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Junior Fall Garden Detectives

By Mary Gadek, Master Gardener

The blustery days of fall yield a kaleidoscope of leaves across our Minnesota yards and parks. Have your children ever wondered why these leaves transform to new colors in the fall? Help your child become a Junior Fall Garden Detective by gathering clues, using some scientific observations and then searching outside to solve this mystery of why leaves change colors in the fall.

Junior Fall Garden Detectives

Calling all Junior Fall Garden Detectives! Let’s find out what the clues are for why leaves convert from the summer color of green to red, orange, yellow, or brown shades as they fall to the ground. Once the clues are known, pull on your coziest sweatshirt and head outside to observe the evidence of fall leaves’ transformation, revealed in trees and creatures in our yards and parks. By using your observation skills, you can solve the mystery of why leaves are now changed to a new hue.




Have you ever noticed how the leaves on the trees and bushes seem to suddenly turn from green to deep reds, yellows and oranges seemingly out of nowhere this time of year? Most of the year, the special chemical inside of leaves, called chlorophyll, gives leaves their green tint. The chlorophyll helps leaves absorb energy from sunlight during a process called photosynthesis, which converts the energy into sugar to feed the trees or plants.


As the seasons change from summer to fall, the air temperatures drop and the days get shorter. Look for these clues for when leaves will begin to change color:


  1. Air temperatures. The Minnesota average temperatures on September 1 are 77 degrees daytime, 59 degrees nighttime. By November 1, the temperatures have decreased to an average of 50 degrees daytime, 35 degrees nighttime.

  2. Daylight. From the start of school in early September until now in October, you probably have noticed less daylight each day as you hop on your school bus in the morning until you are playing at the park at the end of the day. Daylight on average decreases by one hour and 15 minutes from August 1 through October 15.


As the trees and plants get less sunlight, the chlorophyll in the leaves breaks down. With less chlorophyll, yellow and orange color pigments replace the green color of summer. Sometimes darker red leaves appear as the sugar produced in the leaves stays in the leaves (instead of feeding the tree), because the tree has stopped its growth for the year.



Venture outside to your yard or local park to find the clues of fall to predict when the leaves will be changing colors: the cooler air at your soccer game requiring a need for your favorite sweater and the sun setting earlier over the horizon of the local lake.


What evidence do you observe that the clues have encouraged the leaves to start transforming?


  1. Trees. Trees and bushes are dropping an array of leaves with bright reds, yellows, oranges and browns. Burning bush (or Euonymus alatus), along with oaks and maple trees create intense red leaves. River birch and yellow poplar trees have showy yellow displays in the fall. 

  1. Creatures. The arrival of fall invites the creatures in your yard, or local park, to either migrate to the warmer south, or prepare to hunker down for the Minnesota winters by making nests or dens.  Birds, like Canadian geese, wood ducks and the loon, form flocks and fly south. Look up to the autumn sky as the migrating birds fly in triangular formation to head to warmer locations.  Butterflies, like the monarch, partake in a long journey to winter in warm Mexico. You may notice that the butterflies are no longer to be found in the garden. Other animals, insects and birds remain in Minnesota during the winter by hibernating, or sleeping, in covered areas or under the brush of the colorful fallen leaves and nearby evergreens. Look closely, squirrels are collecting seeds and acorns to save up for their winter meals.



Want to prove that the fall leaves have been changed due to the cooler air and shorter days? Bundle in a warm jacket and take a hike around your yard and neighborhood with your family or friends. Make sure to get outside during daylight as the sun sets earlier so you can accumulate the evidence of the leaves changing colors. Collect as many leaves as possible or help rake your yard. Notice all the beautiful colors!


Have a contest: 1. Who gathered the most leaves? 2. Who picked up the most red/yellow/orange/brown leaves? Celebrate the results by making a leaf pile and jumping in it together! 


Activity: Find your favorite leaf from your collection. With the help of an adult, cut two equally measured squares of wax paper (about 1” larger than your chosen leaf). Insert the leaf between the two wax papers. With an iron on the lowest setting and a cloth over and underneath the wax papers, briefly hold the iron on the top cloth until the wax papers melt together. What a brilliant fall keepsake you have created!


To reinforce the information from this article and to learn more about the concepts, here are some additional resources to explore:


  1. Follow the monarch migration:

  2. Read: Goodbye Summer, Hello Autumn by Kenard Pak ISBN: 9781627794152 (Dakota County Library) or buy at Amazon:  A children’s book describing the clues and evidence discussed above for fall leaves.



Photo credits: Mary Gadek (1,2,3), Book Jacket (4)

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