diff --git a/src/main/java/no/nibio/vips/logic/modules/roughage/RoughageService.java b/src/main/java/no/nibio/vips/logic/modules/roughage/RoughageService.java
index bc4d9511ac2f49cfc1cb3d86939fe78d6747709a..d0af049bd7be820e6a86ffdc3532d01ba9b9a264 100755
--- a/src/main/java/no/nibio/vips/logic/modules/roughage/RoughageService.java
+++ b/src/main/java/no/nibio/vips/logic/modules/roughage/RoughageService.java
@@ -104,6 +104,7 @@ public class RoughageService {
             @QueryParam("wateringAffectsNormalData") String wateringAffectsNormalData,
             @QueryParam("firstHarvest") String firstHarvestStr,
             @QueryParam("secondHarvest") String secondHarvestStr,
+            @QueryParam("firstPossibleGrowthStartDate") String firstPossibleGrowthStartDateStr,
             @QueryParam("soilType") Integer soilType,
             @QueryParam("cloverShare") Integer cloverShare,
             @QueryParam("userWeatherScenarios") String useWeatherScenarios,
@@ -119,21 +120,23 @@ public class RoughageService {
         TimeZone timeZone = TimeZone.getTimeZone(timeZoneStr);
         Date firstHarvest = parseUtil.parseISODate(firstHarvestStr, timeZone);
         Date secondHarvest = secondHarvestStr != null ? parseUtil.parseISODate(secondHarvestStr, timeZone) : null;
-        // Calculating start and end date of weather data retrieval
-        // Start is April 1st
-        Calendar cal = Calendar.getInstance(timeZone);
-        cal.setTime(firstHarvest);
-        cal.set(Calendar.MONTH, Calendar.MARCH);
-        cal.set(Calendar.DATE, 1);
 
+        // Calculating start and end date of weather data retrieval
+        // Start is March 1st unless specified otherwise
+        Date firstPossibleGrowthStartDate = firstPossibleGrowthStartDateStr != null ? parseUtil.parseISODate(firstPossibleGrowthStartDateStr, timeZone) : null;
         WeatherUtil wUtil = new WeatherUtil();
-        Date marchFirst = wUtil.normalizeToExactDate(cal.getTime(), timeZone);
-
+        Calendar cal = Calendar.getInstance(timeZone);
+        if(firstPossibleGrowthStartDate == null) {
+            cal.setTime(firstHarvest);
+            cal.set(Calendar.MONTH, Calendar.MARCH);
+            cal.set(Calendar.DATE, 1);
+            firstPossibleGrowthStartDate = wUtil.normalizeToExactDate(cal.getTime(), timeZone);
+        }
         // End date for weather data depends on season
         // We try September 30th. If that's in the future,
         // We add 10 days to today
         Date dateOfLastWeatherData;
-        cal.setTime(marchFirst);
+        cal.setTime(firstPossibleGrowthStartDate);
         cal.set(Calendar.MONTH, Calendar.SEPTEMBER);
         cal.set(Calendar.DATE, 30);
         Date endOfSeptember = cal.getTime();
@@ -164,7 +167,7 @@ public class RoughageService {
                         WeatherElements.SOIL_TEMPERATURE_10CM_MEAN,
                         WeatherElements.POTENTIAL_EVAPORATION
                     },
-                    marchFirst, 
+                    firstPossibleGrowthStartDate,
                     dateOfLastWeatherData
             );
         } catch (WeatherDataSourceException ex) {
@@ -367,9 +370,10 @@ public class RoughageService {
         config.setConfigParameter("observations", observations);
         config.setConfigParameter("timeZone", timeZone.getID());
         config.setConfigParameter("firstHarvest", firstHarvest);
+        config.setConfigParameter("firstPossibleGrowthStartDate", firstPossibleGrowthStartDate);
         config.setConfigParameter("soilType", soilType);
         config.setConfigParameter("cloverShare", cloverShare);
-        
+
         // Optional parameters
         if(secondHarvest != null)
         {
@@ -426,7 +430,7 @@ public class RoughageService {
                         WeatherElements.SOIL_TEMPERATURE_10CM_MEAN,
                         WeatherElements.POTENTIAL_EVAPORATION
                     },
-                    marchFirst, 
+                    firstPossibleGrowthStartDate,
                     //dateOfLastWeatherData
                     latestObsDate
                 );