Hello I’m Basil. I’m a Treecologist at Leaf & Limb and today we’re talking mulch. Mulch is an underrated, awesome way to improve the health of your tree. It’s easy to do, it’s free if you want to do it yourself, and it’s very simple. So let’s talk about a couple of important things.
First of all, why mulch? It provides a whole host of benefits:
- Soil moisture retention
- Regulates soil temperature
- Helps prevent weeds
- Helps prevent erosion
- Keeps the string trimmer away from your tree trunk
- Most importantly, it improves the health of your soil overtime.
That’s very important because trees grow from the soil. If soil is healthy, the tree will be healthy. Mulching is sort of like what happens naturally in the forest. Every year, leaves fall, twigs fall, and branches fall. The forest is mulching itself. In the suburban environment, we use mulch to recreate what happens in the forest.
One last really important thing is to not create a mulch volcano and we’ll talk about this more later.
I want to quickly run through four different mulch products I often recommend. Top on the list is a triple-shred mulch. It is aesthetically really appealing; it looks nice. It’s usually a continuous brown color, so if you’re managing a community or you have a really nice piece of property, it looks great. The only downside is that it’s not free unlike our second option: arborist wood chips.
Arborist wood chips are what are generated when a tree or branches are put through a chipper and blown into the back of a truck. Most tree services will give away wood chips for free. If they try to charge you something, just call the next tree service on the list. Most tree services need a place to get rid of their wood chips. Disadvantage: they don’t look as good. You might have a cedar tree chipped up alongside a maple, so you’re not going to get that consistent aesthetic functionality that you will from triple-shred.
We’ve also got pine straw. Pine straw is a popular option. I think it looks pretty good, it’s much cheaper than triple-shred. The issue is that pine straw, over time, doesn’t break down and provide that organic content for the soil that you get from wood chip products.
Finally are leaves. Leave are very underrated. They are what happen in a forest. They fall every year and that is nature’s mulching system. You really cannot go wrong getting a layer of leaves around your tree every year. I recommend even if you do mulch around your trees, get leaves on there every year. It’s just a great way to improve the organic content.
One little trick, if you like pine straw because of its aesthetics, which many people do. I recommend, pulling your pine straw back, layering arborist wood chips underneath so you’re getting the organic content that you need and then you can lay the pine straw back on top. So you’re getting the best of both worlds. Free wood chips underneath for the soil benefits and the tree benefits, and then pine straw on top for the aesthetic.
So I mentioned mulch volcanoes earlier. What is a mulch volcano? A mulch volcano is where you install mulch around your tree and you pile it around the base of the trunk of the tree. This what we call a mulch volcano. The problem is the mulch keeps moisture and it keeps the trunk wet. The trunk of a tree is designed to stay dry because it grows above ground. When it’s constantly staying moist, this leads to all kinds of health issues. More or less, you’re rotting out the base of the tree. It gets a lot more technical and a lot more complicated than that. There’s also the issue of roots growing in the mulch and strangling the tree. Don’t want to go into any detail with that, but I just want to say: don’t put mulch around the base of the trunk of the tree.
What you should do is keep whatever mulch product you use at least 2-3 inches away from the trunk and then extend it as far as you’re willing to go. If you can get it out to at least the edge of the canopy, that’s fantastic. Some people might not want as much, so I’d go least 3 feet, but the further the better. For a triple-shred product, 2-4 inches is great. For the arborist wood chips, you can go deeper if you’d like. You can go as deep as 12 inches providing even better weed control. It’s really just a matter of preference, but 2-4 inches is a safe number if you’re not sure what to do.
One big thing you’ve got to watch out for, especially with the triple-shred product is it becomes hydrophobic over time. This means on the top of the mulch, it begins repelling water. If this happens, you’re not getting water in your root system. The tree has to have water and now mulch actually becomes an enemy of your tree. It’s causing a net negative impact to your tree. So what you’ve got to watch for is if you see water running off the top the mulch when you’re watering or if you notice that the top of the triple-shred is looking crusty, go check. Turn it over, poke your finger through. Is it soft and loamy? Can you turn the mulch over or has a hard crust formed on top? If you’ve got a hard crust on the top, you’ve got to turn that mulch over. The easiest way to do this is with a tool called the potato hoe. It has three prongs that point down. Very easy way to just -- dig, pull, dig, pull -- Very easy to turn the mulch over. If you’re using a triple-shred mulch on one of your properties or in your community, rest assured that if it becomes hydrophobic, you need to schedule that mulch to be turned over at least once or twice a year.
In my book mulching is one of the best, easiest, potentially free ways to provide great benefits to your tree. I often tell people especially when they don’t want to invest in expensive soil improvement programs or fertilization programs or they are just on a tight budget, I tell them, look: you get free wood chips from a local tree service, spread it around the base of the tree, keep it off the base of the trunk, and go out as far as you’re willing to go. It’s a simple, awesome, easy thing to do for your trees.
That’s all I got for today. Remember, proper mulching makes healthy trees and happy people.