With the GrowApp you can analyse the seasonal changes of the plants in your environment.  The educational research assignment on this page explains how you can do the analysis with students. In the assignment you follow the scientific research process.

1. Orientation

Answer the following questions for orientation. Use the answers to write your introduction. 

  1. Determine which of the six species that are part of the European GrowApp campaign are present in your  neighborhood (see picture below). 
  2. Which of these species or other species are you going to observe and why? Describe the environmental characteristics of the trees.
  3. Determine which phenophases are expected to happen during the time you have available for your observations (for example: leaf unfolding, flowering, fruit growth/ripening, leaf coloring, leaf fall).
  4. Provide some information on the phenophases you selected supported by images.
  5. With which other trees in which country/province are you going to compare the phenological development of your own tree(s).  Motivate your selection.

2. Research question

Identify research question(s) to be answered by your project.  Questions with yes or no answers are typically not good research questions; try to ask your research questions so that their answers help fill in gaps in the current understanding on your chosen topic.  Questions that begin with "How does…?" and "What is….?" are often better than "Is there…?"  Examples of research question that can be addressed with the GrowApp are:

  • What is the difference in phenological development between your tree and a tree of the same species from a different location in Europe? 
  • How is the timing of the phenological event that you study influenced by temperature?

3. Research plan


  • How often are you going to make photos with the GrowApp?
  • In what period are you going to make photos?
  • When during the day are you going to make photos?
  • From which exact location are you going to make photos? 
  • How are you going to compare the photos and animations that you obtain from the GrowApp?

4. Assemble data

Download the app on Currently, the GrowApp is only available for Android phones.

Make photos and animations with the GrowApp. Add a clear and short indication of the location from where you took the picture to the description field after you made the first photo at a new location. This will help other persons and yourself to find the location from where you took the first photo.

Also add an # with the English name of the species and an # with the name of the school. On the website you can filter all photos and animations with a certain #.

If you want to determine changes in greenness you need to download the individual photos that are part of the animation. You can do this by playing the animation on You can pauze the animation at each photo. With the right mouse button you can save the image to your computer.

Wheather data can be obtained from Enter the name of the location/municipality where your tree is standing in the search bar. By selecting ‘Month’ in the menu you can select the month for which you want to obtain both the observed and historic minimum and maximum temperature for each day. You should decide yourself for which days you need the weather information for your analysis.

5. Analyse your data

Try to answer your research questions. Depending on your research questions you have different options for your analysis:

5.1 Graph of phenological development

Compare the development of your tree(s) with the development of the other tree(s). Determine for each tree at what date you observe the phenophases of your interest.

Make a graph with on the horizontal axis the date and on the vertical axis the phenophases in chronological order (e.g. first leaves, 50% leaves unfolded, 100% leaves unfolded, first flower, full/100% flowering, etc.). You then can plot the development of the different trees with different colors. What do you see?

5.2 Graph of temperature dependence

Determine for each tree the date when your phenophase(s) occurred and calculate the average temperature in the preceding month(s). Preferably you select trees of the same species that are located far from each other. Make a graph with on the horizontal axis the average temperature of the selected months and on the vertical axis the date of the phenological event.

5.3 Determine the change in greenness over time

With the free software Analyzingdigitalimages (ADI) you can easily determine the greenness index of your whole photo or for specific parts of the photo. You can download the software from The Youtube film below explains in less than 3 minutes how you can calculate the greenness of the trees on your photos. 

You can plot the change in greenness over time by making a graph with on the horizontal axis the date and on the vertical axis the greenness index.