Despite drought, expert says fall is good tree planting time
Bur Oak tree (Iowa DNR photo)

DES MOINES — A tree expert in the Iowa Department of Natural Resources says the abnormally dry conditions throughout the state make this fall a good time to plant a tree.

“I really like planting trees in the fall, especially when we have years like this past year with drought conditions,” says Emma Hanigan, the urban forestry coordinator at the DNR. “This gives them a little bit of a leg up when they’re going into spring.”

That’s because after a tree is planted, it gets watered and Hanigan says there are a few more weeks of watering left on the 2022 calendar.

“Then some of that root system will be established going into spring and that can be really helpful in a drought season as we know it’s very difficult to keep up with watering,” Hanigan says. “We still need to water our fall trees the following summer. However, they might have just a little bit more establishment going into that season.”

Root systems are critical to the long term health of a tree over the coming decades. Hanigan says people planting trees in their own yard are typically planting a tree that’s in a container.

“With those type of trees we see two common issues related to the roots that end up showing up 30 years if planted correctly,” Hanigan says, “and that’s circling roots are not corrected at the time of planting or they’re planted too deeply.”

The roots of trees grown in containers often hit that hard pot and then start circling the container as they grow. Hanigan says if those circling roots aren’t pruned at the time of planting, the tree will likely suffer.

“As the tree grows and the roots expand, that can cut off all the water and nutrients to the tree later on when it’s much larger,” she says. “…We like to not cut off too much root system, but in this case we really recommend taking off anything that’s encircling because we know that will ultimately kill the tree later on and we will sacrifice just a little bit of vigor when the tree is young just for that long term survival.”

Pruning that outer half inch or so of circling roots with a shovel or handsaw ensures the roots will extend horizontally from the base of the tree as it grows.

“Another option is to look for stock that is not grown in a hard pot container,” Hanigan says. “There is technology out there
that has bags or root-pruning containers that help this issue by pruning the roots through the air, so you can look for that technology as well, or go with a bare root style tree.”

The other major issue to consider when planting a tree is to get the triangle of roots deep enough in the hole. Hanigan says when shopping for a tree, keep an eye out for what she calls the “root-to-shoot” ratio.

“Having as much root area to top growth is going to give you the most vigor in your new tree and reduce plant shock,” Hanigan says, “so if you’re looking at a container and it has a very large container and a shorter tree, that actually is going to be a better tree at transplant time than a tree with a lot of leaves on top in a small pot.”

Hanigan says Iowa is overpopulated with maple trees and she’s encouraging Iowans to plant other species. The Iowa DNR’s website has information about a residential tree planting program.