Why, why, why!
Why and how the excessive use of mulch became popular is something I will never understand. I have seen mulch piled so high that it looked like an earthworks. Is the goal to protect the tree or plants from flood or invasion by a foreign power? Where has anyone seen this atrocity occur, in nature? My goal is to put an end to it (like my wish to stop young men from wearing their pants so low that they need to hold them up…).
Mulch is good
Mulch does some great things! Natural mulches (don’t get me started on the fake stuff!) help retain soil moisture, suppresses weeds, regulates soil temperature and over time adds organic matter back to the soil. Mulch is sort of like icing on a cake and can hide a lot of unsightly situations. It will give your project a finished look. Mulch creates a frame around your planting and gives grass a crisp edge. When applied correctly, the benefits are great!
Follow Mother Nature’s lead
Think about being in a forest and how the plants and trees are “mulched”. When the leaves fall off a tree, they fall almost straight down. Of course there is some movement caused by wind, but most of the wind is in the canopy of the trees, not near the ground. Most of the canopy of a tree is not near the trunk, so the leaves don’t pile up against it. Add that tree trunks are round(ish) and any wind will move debris around the base. In your yard, think about where the leaves pile up. It’s the corners, flat walls and fences that catch the leaves. On a prairie, the soil is built up very slowly because there just isn’t much organic matter added yearly and what is added, is very susceptible to being moved by wind.
Now consider the difference between fallen leaves and the products we call mulch. Leaves are thin, curved and bumpy, with loads of air space between them. Fallen leaves are not dense like mulch. Nature quickly breaks them down into a fine texture. This happens quicker in damp, shady places. This fast, aerated break down prevents the kind of problems we see with mulch. Mulch on the other hand is a wood product. Wood is dense and slower to break down.
Where mulch goes wrong
If your plants have been installed correctly (with part of the rootball above grade), an inch or two of mulch is fine, but only in between the rootballs. Mulch should NEVER, NEVER, NEVER touch the plant. “What?” you ask. Yes, you were taught wrong. In the section above, you learned that plants in a forest are mulched yearly by leaves, but it quickly breaks down and never lasts long near the crown plants. The crown is where the root system and the upper part of the plant meet. The crown of plants need light and air, plain and simple. When mulch is heaped up around the crowns of plants, it prevents light from reaching the crown and reduces the amount of air the crown gets. Light and air reduce moisture levels, which helps prevent disease.
Since we typically get ample amounts of rain, use our irrigation systems with mindless abandon and have heavy clay soils, large amounts of mulch can make a bad situation worse. The soil may never dry, creating dire conditions for some plants. There are some species that tolerate excessive mulch better than others. Some of the worst effected plants are grassy plants (iris, daylilies, liriope, etc.), Indian Hawthorn, Azaleas and Loropetalum. Over mulching is one of the most costly and common mistake people make. Landscapers are the worst about over mulching…ggggrrrrr.
A note on colored mulches. There are 2 ways to color mulch. Oil bases dyes are used commonly to color mulch. I constantly hear vendors say “It’s organic”. What a ridiculous argument. Well, the oil I use to fry chicken in is organic too… but I’m not going to pour it in my yard. The second way they produce black mulch is by adding soot, a by-product of some sort of industrial process. This “blackened” mulch is as alkaline as Draino and effectively suppresses weeds…and every other plant too. Repeated applications can make it impossible to grow anything.
What is right?
Yes, you can mulch your trees and plants, but only if you do it correctly. Only add enough mulch around your trees to just cover the soil. If you need to add another bag in 2 or 3 months, do it then. Your only trying to make it “pretty”, not replant the tree.
For your shrubs, mulch the soil that looks straight up to the sky, but not under the plant. The soil that is under your plants is in the shade and will dry slower than sunny spots. After a good rain, a little mulch will move under your plants. The only exception would be if you are seeing erosion and exposed roots. Then add only enough mulch to cover the exposed roots and address what’s causing the erosion.
For annual color, plant straight through the mulch. Do not add mulch after the fact, unless you plant each plant with only 1/2 of the root ball in the ground, even then be careful. Annuals are easily smothered.
If you hire someone to mulch for you, tell them exactly what you want done, you’re the boss. This can be easier said than done. After the job is done, check the work. If there is mulch piled around the crown, it will need to be pulled back. If your landscaper is still there, ask them again to fix it. If you have to do it, a kid-sized leaf rake is great for this job. If mulch is really stuck in the crown, you’ll need to get in there and remove it by hand.
Proper mulching is an art and a science, now go get and “A”.