INDIANAPOLIS – A critical sign of health throughout a tree’s lifetime is the base of the trunk where the roots spread into the ground. That part of the tree is called the flare. It needs to be kept dry and free of mulch and other materials, like leaves or soil. It is quite common to see mulch piled up on the bark of a tree by homeowners or even some landscaping companies.
“Too much mulch up the base of the tree keeps moisture in against the bark of the tree and that extra moisture can rot it,” said Elizabeth Jarvis, a certified DNR tree steward.
Jarvis helped to start The Great Hoosier Mulch Off last year.
“I belong to a group of tree stewards from the Department of Natural Resources. And we got a grant from Meridian Kessler Association and the DNR to do an outreach program,” said Jarvis.
Don’t mulch too high
They wanted to educate people that many trees are mulched too high. It’s often called piling it up like a volcano. There is a lot of information on ways to properly mulch.
If you can not see the base of the trunk where the roots spread into the ground, that’s not healthy for the tree. If your tree looks like a telephone pole, coming straight up out of the ground, it is asking for help. You need to have the mulch, leaves or soil removed until you can see the first major roots growing horizontally away from the tree. It can take a little time, but you can often do this yourself.
“Mulch less and remove old mulch first. Mulch is often applied every year, whether the previous application has broken down or not. This leads to material piling up against the trunk and covering the flare. If you don’t mind the appearance of old mulch, you can just fluff it up. It is a great opportunity to check the health of your tree’s flare. Maintain a total depth of mulch no more than 2-3 inches above the roots, never touching the trunk,” said Jarvis.
The root of the problem
There’s another problem when circling roots become girdling roots and will shorten the life of your tree. You may discover wayward roots in the mulch. You can remove fine fluffy roots, and you can cut a few if they are smaller than your thumb. If there are a lot of roots circling and touching the trunk of the tree, you should probably have a certified ISA arborist look at the tree. You may be saving your tree’s life and putting on less mulch will save you money.
Step by step
Here are some instructions for trees that do not have major roots growing up into the mulch: Use your hands or work carefully with tools. Also, try not to cut the tree’s bark.
First, carefully pull mulch off the base of the tree until you can see the soil. If the soil is dry, you may need to water to soften the soil before continuing. If you can see a nice flare, which is the top of the roots spreading into the ground, you’re halfway done. If your tree has no flare, that’s not proper care.
“Replace mulch in a ring, two to three inches deep and several feet wide. Mulching to the dripline which is the area under the tree in full shade at noon, is ideal. But it’s not always practical. Keep the mulch three to six inches away from the bark of the trunk,” said Jarvis.
Be gentle and pull any extra mulch away. Jarvis recommends cleaning your tools with wet wipes from one tree to the next because there can be disease causing elements in the soil that you do not want to take from tree to tree.
Bag or bulk?
One common question is should you buy your mulch by the bag or have it delivered in bulk? Much of that depends on how big of an area you have and how good you are at estimating the proper amount you need.
“Personally, I buy by the bag. An arborist I know suggests you buy it by bag because then you’re not going to get too much,” said Jarvis.
How deep is your tree?
Another healthy tree tip is how deep to plant a tree. Ground level is key.
“Lindsey Purcell at Purdue University likes to say, six inches too deep might as well be 6 feet too deep. When planting trees, they can come with a lot of dirt on the top of the roots. There will be little tiny roots, but you need to pull off the roots until you see some big roots. And the big roots are the correct planting level for the tree,” said Jarvis.
One final note about mulching is an easy way to remember how it should look when done right.
“They should look like how the trees grow in the woods. You’ll see that big flare. Somebody pointed out to me often times when children draw pictures, they draw them flaring out at the base. And that is the way they are supposed to grow,” said Jarvis.