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The days of weedy, bare soil gardens are over. Here’s the science behind why you should use mulch in your garden AND how to use it correctly.  

People often ask us, “If you could only give one gardening tip to a new gardener, what would it be?”

Frankly, this is an impossible question to answer because gardening is a holistic, not a reductionistic, endeavor. There aren’t any magic pills, foliar sprays, or wizard spells that you can apply to make everything “work.”

The reality is that your garden is an ecosystem, and like any other ecosystem, all the parts are integrally connected, like gears in a watch.

However, non-answers are not what you’re looking for, so we always try to provide an actionable response to the “one tip” question. Drumroll…Here it comes…Wait for it…

You should use mulch in your garden.

“Huh? Mulch? Why?” You might be asking…

Why you should use mulch in your garden

Soil is a living system that serves an essential foundational function in our planetary system (and in your garden). It functions like your skin.

Scrape off the skin on your arm and a scab will soon form to start the healing process. Plow the “skin” of the earth, and weeds (nature’s scabs) will soon appear to start healing the open wound on the earth’s living skin (the soil surface).

Weeds are an early stage in ecological succession. “Ecological succession” is the term used to describe how nature is always trying to restore mature ecosystems, typically forests. 

Yet repeatedly plowing and leaving your soil exposed to the elements is how we’ve been taught to garden and farm.

A new, better gardening and farming paradigm 

What if you could design your garden in such a way that you didn’t have to plow, fertilize, water, or pick weeds? After all, those are the activities that make traditional gardening (and farming) time, cost and labor-intensive, right?

Well, let us introduce you to one of our best gardening friends that can do almost all that work for you: mulch.

Nope, mulch is not a magic pill, but we’ve found that applying 4-6″ of wood chip mulch on top of our garden beds in the spring and again in the fall produces results that are almost as good as magic. (Note: we “top-dress” the mulch on to the surface of our garden, we NEVER plow it in for reasons we’ll explain below.)

Mulch can also be free. Simply call a few nearby tree service companies and ask them if they could drop off their ground wood chips anytime they have some available.

As it turns out, they often have wood chips that they’d rather deliver to you for free than have to pay a drop-charge at the local landfill. Everybody wins!

The Data – What Does Mulch Do In Your Garden?

How does mulch work in your garden?

If you’re a soil geek like us, feel free to read the full, detailed meta review of the scientific studies about mulch conducted by Washington State University and published in The Journal of Environmental Horticulture. If that’s a little more than you want to dive into right now, read below for a summary of their findings…

The proven benefits of top-dressing your garden with mulch include: 

  • Improved soil moisture
  • Reduced soil erosion and compaction
  • Maintain optimal soil temperatures (wow, up to 50 degrees F in some extreme environments!)
  • Increased soil nutrition
  • Reduced salt and pesticide contamination
  • Increased binding of heavy metals
  • Improved plant establishment and growth by: a) Improving seed germination and seedling survival, b) enhancing root establishment and transplant survival, c) increasing overall plant growth performance;
  • Reduced disease
  • Reduced weeds
  • Reduce watershed pollution
  • Reduced pesticide needs
  • Aesthetic improvement (*as the researchers stated, it’s much harder to quantify this benefit, but let’s face it: rows of exposed plowed dirt are ugly; mulched beds with edible plants makes a much more attractive landscape)
  • Substantial cost savings (less inputs, higher plant survival rates, less plant maintenance, larger crop yields, etc = big $savings)

Yes, this is a rather long and substantial use of mulch benefits! 

If you use mulch in your garden, does it create any problems? 

Short answer: no. Assuming you’re using un-treated, non-contaminated wood chips. 

Mulch myths… 

But in case you get the same questions we do from people who can’t believe how good mulch is for your garden, it’s also important to note that contrary to popular belief, researchers found that top-dressing your garden beds does not NOT cause:

a. Soil acidification 

Even when using highly acidic pine bark and pine leaves, no increased soil acidity was detected. How? By the time the microbes convert these materials into soil via digestion, the acidity is neutralized.

b. Soil nitrogen deficiency

Yes, if you till mulch into your soil, it will cause a temporary nitrogen deficiency. Be sure to only place mulch on top of your soil rather than plowing it in. Let the soil organisms be your “plow” and bring the nutrition into the soil for you as they digest it. 

c. Spread plant diseases

Nope, the study found that mulch does not cause disease transference in instances where diseased trees were made into mulch

d, Attract termites

No, mulch does not attract termites. In fact, researchers found that mulch reduced termite populations, and, in one study, even increased their mortality rates.

Lesson: Start Mulching Your Garden Now!

Our favorite mulch is free mulch in the form of wood chips. Tree service companies in your area likely have an abundance of it, and might be willing to drop it at your home for free or for a small drop charge. Call and ask! 

The absolute ideal mulch contains all parts of the tree: leaves, branches, bark, and core wood. This course medium allows for maximum water penetration and retention, an ideal balance of “greens” and “browns” (nitrogen and carbon), plus it doesn’t blow away or compact during heavy winds or storms.

However, we don’t shy away from using fallen leaves or grass clippings as long as we know they came from lawns that have not been treated with pesticide and herbicide applications. Green living mulches (cover crops) are also excellent, although you will likely have to pay for seeds and won’t be able to plant much in your beds while the cover crops are growing.

Key Takeaway: Start using mulch in your garden today!

Happy Growing!

Aaron @ GrowJourney