It’s officially fall on the calendar and the onset of cold temperatures apparently is enough proof to start the leaves turning their fall colors. Department of Natural Resources Forester Randy Cook says the timing depends on what conditions we’ve had during the spring and summer.
Some of the yellow-colored leaves will start to show first, and you can already see that change in black walnuts, willow, and cottonwood. Later, in early October, we’ll see maples turning orange to crimson red. Most of Iowa’s oaks will simply turn brown, but Cook says there are plenty of other tree species that’ll put on a show.
The native green ash will turn yellow, some white ash will turn red, and an autumn-purple white ash that’s planted for its color turns a magenta-red color. For a trivia point, he says there are also some kinds of conifer that will drop their needles in the fall.
There are several varieties of larch, some conifers that aren’t evergreen, and some people have planted bald cypress brought from southern climates that do okay in a wet, sheltered southern exposure. And there’s a variety of “dawn redwood” that also loses its needles in the winter. Cook points out the show of fall colors is not guaranteed,, and in some years we’ve missed it almost entirely.
If it’s hot and dry from mid-August into September the leaves may just dry up, wither and fall without changing to much but brown. But he says we’ve had some good rainfall the last five or six weeks as and can count on some decent fall color. Now Cook says some cool, calm evenings with a little frost will also help trigger the change of color.