers.entity_platform import AddConfigEntryEntitiesCallback
 
@@ -72,6 +72,7 @@ NUMBERS: tuple[LetPotNumberEntityDescription, ...] = (
     LetPotNumberEntityDescription(
         key="plant_days",
         translation_key="plant_days",
+        native_unit_of_measurement=UnitOfTime.DAYS,
         value_fn=lambda coordinator: coordinator.data.plant_days,
         set_value_fn=(
             lambda device_client, serial, value: device_client.set_plant_days(
diff --git a/homeassistant/components/letpot/strings.json b/homeassistant/components/letpot/strings.json
index 4c46e1ddbb16..3af8c7e3db67 100644
--- a/homeassistant/components/letpot/strings.json
+++ b/homeassistant/components/letpot/strings.json
@@ -54,8 +54,7 @@
         "name": "Light brightness"
       },
       "plant_days": {
-        "name": "Plants age",
-        "unit_of_measurement": "days"
+        "name": "Plants age"
       }
     },
     "select": {
diff --git a/tests/components/letpot/snapshots/test_number.ambr b/tests/components/letpot/snapshots/test_number.ambr
index 50f6cf64312e..4784cfa695a4 100644
--- a/tests/components/letpot/snapshots/test_number.ambr
+++ b/tests/components/letpot/snapshots/test_number.ambr
@@ -93,7 +93,7 @@
     'supported_features': 0,
     'translation_key': 'plant_days',
     'unique_id': 'a1b2c3d4e5f6a1b2c3d4e5f6_LPH63ABCD_plant_days',
-    'unit_of_measurement': 'days',
+    'unit_of_measurement': <UnitOfTime.DAYS: 'd'>,
   })
 # ---
 # name: test_all_entities[number.garden_plants_age-state]
@@ -104,7 +104,7 @@
       'min': 0.0,
       'mode': <NumberMode.BOX: 'box'>,
       'step': 1,
-      'unit_of_measurement': 'days',
+      'unit_of_measurement': <UnitOfTime.DAYS: 'd'>,
     }),
     'context': <ANY>,
     'entity_id': 'number.garden_plants_age',