diff --git a/app/models/planting.rb b/app/models/planting.rb
index ab312f122..b28b11491 100644
--- a/app/models/planting.rb
+++ b/app/models/planting.rb
@@ -42,6 +42,6 @@ class Planting < ActiveRecord::Base
   end
 
   def planted_at_string=(str)
-    self.planted_at = Time.parse(str)
+    self.planted_at = str == '' ? nil : Time.parse(str)
   end
 end
diff --git a/spec/models/planting_spec.rb b/spec/models/planting_spec.rb
index 8dcffbdbd..00e4c7bb1 100644
--- a/spec/models/planting_spec.rb
+++ b/spec/models/planting_spec.rb
@@ -39,6 +39,11 @@ describe Planting do
     @planting.planted_at.should == Time.local(2013, 03, 01)
   end
 
+  it 'should accept blank dates' do
+    @planting.planted_at_string = ''
+    @planting.planted_at.should == nil
+  end
+
   it "should output dates in ISO format" do
     @planting.planted_at = Time.local(2013, 03, 01)
     @planting.planted_at_string.should == "2013-03-01"