diff --git a/src/main/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModel.java b/src/main/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModel.java
index 25f96d14edb3c56713ba3df8868137c3da9a68a7..91da5f9bca6768e8d0a2d08d4bd2c8b94f4e68e2 100755
--- a/src/main/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModel.java
+++ b/src/main/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModel.java
@@ -73,6 +73,7 @@ public class RoughageNutritionModel implements Model {
     
     private Date firstHarvest;
     private Date secondHarvest;
+    private Date firstPossibleGrowthStartDate;
     private Integer soilType;
     private Integer cloverShare;
     private List<OptimizationObservation> optimizationObservations;
@@ -90,6 +91,7 @@ public class RoughageNutritionModel implements Model {
                 Q0D, 
                 firstHarvest, 
                 secondHarvest, 
+                firstPossibleGrowthStartDate,
                 soilType, 
                 cloverShare, 
                 optimizationObservations, 
@@ -246,7 +248,7 @@ public class RoughageNutritionModel implements Model {
             List<WeatherObservation> globalStraaling, Q0
             Date foersteslaatt, 
             Date andreslaatt, 
-            Date tidligsteVekststart,
+            Date tidligsteVekststart, // Default: 1. mars
             int jordtype, 
             int kloeverandel, 
             List<OptimizationObservation> observasjoner
@@ -289,6 +291,20 @@ public class RoughageNutritionModel implements Model {
         {
             this.secondHarvest = mapper.convertValue(config.getConfigParameter("secondHarvest"), Date.class);
         }
+          
+        if(config.getConfigParameter("firstPossibleGrowthStartDate") != null)
+        {
+            this.firstPossibleGrowthStartDate = mapper.convertValue(config.getConfigParameter("firstPossibleGrowthStartDate"), Date.class);
+        }
+        else
+        {
+            Calendar cal = Calendar.getInstance();
+            cal.setTime(firstHarvest);
+            cal.set(Calendar.MONTH, Calendar.MARCH);
+            cal.set(Calendar.DATE, 1);
+            this.firstPossibleGrowthStartDate = cal.getTime();
+        }
+        
         if(config.getConfigParameter("soilType") != null)
         {
             this.soilType = mapper.convertValue(config.getConfigParameter("soilType"), Integer.class);
@@ -309,6 +325,8 @@ public class RoughageNutritionModel implements Model {
         
         
         
+        
+        
         List<WeatherObservation> observations = mapper.convertValue(config.getConfigParameter("observations"), new TypeReference<List<WeatherObservation>>(){});
         
         for(WeatherObservation o:observations)
diff --git a/src/main/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModelImpl.java b/src/main/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModelImpl.java
index 31fea1e9c8e23169908306dd0d9b058b3c0ef3eb..c2730bcf3be34e983396daed7412f86fb0fe4190 100755
--- a/src/main/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModelImpl.java
+++ b/src/main/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModelImpl.java
@@ -33,6 +33,7 @@ import java.util.TimeZone;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import java.util.stream.Collectors;
 import no.nibio.vips.entity.WeatherObservation;
 import no.nibio.vips.model.ModelExcecutionException;
 
@@ -43,12 +44,15 @@ import org.apache.commons.math.optimization.CostException;
 import org.apache.commons.math.optimization.CostFunction;
 import org.apache.commons.math.optimization.NelderMead;
 import org.apache.commons.math.optimization.PointCostPair;
+import org.slf4j.LoggerFactory;
 
 /**
  * @copyright 2018 <a href="http://www.nibio.no/">NIBIO</a>
  * @author Tor-Einar Skog <tor-einar.skog@nibio.no>
  */
 public class RoughageNutritionModelImpl implements CostFunction {
+    
+    private static final org.slf4j.Logger LOGGER = LoggerFactory.getLogger(RoughageNutritionModelImpl.class);
 
     // Globale variable som må nullstilles for hver beregning av modellen
     private List<WeatherObservation> nedboerVerdier;
@@ -67,6 +71,7 @@ public class RoughageNutritionModelImpl implements CostFunction {
 
     private Date datoFoersteSlaatt;
     private Date datoAndreSlaatt;
+    private Date foersteMuligeVekststartdato;
 
     private Integer jordtype;
     private Integer kloeverandel;
@@ -135,6 +140,7 @@ public class RoughageNutritionModelImpl implements CostFunction {
             List<WeatherObservation> dailyGlobalRadiation,
             Date firstHarvest,
             Date secondHarvest,
+            Date firstPossibleGrowthStartDate,
             int soilType,
             int cloverShare,
             List<OptimizationObservation> optimizationObservations,
@@ -150,6 +156,7 @@ public class RoughageNutritionModelImpl implements CostFunction {
         this.datoAndreSlaatt = secondHarvest;
         this.jordtype = soilType;
         this.kloeverandel = cloverShare;
+        this.foersteMuligeVekststartdato = firstPossibleGrowthStartDate;
         this.calculatedDateOfGrowthStart = null;
         this.timeZone = timeZone;
 
