Fall color show still on hold

The Register-Mail explores why fall colors aren’t at their finest yet. Miava Reem, Knox greenhouse supervisor, and Stuart Allison, Knox associate professor of biology, comment on how leaves change color.

Excerpt:

While vendors and gawkers prepare for traditional fall events like the Knox County Scenic Drive, unseasonably warm temperatures could translate into a delay before October offers its full palette of fall colors.

“I know there isn’t a lot of change going on right now,” Miava Reem said. “I would be surprised to see a lot leaves change color until you start to see cooler temperatures – at least some cool temperatures at night.”

Reem serves as academic support staff for Knox College’s biology department and has overseen the college’s greenhouse for 14 years.

Galesburg’s average temperature this September is 69.2 degrees – above the normal average of 64.7 degrees. Those higher temperatures is one of the factors that retards many leaves’ change from green to yellow, orange and red.

But temperature isn’t the only factor that determines when leaves change color.

“The thing is, you just never know,” Reem said. “The two main factors that determine when leaves change are the length of the day and temperature.

“In general – first and foremost – the changing color is based on the length of the day. When it starts to get dark earlier, photosynthesis stops.”