diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java
index c4f556db2..46fd64b6a 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java
@@ -99,8 +99,6 @@ public class GanttDiagramGraph<V, D extends IDependency<V>> implements
 
         void setEndDateFor(V task, GanttDate newEnd);
 
-        GanttDate getSmallestBeginDateFromChildrenFor(V container);
-
         public List<Constraint<GanttDate>> getConstraints(
                 ConstraintCalculator<V> calculator, Set<D> withDependencies,
                 Point point);
@@ -213,12 +211,6 @@ public class GanttDiagramGraph<V, D extends IDependency<V>> implements
             return task.getEndConstraints();
         }
 
-        @Override
-        public GanttDate getSmallestBeginDateFromChildrenFor(Task container) {
-            return ((TaskContainer) container)
-                    .getSmallestBeginDateFromChildren();
-        }
-
         @Override
         public boolean isFixed(Task task) {
             return task.isFixed();
@@ -844,8 +836,7 @@ public class GanttDiagramGraph<V, D extends IDependency<V>> implements
 
         boolean enforceParentShrinkage(V container) {
             GanttDate oldBeginDate = adapter.getStartDate(container);
-            GanttDate firstStart = adapter
-                    .getSmallestBeginDateFromChildrenFor(container);
+            GanttDate firstStart = getSmallestBeginDateFromChildrenFor(container);
             GanttDate previousEnd = adapter.getEndDateFor(container);
             if (firstStart.after(oldBeginDate)) {
                 adapter.setStartDateFor(container, firstStart);
@@ -856,6 +847,18 @@ public class GanttDiagramGraph<V, D extends IDependency<V>> implements
         }
     }
 
+    private GanttDate getSmallestBeginDateFromChildrenFor(V container) {
+        List<V> children = adapter.getChildren(container);
+        if (children.isEmpty()) {
+            return adapter.getStartDate(container);
+        }
+        List<GanttDate> dates = new ArrayList<GanttDate>();
+        for (V each : children) {
+            dates.add(adapter.getStartDate(each));
+        }
+        return Collections.min(dates);
+    }
+
     List<Recalculation> getRecalculationsNeededFrom(V task) {
         List<Recalculation> result = new LinkedList<Recalculation>();
         Set<Recalculation> parentRecalculationsAlreadyDone = new HashSet<Recalculation>();
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/TaskContainer.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/TaskContainer.java
index bcbf6faf7..7035c9582 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/TaskContainer.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/TaskContainer.java
@@ -87,21 +87,6 @@ public class TaskContainer extends Task {
         return tasks;
     }
 
-    public GanttDate getSmallestBeginDateFromChildren() {
-        if (tasks.isEmpty()) {
-            return getBeginDate();
-        }
-        return getSmallest(getStartDates());
-    }
-
-    private List<GanttDate> getStartDates() {
-        ArrayList<GanttDate> result = new ArrayList<GanttDate>();
-        for (Task task : tasks) {
-            result.add(task.getBeginDate());
-        }
-        return result;
-    }
-
     private List<GanttDate> getEndDates() {
         ArrayList<GanttDate> result = new ArrayList<GanttDate>();
         for (Task task : tasks) {
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/common/TemplateModelAdapter.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/common/TemplateModelAdapter.java
index e895ed896..d87e9408c 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/common/TemplateModelAdapter.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/common/TemplateModelAdapter.java
@@ -11,7 +11,6 @@ import org.apache.commons.lang.Validate;
 import org.joda.time.LocalDate;
 import org.navalplanner.business.planner.entities.TaskElement;
 import org.navalplanner.business.planner.entities.TaskElement.IDatesInterceptor;
-import org.navalplanner.business.planner.entities.TaskGroup;
 import org.navalplanner.business.scenarios.entities.Scenario;
 import org.navalplanner.business.workingday.IntraDayDate;
 import org.navalplanner.web.common.TemplateModel.DependencyWithVisibility;
@@ -78,12 +77,6 @@ public class TemplateModelAdapter implements
         return toGantt(task.getIntraDayEndDate());
     }
 
-    @Override
-    public GanttDate getSmallestBeginDateFromChildrenFor(TaskElement container) {
-        TaskGroup taskGroup = (TaskGroup) container;
-        return toGantt(taskGroup.getSmallestStartDateFromChildren());
-    }
-
     @Override
     public TaskElement getSource(DependencyWithVisibility dependency) {
         return dependency.getSource();