Why You Should Heavily Mulch Your Garden

jasonvivier

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Hi all, I wanted to share my recent article on the topic of mulch. #clearlyverycool

Most gardeners generally misunderstand mulch. From what I’ve observed, mulch seems to be mostly used for aesthetic purposes- to keep weeds down and contribute a neatness and conformation in the front of the home, usually around perennial shrubs and trees. There is this commonly held misconception that arborist woodchips, and to a lesser extent mulches in general, carry pests, diseases, and are a fire hazard. The Autonomous Gardener is here to tell you otherwise.

Let me start by saying that I cannot recommend the use of rubber woodchips. One way to insure that a small outside BBQ fire spreads uncontrollably is to mulch with rubber. It generally isn’t the flame that makes extinguishing these fires a challenge, but rather the fact that you cannot even see the flame through the black thick smoke. So, from here on, when I reference mulch, understand that I am only advocating the use of organic vegetative material (organic as in not synthetic.)

In addition, I do not generally recommend landscaping woodchips that can be purchased in the store as a mulching material. Truly your best bet is arborist woodchips as the perks of using this material are twofold: first, they are generally free. Ask any lawn care specialist or tree arborist if they would rather dump them off at your house instead of paying to drop them off at your local transfer station. Second they are dye-free and could potentially already carry beneficial microbes. Personally, I prefer the aesthetic of natural chips to those strange colored chips that look totally alien in your natural forest garden!

There are four primary reasons to heavily mulch your garden: fertilization, protection, hydration, and pest control.

Mulch makes your soil a free fertilizer: Next time you walk through a forest, take a look around: who is fertilizing the forest floor? Not humans! When you look at the deep deep forest floor, you’ll immediately see mulch is everywhere. In many cases mulch layers have been building for tens of millions of years. Mulch provides nutrients to the forest and, given the history of the forest, have been a sustainable means of fertility of tens of millions of years. And the beauty of the forest mulching system is that, in a short time, ‘so can you!’

In a forest, the process of mulching begins when a tree limb falls or autumn separates deciduous leaves from the trees. Microbes and bacteria begin to reach up from the forest floor and devour the fallen material that has rained down from above. Additionally organisms (like worms) eat the bacteria. The excreta (yes, I do mean poop!) from all of this activity is functionally compost, sometimes called castings. Castings are the most effective soil amendment you can purchase for your garden. By mulching, you save the money you would spend on expensive soil amendments and fertilizers by growing and producing them onsite.

Mulch protects your soil: In addition to being a fertilizer mulch also protects the soil from solar radiation. Just like human skin, soil is susceptible to the effects of solar radiation, and can basically get a sun burn when left without anything to cover it up. This leads to degradation in the quality of your soil. Soil that is dry also tends to get blown away, causing less than healthy plants that then require fertilizer and also erodes away your soil. If you don’t mulch you end up with less soil and poor soil that costs money to replenish.

One other neat feature of mulch is that it disperses a load. When heavy feet fall on mulch it becomes less compacted than uncovered soil. Softer, less compacted soil leads to healthier plants, as the nutrients are able to freely flow through the soil to plant roots.

Mulch provides hydration: Despite what you might think, getting plants the water they need can actually be complicated. I like to say plants don’t need to be watered, they need to be hydrated. Again, think back to your last trip into the woods: were there any humans out there with watering cans, keeping it all lush and green? No! Why? Woody material, like arboreal mulch, is porous and stores water well.

When mulch covers the soil it is fed on by bacteria and those bacteria become food for other lifeforms. Those lifeforms work their way through the soil and leave behind empty spaces in the soil which not only makes the soil lighter but also gives water a space to pool. Thus, mulched gardens require much less water; in many climates, like mine, they do not require any watering at all.

Mulch as disease and pest control: Well hydrated and fertilized gardens yield healthier plants, which are less likely to suffer from pests and diseases. Mulch also prevents what is known as splash back. Splash back is what happens during a rain event when soil splashes up and lands on the underside of plants. This splashing can lead to rot, fungus and mildew issues on plants.

