Whether you have a newly planted tree or a mature tree in your landscape, laying down a thick layer of mulch is a wonderful yearly practice that can dramatically improve the health of your tree long term. This guide will walk you through the benefits of mulching, how to do it right, and the best materials to use for optimal tree health.
What is Mulch & Why Should You Use it?
Next to watering, mulching is arguably the best practice for keeping newly planted or even older, established trees healthy long term. Mulch is an organic material spread over the soil surface to protect and nurture tree roots. It helps moderate soil temperature, retain moisture, and improve soil structure as it breaks down.
Aside from the improved aesthetics of a well placed mulch ring, here are some of the other benefits of mulching around your tree:
- Moisture Retention: Covering the soil helps it retain more moisture for the roots to uptake.
- Root Insulation: A layer of mulch moderates the temperature of the roots, keeping them cooler in the summer and warmer in the winter.
- Improved Soil Aeration: Mulch allows for more gasses to reach the roots, which improves respiration.
- Soil Enrichment: Mulch breaks down slowly over time and becomes rich humus. Humus increases soil nutrients and organic matter in the soil.
- Reduced Root Competition: You don’t want grass and other plants popping up at the base of your trees because they compete with the tree for water and nutrients (and often win!).
- Protection Against Physical Damage: If you walk around any city or town and look closely at trees planted in grass you’ll notice that many of them have wounds low down on their trunks from being run into with lawnmowers and other equipment. A nice, wide mulch ring will ensure you never accidentally run into your tree causing damage.
Mulch the Right Way
Choosing the Right Mulch
When choosing the type of mulch for your trees, we recommend using medium to coarse wood chips. Avoid using fine materials (eg: finely shredded bark mulch) because these materials can pack down and inhibit water from reaching the roots.
Wood chips are available for free in many municipalities. If you’re having tree work done on your property, you can request to have the woodchips dumped in your driveway. If you have many trees to mulch and a big garden you could sign up for a service called Chip Drop. You submit your name to a database that tree care companies can search when looking for somewhere to get rid of a load of wood chips. Our dump trucks fill up several times a week and we’re always looking for places to deposit woodchips and clear out our trucks for the next job.
Once you have your load of wood chips and are ready to mulch there are a few tricks and tips to keep in mind for applying mulch around a tree.
Mulch Depth
Always mulch 2-4” deep, never greater than 4” deep. Mulch that is too deep can inhibit the oxygen exchange that needs to happen between roots and the atmosphere. In other words, roots breathe oxygen just like we do! Most of the roots of a tree are located in the top 6-24 inches of the soil, so make sure you’re not covering them up with too thick of a layer of mulch.
Spread of Mulch Ring
The wider the mulch ring the better. We suggest 4-6’ or greater from the trunk of the tree. The farther out you can spread the mulch ring the better for the tree because the less the roots have to compete with grass for water and nutrients.
Roots stretch wider than the canopy, so give them room to breathe! It’s especially helpful to have a large mulch ring around young trees. The growing roots will thank you!
Make sure you leave the root flare (base of the tree) slightly exposed. Aim for flat round mulch rings, like a donut, and avoid “volcano mulching,” or piling mulch up against the trunk. More on that later.
Creating a Natural Edge
We suggest a natural edge. If you dig a 2-4” deep trench around the outside of the ring, the mulch will naturally fall into it. No need for plastic edging!
In fact, when roots hit the plastic edge they interpret it as a barrier, and begin growing in a circle. This can lead to girdling roots.
Avoid Volcano Mulching
While walking around your neighborhood or town you might notice the strange phenomenon of people creating tall piles of mulch around their trees, or what we like to call “volcanoes”.
This great illustration from Trees Louisville shows the difference between a mulch ring and a volcano.
As you can see in the first illustration of proper mulching, the mulch is pulled away from the base of the trunk. You can build it up a bit higher around the perimeter in order to create a basin for the water to infiltrate the soil. The picture on the right illustrates the shape of the volcano style of mulching. This practice traps moisture against the bark, promoting rot and decay, and creates a haven for pests. When you’re mulching your trees, aim for a “donut” shape, with the mulch pulled away from the trunk and slightly higher at the edges to form a water-catching basin.
If your trees have experienced excessive mulching in the past, your tree may be experiencing challenges like reduced nutrient flow and poor water infiltration. Our team at Eco Tree Company offers root and soil remediation services to address these past issues so your tree can continue to thrive.
Your Tree’s Best Friend
Investing in mulch and taking the time to apply it correctly can significantly impact the health and longevity of your trees. It’s not just about aesthetics; it’s about creating an environment where your trees can thrive.
Did you make a beautiful mulch ring? Neighbors might find it strange to get excited over a mulch ring, but we get it! Email us a photo at office@ecotreecompany.com and show off that beautiful donut!
