This Fall, 2025, in Northern Ohio it seemed like Fall Color came and went without much fanfare. Colors were muted and the leaves seemed to fall off the trees quickly. In past years, fall colors have been brilliant. So, what happened this year? Why the change?

As the sun sets on fall color (Image), there was and still is fall color this year. But you need to look closely (Image).

Some vines that are still in fall color including Virginia creeper, Parthenocissus quinquefolia and Poison Ivy Toxicodendron pubescens.

Some shrubs and small trees showing color are Virginia sweetspire, Itea virginica and Japanese maple, Acer palmatum.

Also, Sourwood, Oxydendrum arboreum, is beautiful, as well as Perrotia, Parrotia persica.

Red maples, Acer rubrum and Sugar maples, Acer saccharum are just ready to drop their leaves but the oak leaves are hanging on the trees.

Scarlet Oak, Quercus coccinea

White Oak, Quercus alba

Swamp white oak, Quercus bicolor

Chinkapin oak, Quercus muehlenbergii, Red oak, Quercus rubra and Pin oak, Quercus palustris

With the cold temperature, high winds, and heavy rain and snow in the forecast, the leaves and colors may end up on the ground and in piles for raking (Image).

First, we need to start with some basics. What is fall color? What are the pigments in the leaves? Why do some trees turn consistently yellow? Why are some oranges? Why are some red? Why are some browns? Why does it happen? Why can it vary year by year?

That is a lot of questions. Hopefully, our explanations will provide insight.

Pigments found in deciduous tree leaves include chlorophylls, carotenoids, (xanthophyll, beta-carotene), anthocyanins, and tannins to name the most common.

Most leaves are green due to the high concentration of chlorophyll which is the pigment essential for photosynthesis, the process by which plants convert sunlight into sugar. During spring the leaves start out a light green as the concentration of chlorophyll begins to increase. This light green color turns to a darker green as spring progresses to summer. Through the growing season, trees are producing and storing sugars as well as putting on growth. Throughout the summer the chlorophyll is replenished so that it can function as the light receiving molecule. Carotenoids and other pigments are present in the leaves but are masked by the high concentration of chlorophyll. As summer transitions into autumn, the regeneration of chlorophyll slows and eventually stops.

The class of pigments called carotenoids include yellow and orange pigments (think of a carrot) and they serve to protect the photosynthetic components from damage. Xanthophyll, a subclass of carotenoids, is responsible for the yellow fall colors we see as in birch, elm and Japanese Katsura tree, Cercidiphyllum japonicum. (Image, Image)

Xanthophylls were first described in fall leaves in 1837. Beta-carotene reflects yellow and red light making the leaves of sugar maples and yellow buckeyes, Aesculus flava, appear orange.

Another class of pigments are the anthocyanins that can be vivid red, purple, magenta, and in some flowers true blues. Anthocyanins are affected by the pH of the sap giving a range of colors. Anthocyanins are not typically present in high concentrations in most leaves during the summer with the exception being plants like the purple leaf forms of plants like Cercis canadensis 'Forest Pansy' Forest pansy redbud, or Fagus sylvatica 'Purpurea', purple leaf European beech. The production of anthocyanins can be triggered by many things including cold. Bright sunny days and cold night temperatures in fall can lead to increased concentrations of anthocyanins as the chlorophyll is being degraded.These are the pigments that make the vivid red of red maple Acer rubrum and the deep red or burgundy that are present in many of the oaks including Scarlet oak, Quercus coccinea and White oak, Quercus alba.

Tannins are large complex polyphenolic compounds. During the growing season tannins serve as defense compounds to protect the leaves against fungal and bacterial infections and to deter feeding by insects and other animals. In autumn, they work to protect the leaves from UV light. Because of their size and complexity, tannins degrade more slowly and are the last pigments present. They are mainly brown and are found in high concentrations in many oak leaves (Image).

So, what is the trigger to begin fall color? The end of summer! Specifically, shorter daylengths trigger changes in the leaf chemistry that begin long before we see any change in color. The longer nights signal the process to breakdown of the chlorophyll and the recycling of nutrients out of the leaves. As the chlorophyll is degraded, the presence of the carotenoids is revealed. Cooler night temperatures also play a role. Although this is not required to trigger fall color, a frost can accelerate the color change and the intensify the various pigments in a tighter window of time putting on a great show of fall color (Image, Image).

A good fall color show is connected to healthy growing trees and sufficient moisture in the soil.

What happened to fall color this year? Northern Ohio experienced a moderate to severe drought, for much of the summer and fall. Trees were stressed and this directly affects the fall color display. As a survival response to drought conditions, leaves abscised quickly and dropped off the trees to minimize water loss. Because of this drought response, the gradual recycling of the chlorophyll and nutrients was limited and the typical change revealing the masked colors were muted or almost nonexistent.

Most of what we are experiencing now are the anthocyanins and tannins on oaks that are displaying dark burgundy and brown colors (Image).

But looking closely, there is still fall color out there if you look:

Black gum, Nyssa sylvatica - Zelkova, Zelkova serrata - Yellow buckeye, Aesculus flava - Ginkgo, Ginkgo biloba - Sassafras, Sassafras albidum

Sweetgum, Liquidambar styraciflua - Oakleaf hydrangea, Hydrangea quercifolia - Flowering dogwood, Cornus florida - Hackberry, Celtis occidentalis

Red maple, Acer rubrum - Eastern redbud, Cercis canadensis - Bald cypress, Taxodium distichum - Red twig Dogwood, Cornus sericea and Shagbark hickory, Carya ovata

So, what about next year? The short answer is, “It’s up to Mother Nature.’

A normal growing season including sufficient and timely moisture, normal temperature ranges of maximum and minimum temperatures through the growing seasons, and a minimum of extreme weather including wind and rain, fall color would tend to be fairly normal which can be anything than average, but spectacular (Image)!

Winter is coming!

Read more about pigments: https://www.purdue.edu/uns/html4ever/1995/9509.JOLY.html

Another article that highlighted fall color was written by Erik Draper: https://bygl.osu.edu/index.php/node/1885

Ron Wilson

In The Garden With Ron Wilson