@@ -456,6 +463,8 @@ public class RoughageNutritionModelImpl implements CostFunction {
         Integer dagNummer = 1;
         for (Iterator<WeatherObservation> tempI = this.luftTemperaturVerdier.iterator(); tempI.hasNext();) {
             temperatur = tempI.next();
+            
+            
 
             // Beregner TS1
             double TS1;
@@ -1221,17 +1230,30 @@ public class RoughageNutritionModelImpl implements CostFunction {
 
     /**
      *
-     * @return @throws com.ac.march.ModelExcecutionException
+     * @return 
+     * @throws no.nibio.vips.model.ModelExcecutionException 
      */
     protected Date getVekstStart() throws ModelExcecutionException {
         if (this.calculatedDateOfGrowthStart == null) {
-            this.calculatedDateOfGrowthStart = this.getVekstStart(this.luftTemperaturVerdier, this.jordTemperaturVerdier);
+            // Filtrer bort datoer før første mulige vekststartdato
+            if(this.foersteMuligeVekststartdato != null)
+            {
+                List<WeatherObservation> TMFiltrert = this.luftTemperaturVerdier.stream()
+                        .filter(wo->wo.getTimeMeasured().compareTo(this.foersteMuligeVekststartdato) >=0 )
+                        .collect(Collectors.toList());
+                List<WeatherObservation> TJMFiltrert = this.jordTemperaturVerdier.stream()
+                        .filter(wo->wo.getTimeMeasured().compareTo(this.foersteMuligeVekststartdato) >=0 )
+                        .collect(Collectors.toList());
+                this.calculatedDateOfGrowthStart = this.getVekstStart(TMFiltrert, TJMFiltrert);
+                LOGGER.debug("calculatedDateOfGrowthStart=" + this.calculatedDateOfGrowthStart);
+            }
+            
         }
         return this.calculatedDateOfGrowthStart;
     }
 
     /**
-     * Beregner datoen hvor vekststart antas å inntreffe. Vekststart antas å
+     * Beregner datoen hvor vekststart antas å inntreffe.Vekststart antas å
      * inntreffe etter tre påfølgende femdøgnsmiddel av temperatur > 5 grader
      * Celcius. Dvs. datoen blir den tredje av disse påfølgende femdøgnsmiddel.
      * Endring 2013-10-06: Hvis vi har jordtemperatur tilgjengelig, så må det
@@ -1242,6 +1264,7 @@ public class RoughageNutritionModelImpl implements CostFunction {
      * @param jordTemperatur
      * @return Dato for vekststart, eller null hvis ikke betingelsene for
      * vekstart er oppfylt i de gitte klimadata
+     * @throws no.nibio.vips.model.ModelExcecutionException
      */
     protected Date getVekstStart(Collection dognMiddelLuftTemperatur, Collection jordTemperatur) throws ModelExcecutionException {
         double lufttempTerskel = 5.0;
diff --git a/src/test/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModelTest.java b/src/test/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModelTest.java
index efc61196f058d65e47f147286845058d69e7068d..94073fd0ef76cf528b7c9170601484ca875833c6 100755
--- a/src/test/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModelTest.java
+++ b/src/test/java/no/bioforsk/vips/model/roughagenutritionmodel/RoughageNutritionModelTest.java
@@ -49,7 +49,7 @@ import static org.junit.Assert.*;
 
 /**
  *
- * @author treinar
+ * @author Tor-Einar Skog <tor-einar.skog@nibio.no>
  */
 public class RoughageNutritionModelTest {
     
@@ -86,6 +86,9 @@ public class RoughageNutritionModelTest {
             cal.set(Calendar.MILLISECOND,0);
             config.setConfigParameter("timeZone","Europe/Oslo");
             config.setConfigParameter("firstHarvest", cal.getTime());
+            cal.set(Calendar.MONTH, Calendar.APRIL);
+            cal.set(Calendar.DATE, 15);
+            config.setConfigParameter("firstPossibleGrowthStartDate", cal.getTime());
             config.setConfigParameter("soilType", RoughageNutritionModel.JORDTYPE_SAND);
             config.setConfigParameter("cloverShare", RoughageNutritionModel.ENGSAMMENSETNING_KLOEVERANDEL_LITEN);
             String[] optimizationInfoLines = {"2016-06-02,2,3,,,,"};