When a tree has been removed, it may seem obvious to plant a new one in the same place.
That’s not a good idea, says Meghan Midgley, soil scientist at The Morton Arboretum: “That’s not likely to be the best place for your new tree to succeed.”
Once a tree has been cut down and the stump has been ground out, the site is basically a bowl-shaped hole full of wood chips.
Wood chips are not the right environment for tree roots, Midgley says. They won’t provide enough structure to anchor the tree. As they decay, the tree will sink. And new roots are likely to keep circling within the loose zone of wood chips, where it’s easy to find gaps, instead of pushing out into the soil where they need to go.
A healthy mature tree spreads its roots just under the surface of the soil for a surprising distance, often 30 to 50 feet or more.
“Your new tree needs a lot more space than the small circle you see where the old trunk was,” Midgley says.
It’s best to find a different location for your new tree, she says. If you must plant it right where the old one was, you will need to do some work to provide the right soil conditions.
First, remove all the wood chips from the hole and set them aside to use later as mulch. To refill the hole, purchase topsoil, not loose, fluffy potting mix, Midgely says. “You want to make the soil in the planting hole as much like the surrounding soil as possible,” she said.
Before you add the new soil, widen the hole as much as you can, at least a foot all around. Loosening a wide circle of the surrounding soil will make it easier for the new tree’s roots to spread out.
Cut and dig out any large roots remaining from the old tree to make room in the widened hole for the new ones. You don’t need to remove every root; smaller ones will eventually decay.
Remove the new tree from its container and position it in the hole. Mix the topsoil with the loosened soil from the hole as you fill in around the new tree. Tamp down the soil around the tree. Water the tree deeply.
Then use the wood chips from the old tree to spread an even layer of mulch 3 to 4 inches deep around the new tree.
For your tree planting questions and concerns, reach out to The Morton Arboretum's Plant Clinic.