DIY GLOBE Plant Color Guide- a Fun Activity with Students

It’s that time of the year again! In the Northern Hemisphere, the chlorophyll in leaves are breaking down causing the green in leaves to disappear and allowing for orange and yellow colors to become visible. At GLOBE, we call this process Green-Down, and if you have not started collecting your Green-Down data yet, it's not too late*!

*If you are in the U.S., you can track the annual progressive changing of the leaves with this Fall Foliage Prediction Map from Smokey Mountains. (https://smokymountains.com/fall-foliage-map/)

The Green-Down protocol is a fairly simple one. The only “scientific instrument” you need to complete this protocol is a GLOBE Plant Color Guide. However, getting this item can present some of its own challenges. For one, it can be pricey. Because of the quality of the guide, it can can cost upwards of US$14.25 per chart (Forestry Suppliers). The second problem, is that it is not ubiquitous. A brief internet search only showed one vendor, Forestry Suppliers, and they unfortunately are currently out of stock at the moment.

So, I wanted to see if there was a way to make my own Plant Color Guide using common items. If I was successful, this seemed like a great classroom activity to do with students.

My first attempt was to see if there were common products with the specific color quality required. Fortunately, there is a wealth of information about the color values of common art supplies listed by their hexidecimal color code. Unfortunately, the GLOBE Color chart uses Munsell color codes.

The next step was to convert Munsell colors to hexidecimal (or hex) colors, which turns out to be less straightforward than converting Fahrenheit to Celsius. When I tried using several different conversion websites, I got different color codes each time. Which means, there is not an exact conversion when it comes to colors. Of the sites that I tried, my favorite was encycolorpedia.com because it could give a fairly accurate color conversion and it had a wealth of other color-related information including commercial paints that have the exact or similar color.

I then created a spreadsheet with the converted hex codes that I got from a couple of different sites and was delighted to discover that the text and background colors in your favorite document creating platform (such as Microsoft Excel) are all hexidecimal. Which meant, I could change the cells of my spreadsheet to the colors in my Plant Color Guide chart by inserting the hex code. When I printed my “Excel Chart” out and compared the colors to my GLOBE Plant Color Guide, some of the colors were perfect matches and some were not. Was this a problem of my conversions or a printer problem? I was not sure, and since printers and inks can vary so much across the world, asking people to print their own color charts could not be the solution to the problem.

I then turned to one of the most common art supplies around, the crayon. GIO conveniently had a box of 48 Crayola and 24 RoseArt crayons hiding in the depths of storage. I compared the GLOBE Plant Color Guide to crayon scribbles and found a few matches. Then I tried some color combos and found a few more matches.

I did not find enough matches from my crayon collection to complete the set (I ended up with 17 out of the 24 color matches). However, I felt pretty confident that if I kept going and tried more crayons (hello Crayola 64 pack!) or different mediums (markers, acrylic paints, paint chips, makeup palettes?) I could create a near perfect replica of the color chart just using products I could readily and cheaply find. What’s more, it was a fun project. I liked combining science and art and it was something that would easily translate to a project for STEAM (science, technology, engineering, art, mathematics) teachers to do with a wide age-range of students.

Before I send teachers off with the project of creating their own Color Charts, there a few things to keep in mind.

1. Unlike my unreliable printed version of the color chart, the actual GLOBE Plant Color Guide product has the exact colors you need to determine the colors of the leaves, shrubs, and grasses you are measuring. When creating your own chart, you want the colors to be exact (or as close to exact as possible) matches to the colors on the charts. Therefor, it is advisable to have at least one copy of the actual GLOBE Color Chart on hand to compare your homemade charts to. That way you can make sure your color chart replicates are still accurate and you are still collecting accurate data.

2. The values you enter into the GLOBE Database still need to reflect the Munsell colors from the GLOBE Color Plant Guide. Make sure you properly label your color chart replicates with the corresponding Munsell values. GLOBE will only accept 5G 8/4 and not Crayola Sea Green, for example.