Why mulch your tree? It seems like a lot of extra work for a seemingly unimportant element. However, next to watering, mulching is arguably the best practice for newly planted or even older, established trees.
Here in Dane county our soils are generally high in clay which compacts easily and can make it hard for roots to respirate. Mulch helps remedy this.
Mulching benefits include:
- Decreased evaporation, allowing the soil to retain more moisture for the roots to uptake.
- Increased root insulation, keeping roots cooler in the summer and warmer in the winter.
- Allows for more gasses to the roots, which drives root respiration.
- Break it down! Organic mulch breaks down slowly over time and becomes rich Humus. Humus increases soil nutrients, in turn increasing soil fertility.
- Decreases root competition (don’t plant grass around the base of your tree!).
- Provides protection from lawnmower damage.
- Dang it looks good!
Always mulch 2-4” deep, never greater than 4” deep. Mulch that is too deep can inhibit oxygen in the root zone. Oxygen is necessary for roots to respire. Make sure you leave the root flare (base of the tree) slightly exposed, otherwise roots can grow in the mulch and girdle, or choke the tree. Think flat round mulch rings and avoid “volcano mulching,” or piling mulch up against the trunk.
The wider the mulch ring the better. We suggest 4-6’ or greater. Roots stretch wider than the canopy, give them room to breathe! It’s especially helpful to have a large mulch ring around young trees. The growing roots will thank you!
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 (pictured).
Medium to coarse textured materials work best, as fine material can pack down and retain moisture (eg: finely shredded bark mulch). Natural wood chips are always the safest bet and are free if you call us! Other organic options include grass clippings, leaves, and straw. Always make sure the mulch has been composted in order to kill all weed seeds. Avoid rubber mulches and rocks if possible.
Investing a few hours can help your tree for a lifetime. 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 [email protected]! Show off that beautiful donut.