As a pest controller many small predators love to lie in wait in mulch and will handle many pests quite effectively.

The question is asked “wont mulch bring in diseases into my garden?” The answer here is generally no. In a majority of studies it has been found that the bacteria in diverse mulch are a majority of composters not pathogens.

Some cautions and things to consider:

Mulch shouldn’t be mixed in with the soil. It should be placed on top. Mixing mulch with the soil can lead to something called nitrogen lockup. Nitrogen lock up is generally when soil has ample amounts of surplus nitrogen but it isn’t plant available, leading to a nitrogen deficiency in plant bodies.

When planting seeds in mulch temporarily move the mulch aside, lay down your seed and cover with soil. After the plant has sprouted return the mulch so that you don’t have to water it. I personally use shredded fall leaves and worm castings for my direct seeded starter mix.

Keep your mulch diverse; don’t use all one species of wood chips, don’t use all grass clippings. Remember, too much of one thing in one place called pollution. The more diverse your mulch is the more diverse the nutrients in your soil will be. Different plants accumulate different nutrients in higher quantities than others. An example is the Jerusalem Artichokes which accumulates a fair amount of calcium and magnesium. This makes it ideal for mulching beds used for the cultivation of cucumbers as they require those nutrients. But even better is to have soil with balanced nutrients and let the mycorrhizae take care of the rest. Because that is what they do! Wait!?!?! What is this mycorrhizae thing you speak of?

Let’s talk mushrooms:

Mushrooms grow out of mulches and that is okay. Mushrooms are the fruiting body of mycelium and are used for reproduction. Mycelium are the natural decomposers in the forest. Additional mycelium that are mycorrhizal actually break down materials into plant available nutrients and feed those nutrients to plant roots in return of carbohydrates that plants get via a process of photosynthesis. This is known scientifically as the mycorrhizal association. In many cases even you can inoculate your soil with edible mushrooms, but remember many mushrooms kill and you shouldn’t ever eat one unless you have positively identified it with 100% accuracy.

The Myth of pathogenic woodchips: http://puyallup.wsu.edu/wp-content/uploads/sites/403/2015/03/wood-chip-pathogens.pdf

Mycorrhizal Effects on Host Plant Physiology: http://aggie-horticulture.tamu.edu/faculty/davies/research/mycorrhizae.html

This is an old site and looks very 1992 but really has everything on the topic of mushrooms. http://www.gmushrooms.com/info.htm

Thanks and take care.
 

henless

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Lots of good info. Thanks!

I'm starting a new garden this year and using leaves for my mulch.
 

henless

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@Beekissed ~ Thanks for the link. Looks like the leaf mulch did better than the wood chip mulch. This gives me hope that my garden will do ok. I'm sure they would break down better if mulched, but right now I don't have a way to mulch them. I figure whole leaf mulch is better than no mulch.
 

Smart Red

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Actually, @henless, the whole leaves may clump and can prevent water from penetrating the leaf layer and reaching your soil. It will also provide a great hiding place for pests such as slugs and earwigs.

Shredding leaves isn't all that hard if you have a lawn mower. You can drive the mower back and forth over the leaves until they are in tiny pieces. I put the leaves on the driveway first, then run over them so collecting the shredded leaves is easy-peasy when I'm done.

Just an idea. There is no worst way to garden/no best way. Each of us gardens a bit differently from the others and, indeed, differently one year to the next. Adding leaves is better then not adding leaves and mulching is better then not mulching.

Gardening is, for me, and adventure every year. I'm happy that you're joining in the adventure.
 

henless

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Mowing my leaves is what I did last year when I bagged them up to put in my chicken coops/runs. So much easier than raking them up! The housing on our lawn mower is broke and we haven't had it fixed yet, so I'm gathering leaves by rake.
 

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