diff --git a/app/models/planting.rb b/app/models/planting.rb
index 2e9e22149..b9566c62b 100644
--- a/app/models/planting.rb
+++ b/app/models/planting.rb
@@ -109,17 +109,17 @@ class Planting < ActiveRecord::Base
     end
   end
 
-  def planted?(current_date = DateTime.now)
+  def planted?(current_date = Date.today)
     planted_at.present? && current_date.to_date >= planted_at
   end
 
-  def percentage_grown(current_date = DateTime.now)
+  def percentage_grown(current_date = Date.today)
     return nil unless days_before_maturity && planted?(current_date)
 
+    days = (current_date.to_date - planted_at.to_date).to_i
+
     return 0 if current_date < planted_at
     return 100 if days > days_before_maturity
-
-    days = current_date - planted_at
     percent = (days/days_before_maturity*100).to_i
 
     if percent >= 100
diff --git a/spec/models/planting_spec.rb b/spec/models/planting_spec.rb
index 1575c9320..90b4da713 100644
--- a/spec/models/planting_spec.rb
+++ b/spec/models/planting_spec.rb
@@ -57,13 +57,13 @@ describe Planting do
 
       now_earlier_than_planting = 2.days.ago
 
-      @planting.percentage_grown(now_earlier_than_planting).should be 0
+      @planting.percentage_grown(now_earlier_than_planting).should be nil
     end
 
     it 'should reflect the current growth' do
       @planting = FactoryGirl.build(:planting, days_before_maturity: 10, planted_at: 4.days.ago)
 
-      @planting.percentage_grown.should be 40
+      @planting.percentage_grown(Date.today).should be 40
     end
 
     it 'should not be calculated for unplanted plantings' do