diff --git a/app/assets/javascripts/app/controllers/_ui_element/_application_selector.coffee b/app/assets/javascripts/app/controllers/_ui_element/_application_selector.coffee
index b6b2015ee..179362102 100644
--- a/app/assets/javascripts/app/controllers/_ui_element/_application_selector.coffee
+++ b/app/assets/javascripts/app/controllers/_ui_element/_application_selector.coffee
@@ -96,6 +96,8 @@ class App.UiElement.ApplicationSelector
           # ignore passwords and relations
           if row.type isnt 'password' && row.name.substr(row.name.length-4,4) isnt '_ids' && row.searchable isnt false
             config = _.clone(row)
+            if config.tag is 'textarea'
+              config.expanding = false
             if config.type is 'email' || config.type is 'tel'
               config.type = 'text'
             for operatorRegEx, operator of operators_type
diff --git a/app/assets/javascripts/app/controllers/_ui_element/core_workflow_condition.coffee b/app/assets/javascripts/app/controllers/_ui_element/core_workflow_condition.coffee
index 22d5e981a..da94185f7 100644
--- a/app/assets/javascripts/app/controllers/_ui_element/core_workflow_condition.coffee
+++ b/app/assets/javascripts/app/controllers/_ui_element/core_workflow_condition.coffee
@@ -153,6 +153,8 @@ class App.UiElement.core_workflow_condition extends App.UiElement.ApplicationSel
         # ignore passwords and relations
         if row.type isnt 'password' && row.name.substr(row.name.length-4,4) isnt '_ids' && row.searchable isnt false
           config = _.clone(row)
+          if config.tag is 'textarea'
+            config.expanding = false
           if config.tag is 'select'
             config.multiple = true
             config.default  = undefined
diff --git a/app/assets/javascripts/app/controllers/_ui_element/textarea.coffee b/app/assets/javascripts/app/controllers/_ui_element/textarea.coffee
index 3987bd43f..4ed6e555f 100644
--- a/app/assets/javascripts/app/controllers/_ui_element/textarea.coffee
+++ b/app/assets/javascripts/app/controllers/_ui_element/textarea.coffee
@@ -4,16 +4,17 @@ class App.UiElement.textarea
     fileUploaderId = 'file-uploader-' + new Date().getTime() + '-' + Math.floor( Math.random() * 99999 )
     item = $( App.view('generic/textarea')( attribute: attribute ) + '<div class="file-uploader ' + attribute.class + '" id="' + fileUploaderId + '"></div>' )
 
-    a = ->
-      visible = $( item[0] ).is(':visible')
-      if visible && !$( item[0] ).expanding('active')
-        $( item[0] ).expanding()
-      $( item[0] ).on('focus', ->
+    if attribute.expanding isnt false
+      a = ->
         visible = $( item[0] ).is(':visible')
         if visible && !$( item[0] ).expanding('active')
-          $( item[0] ).expanding().focus()
-      )
-    App.Delay.set(a, 80)
+          $( item[0] ).expanding()
+        $( item[0] ).on('focus', ->
+          visible = $( item[0] ).is(':visible')
+          if visible && !$( item[0] ).expanding('active')
+            $( item[0] ).expanding().focus()
+        )
+      App.Delay.set(a, 80)
 
     if attribute.upload
 
@@ -41,4 +42,4 @@ class App.UiElement.textarea
             debug: false
           )
       App.Delay.set(u, 100, undefined, 'form_upload')
-    item
\ No newline at end of file
+    item
diff --git a/public/assets/tests/qunit/form.js b/public/assets/tests/qunit/form.js
index 1562b53cf..e9edd224e 100644
--- a/public/assets/tests/qunit/form.js
+++ b/public/assets/tests/qunit/form.js
@@ -1607,3 +1607,27 @@ QUnit.test("form with external links", assert => {
   assert.equal('https://example.com/?q=133', el.find('input[name="a"]').parents('.controls').find('a[href]').attr('href'))
   assert.equal('https://example.com/?q=abc%20d', el.find('select[name="b"]').parents('.controls').find('a[href]').attr('href'))
 });
+
+QUnit.test("Fixes #3909 - Wrong size for textareas in triggers and core workflow.", assert => {
+  var done = assert.async(1)
+  $('#qunit').append('<hr><h1>Fixes #3909 - Wrong size for textareas in triggers and core workflow.</h1><form id="form21"></form>')
+  var el = $('#form21')
+  new App.ControllerForm({
+    el:        el,
+    model:     {
+      configure_attributes: [
+        { name: '3909_textarea_expanding', display: 'Textarea1', tag: 'textarea', rows: 6, limit: 100, null: true },
+        { name: '3909_textarea_no_expanding', display: 'Textarea2', tag: 'textarea', rows: 6, limit: 100, null: false, expanding: false },
+      ],
+    },
+    autofocus: true
+  });
+
+  new Promise( (resolve, reject) => {
+    App.Delay.set(resolve, 200);
+  }).then( function() {
+    assert.equal(el.find('textarea[name="3909_textarea_expanding"]').parent().hasClass('expanding-wrapper'), true, '3909_textarea_expanding has correct class')
+    assert.equal(el.find('textarea[name="3909_textarea_no_expanding"]').parent().hasClass('expanding-wrapper'), false, '3909_textarea_no_expanding has correct class')
+  })
+  .finally(done)
+});