diff --git a/content/en/docs/concepts/storage/persistent-volumes.md b/content/en/docs/concepts/storage/persistent-volumes.md
index 28fc8b4f1a1ef..c9d583ce32de0 100644
--- a/content/en/docs/concepts/storage/persistent-volumes.md
+++ b/content/en/docs/concepts/storage/persistent-volumes.md
@@ -227,8 +227,17 @@ kubectl describe pvc <pvc_name>
 
 If the `PersistentVolumeClaim` has the status `FileSystemResizePending`, it is safe to recreate the pod using the PersistentVolumeClaim.
 
+FlexVolumes allow resize if the driver is set with the `RequiresFSResize` capability to true. 
+The FlexVolume can be resized on pod restart as 'ExpandPersistentVolume' feature gate is enabled by default. 
+
 #### Resizing an in-use PersistentVolumeClaim
 
+Expanding in-use PVCs for FlexVolumes is added in release 1.13. To enable this feature use  `ExpandInUsePersistentVolumes` and `ExpandPersistentVolumes` feature gates. The `ExpandPersistentVolumes` feature gate is already enabled by default. If the `ExpandInUsePersistentVolumes` is set, FlexVolume can be resized online without pod restart. 
+ 
+The FlexVolume plugin uses RequiresFSResize to identify and resize the Persistent Volume. The underlying driver must support resize, if not an error will be returned and Persistent Volume object will not change and the expand request will fail. FlexVolume driver must implement the method `ExpandFS` defined in the interface `FSResizableVolumePlugin` along with `ExpandableVolumePlugin` interface and its method `ExpandVolumeDevice`.
+The Flex driver should implement ExpandableVolumePlugin interface only if it is to be installed on the controller/master.
+The Flex driver should implement any volume expansion methods along with FS resize in ExpandFS method if the Flex driver is installed on the worker nodes but not on the controller or master node.
+
 {{< feature-state for_k8s_version="v1.11" state="alpha" >}}
 
 Expanding in-use PVCs is an alpha feature. To use it, enable the `ExpandInUsePersistentVolumes` feature gate.