Tree volcanoes
Tree volcanoes never go away so it’s a good idea to keep harping on it until they do. Just last Thursday I was top-dressing and over seeding new lawns. This is a normal spring project. As temperatures rise and soils warm-up, we add soil to weak lawn areas and then over seed them.
Now, as I went along, I noticed a small maple tree with a volcano pressing against it. See the picture below. I removed the soil until I could feel the root flare. That’s where the trunk ends and roots begin. Anything above the root flare shouldn’t have any soil piled up over it. Here’s why.
Say no to volcanoes
Piling up soil or mulch against the trunk will lead to wood rot because these tissues aren’t supposed to be covered with soil. And rotten wood can invite disease into the tree. All you need is one fungus to get in and you can write off the whole tree.
Once I have also seen new adventitious roots develop from the trunk because it was covered with soil. If you allow those roots to get bigger, they can circle in the volcano and potentially girdle the tree.
Think donuts
To properly mulch trees, it helps to think of donuts. First, install new mulch and soil in your tree well. Second, find the root flare and make sure the soil doesn’t go above it. Third. taper your soil down to the outside edge. This way most of the soil will be in the middle zone, thus giving us the desired donut shape. I learned this from my mentor Dr. Linda Chalker-Scott. Below is a picture of my soil install from last week.
Do you see the donut shape? The root flare is nicely exposed and the basin will collect water nicely. The outside edge has a shallow deep edge and the soil is nicely tapered down to it. Notice how most of the soil is in the middle, not piled up high against the trunk. Think donuts, not volcanoes. Donuts are good, volcanoes bring danger.
