Video | Mulch Volcanoes: Deceptively Deadly

Today we are talking about these piles of mulch! We call these Mulch Volcanoes. Many people think they look beautiful. Except the one little problem is… they kill trees.

Mulch Volcanoes seem like a great idea, I mean, you’ve got this lovely mulch. It looks good, it’s rotting, it's blocking weeds. All this good stuff. Except the problem is that they cause two big issues. First, it rots the trunk. Second, it makes roots choke the tree.

Let me show you what I’m talking about. So when this mulch is piled up around the base of the tree. It causes the trunk to stay moist, and that causes the trunk to rot. This trunk is biologically adapted to be dry.

The second big issue is that roots start growing in this pile of mulch, and they actually start strangling the tree. I’ll show you some examples right here. So I’ve been digging around the tree and I’ve excavated lots of examples where you can see these roots are actually growing around and strangling. This is the best one I’ve come across so far. This root goes halfway around the trunk, and keep in mind that there’s lots of other roots just like this one that are deeper below. These are all strangling the tree.

If you want your tree to live a long healthy life then you’ve got to remove this mulch volcano. Otherwise the trunk is going to rot, roots are going to strangle the tree and it is going to die over the long run.

So what does mean to remove a mulch volcano and how do we know when we’re done. Well the simple answer is, you peel mulch away from the tree trunk until you reach the point at which you can see what is known as the root flair. And that is basically where the trunk goes down and it starts to flair out turns into roots and those roots disappear going away from the tree. This is the root flair. We don’t want the telephone pole which is this. This is just a straight post that goes into the ground.

So if you want to try to do this yourself let me show you a couple of things. First, best case scenario you have a young tree that doesn’t have a ton of development, and in that case you can just simply rake that mulch away. You may come across some little baby roots like this, you can just snap them, or maybe they’re a little bigger, and you can cut them. No big deal, these are adventitious roots it’s not gonna hurt the tree. So that’s best case scenario you're digging down, you get down to the root flair. All is good.

Unfortunately after trees have been in the ground for a little while it's going to get a lot more complicated. Like, this is a great example here. This tree‘s been in the ground for a while. It is a situation where you probably need a professional, somebody who knows how to do this work. But this said let me just show you how I go about doing this.

So first of all, the name of the game is just getting down, and as we go down we are going to need to bring the layers with us. So here's this big root we encountered earlier. This one I’m actually going to cut it like so. And uh, if you want to swing around to the other side… alright so this one is a big root, we can make a cut, and we can start peeling it back. Now for some big roots we may actually need chisels which is the case here. If you’re horrified by this damage, it's... it's just how it is. We are going to be pruning all of this away.

You can actually see where the tree has actually grown over top of the root we just cut. I would expect this tree to be buried very very deep. I’m going to bet just based on experience, this thing probably goes down another six to eight inches and for a job like this we need professional tools. We need something called the air spade. Air spade blasts out air at a very high velocity. It allows us to actually get down and deep and expose roots and make cuts. It’s something that most folks will not have the resources to purchase on their own. But again to those of you who maybe are on a limited budget and you've got situation like this and you want to save your tree. Go for it!v

I recommend the Hori-hori. I recommend the mattock. You’re going to need lots of digging tools. You’re gonna need pruners, saws, and chisels.

Mulch is really amazing for the health of your tree if you do it right. That means don’t pile it on the trunk, spread it out maybe even to the edge of the canopy if you’re willing. Four to six inches deep is usually what's recommended. We have a separate video on this topic if you want to check it out. Key is this though, whatever you do just don’t make mulch volcanoes, because they will kill your tree.