The recent spell of warm and dry weather this fall has created conflicting cues for trees regarding the timing of leaf color change, according to a local expert.
“What typically signals a tree that it’s time to change color is days are getting shorter, nights are getting colder. Days are getting shorter. That happens every year. But this year, we’re seeing that the warm weather typically tends to prolong fall color and delay it. However, dry weather can accelerate fall color and make it happen early,” said Dr. Christine Rollinson, a senior scientist in forest ecology at The Morton Arboretum.
“So this year, honestly, week to week, it’s kind of like, ‘Wait, are we early? Are we late?” Rollinson added.
When do fall colors peak?
Rollinson said the average time of year when fall colors peak varies depending on location. Across the Chicago region, widespread fall colors tend to appear around mid-October, which could still be the case this year, depending on the upcoming weather.
“As October keeps rolling along, the conditions day to day can have a really big impact on the exact timing. So if we do get cold next week, that’s going to start speeding things along. If we get rain, that might delay some things. So constantly be looking out your own window to see what’s going on,” said Rollinson.
The Morton Arboretum offers a fall color report, providing weekly updates on the hues its tree species are displaying.
Not all tree species change the same color or at the same rate. Maple trees tend to change early, producing red leaves, while oak trees lag behind by a week or two, creating more brown pigments. Other species can produce yellow and orange hues.
“Trees are like people, they’re all a little weird, and each of those colors are a reflection of different ways that the tree has evolved and adapted to the environment,” said Rollinson.
A good time for tree maintenance
Though trees are already preparing for the winter season, Rollinson said it’s still a good time for maintenance. She recommends watering trees that still have green leaves, applying mulch to protect roots during the winter, and seeking help if a tree appears to be struggling.
“Now’s a great time to call an arborist so that they can come out and assess your tree while it still has leaves, and come up with that plan for the next year,” said Rollinson.
Though the transition period has already begun, it’s not too late to take in fall colors.
“If you’re willing to get out and explore, either in your neighborhood or at the Arboretum, starting from about now through, honestly, November, there’s usually color to see somewhere, because each environment and each species does something different,” said Rollinson.
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