Savannah, GA (WSAV) – With it finally starting to feel like fall outside, it’s time for it look like it as well. No, I don’t mean the festive Halloween and fall decorations you have outside your home. I’m talking about leaves naturally changing to beautiful orange and red colors.
While some leaves have begun to change color here and there, peak foliage doesn’t truly begin for us until the end of October through the beginning of November. Unfortunately, the peak doesn’t last too long and leaves begin to turn brown within a week or two.
You can pull the hidden colors from leaves in a full experiment at the bottom! It’s super fun, easy, and kid-friendly!
Hidden Colors in Leaves
During the spring and summer, we get a lot of sunlight. Plants need that extra sunlight to make chlorophyll. Chlorophyll is the green color found in plants and algae. Chlorophyll helps plants make energy from the sun’s light in a process called photosynthesis.
Once we enter fall, the days get shorter and we see less and less sunlight. This means plants aren’t able to make enough chlorophyll to keep that vibrant green color and the color begins to fade. Yellow, orange, and red colors start to show on leaves.
Leaves actually already have these colors in them because of their different chemicals called pigments. Green has the color Chlorophyll in it, yellow has Xanthophylls, orange has Carotenoids, and red has Anthocyanins. Chlorophyll is much more dominant than the other chemicals that it covers up the rest until it begins to break down.
How Weather Changes Leaf Colors
Just like how weather impacts our own every day lives, weather can affect when the foliage peaks and how vibrant the leaf colors will be.
BRIGHTNESS: For the brightest and most vibrant peak colors, we need to have seasonally warm afternoons and cool nights leading up to leaves beginning to change. During the day, sunshine helps leaves produce an abundance of sugars and energy. As temperatures cool overnight, the sugar energy remains trapped in the leaf as the leaf’s veins shrink. This is sort of like when in the cold, your fingers shrink as your blood vessels constrict to keep you warm.
Trapping the extra energy leads to the production of bright anthocyanin chemicals, bringing out the red colors.
In a warmer setting in which we have hotter afternoons and warm to mild nights, the leaf soaks up an abundance of sugar. Instead of trapping it in overnight, the warm air allows for the leaf’s veins to remain open and the energy is released. This leads to a lower amount and production of anthocyanin chemicals, allowing for more muted colors.
A warm stretch during the fall can also cause leaves to fall off the trees early before the leaf colors have truly changed.
MOISTURE: The vibrancy and timing of when the leaves change are also impacted by how much rain we see and how wet the soil remains through much of the year. For the best viewing, we need to have a moist soil throughout the year combined with warm days and cool nights to keep the colors glowing.
If we have a dry to drought conditions through late summer, this could delay the leaves changing color. Drought conditions create sealing barriers between the leaf and the tree, cutting off the moisture supply. This also could lead to leaves falling earlier than color changes and peak foliage.
With more rain fall, leaves have enough moisture to live with more time to hit peak colors before falling. Leaves under these conditions don’t create barriers between them and the moisture supply. This gives leaves the optimal time to change color.
We’ve had a combo of moist soil and warm days and nights. This is leading to leaves dropping faster than peak fall coloration and causing colors not to be as vibrant. I’ve seen this already on a few trees near my home. Leaves with more green hues than yellow or red hues have already dropped to the ground, leaving trees almost bare.
Separating green and yellow pigments found in different leaves.
SCIENCE BEHIND CHROMATOGRAPHY: the separation of a mixture (chlorophyll from the leaves in the alcohol) by passing it as a vapor (rubbing alcohol evaporates up the filter) through a medium (coffee filter) in which the components move at different rates (green and yellow colors show up at different parts of the filter).
1. Cut leaves up into small pieces and put them into the cups or jars.
2. Pour rubbing alcohol into cups; just enough to cover leaves.
3. Use end of a spoon to gently chop and grind the leaves into the alcohol. This will help the chlorophyll start to break down.
4. Cover the cups or jars loosely with a lid, plastic wrap, or aluminum foil.
5. Set cups in a bowl and add hot water to the bowl.
– Be sure to fill bowl with enough water to reach the alcohol level outside the cup.
6. Leaf (ha! get it…leave) the cups to sit for about 1 hour. Swirl glasses every 10 minutes to help mix the leaves and the alcohol together.
– You may need to replace the hot water before the hour is up because the water will cool.
7. Check to see if the alcohol has a green or yellow tint from the leaves. The color should be bright.
– You may need to leave cups in hot water a little bit longer if alcohol isn’t showing color.
8. Cut coffee filters into long strips and cut one connected end.
9. Take cups out of water and put coffee filter strips into mixture. Leave alone for 30-90 minutes.
10. The tinted alcohol will slowly travel up the paper. As the alcohol evaporates, you will notice the colors traveling at different distances up the filter.
11. Remove filter and place on plate. Allow filter to dry. Colors will show up as it dries.