diff --git a/homeassistant/components/plant/__init__.py b/homeassistant/components/plant/__init__.py
index c4abc916c3f..0b2ffe6d8cb 100644
--- a/homeassistant/components/plant/__init__.py
+++ b/homeassistant/components/plant/__init__.py
@@ -363,7 +363,7 @@ class DailyHistory:
     def add_measurement(self, value, timestamp=None):
         """Add a new measurement for a certain day."""
         day = (timestamp or datetime.now()).date()
-        if value is None:
+        if not isinstance(value, (int, float)):
             return
         if self._days is None:
             self._days = deque()
@@ -388,4 +388,6 @@ class DailyHistory:
             oldest = self._days.popleft()
             del self._max_dict[oldest]
         self._days.append(day)
+        if not isinstance(value, (int, float)):
+            return
         self._max_dict[day] = value