Real Gardens, Shut Up and Dig

A Tale of Two Mulches

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Which do you prefer on the garden floor: the varying texture of fallen leaves, or the fine-grained uniformity of wood chips?

When I began making this new garden, I was able to get large quantities of bagged leaves and grass clippings free, so I used them to smother the lawn and to mulch around new plants. This year, I found a source of cheap wood chips, so I am employing them when mulch is needed.

Mulching with the wood chips this spring has prompted two “ahas.”

First, though a mulch of leaves creates great soil filled with worms and other beneficials, I’m noticing that leaf mulch tends to become dry and hot at the surface during Boise’s hot summer months, when lack of moisture drastically slows decomposition, whereas a layer of wood chips keeps a noticeably cooler surface temperature and retains more moisture at the soil surface. Plants that are struggling in sunny areas of my new garden (even those with a deep mulch of leaves) have perked up when I added a layer of wood chips.

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One of my garter snakes naps on a bed of warm, dry leaf mulch.

This is different from my gardening experiences in Minnesota. There, mulching with leaves ensures cool, moist woodland conditions; they are the best materials for mulching trees and shrubs and their ground layer companions. Wood chips also keep the soil cool and moist, but don’t provide the nutrient boost given by leaves as they decompose.

My second “aha” is that I relax when a bed is mulched with wood chips. Is it that the wood chips are finer grained and more uniform than the widely varying “dinosaur poop” look of the bagged leaves? Is it that they smell fresh like a forest, rather than the mildewy or downright putrid smell when some of the leaves & grass clippings are released from their bags? Or am I responding to subtle signals of the plants, which are less stressed when mulched with wood chips?

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It’s easier to relax in the wood-chip-mulched garden.

Along with these ahas comes the not-new thought that, though I am a big fan of mulching, I view it as a temporary step in my garden’s evolution. Eventually, I’d like to achieve coverage of all bare ground with vertical layers of plants. Living mulch.

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The bed in the foreground is being covered with a living mulch of Marrubium rotundifolium (roundleaf horehound), Antennaria microphylla (rosy pussytoes), Artemisia versicolor ‘Seafoam’ (curlicue sage), and Sedum rupestre ‘Angelina’.

Posted by on June 3, 2015 at 2:36 am, in the category Real Gardens, Shut Up and Dig.
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17 responses to “A Tale of Two Mulches”

  1. susan harris says:

    I also prefer living mulches and have never used wood c hips – just free leafmold and some bagged fine pine chips.
    I don’t like the look of drying leaves – to my eyes, messy, untended – and they blow away. Plus many leaves are too large to break down quickly, and tend to matte and block water from percolating down.

    • Frank Hyman says:

      I’ve been having great success with shredded leaf mulch. A cordless mulching mower makes the work quiet and not messy. They look great, don’t blow away and are easily loaded in the wheelbarrow and spread with a pitchfork. And I don’t have to bend over to put leaves in a bag, etc.

  2. Jason Doran says:

    This mirrors my experience living in the high desert and speaks to the need for localized expertise as opposed to the sweeping generalities often found in garden help commentaries.

  3. Deborah hudson says:

    This does show the diversity of climates with diverse needs. I like alternating the mulches and plants, like farmers in the areas ( my father) alternate their crops to enrich the soil. If we did not alternate the mulches and soil in this high dessert, it would be sage, sparse wild flowers, grasses, and a few junipers.

    Not only the mulch, but ricks for shade and soil retention help make our gardens lush. Also as you point out in hell strip gardening, lots of plants together help each other grow and thrive also, and add natural beauty. We don’t need to continue the bare look!

  4. anne says:

    There’s that Sedum “Angelina” again!

    I’m apt to put any fallen leaves that I corral into my compost rather than on my beds, because I like the “brown” layer between my food compost layers. I do use bark mulch and compost in beds that are newly-planted and/or publicly visible, just because it looks “neater”.

    I’m fascinated by the notion that you feel more relaxed depending on the type of mulch. I guess if it’s more aesthetically pleasing, that might be a factor–it just feels better to you? Or maybe it’s that you can better see the snakes and other creepy-crawlies coming 🙂

    Your garden is looking sooo nice, Evelyn–thank you for sharing it as it develops!

  5. Anne Kiselewich says:

    We always used bark chips for mulch when we lived in CA. That was a very popular mulch out there. Loved the fragrance of the wood chips.

  6. Ryan Hogan says:

    I prefer shredded pine bark mulch. It’s not always available and it’s not the cheapest. I find it’s the easiest to garden with, improves the soil, and I like the look of it.

    I’m not crazy about wood chips. It’s fine around shrubs and trees, but it’s hard to garden with around perennials and annuals. Some of the “color enhanced” mulch looks radioactive, anything but natural. Not a fan.

    I think gardening with shredded leaf mulch would be great, but requires storing leaves, having a chipper/shredder. I’ve tried using the lawn mower. It works, but it makes a mess and who has the patience? Interesting points about how the same mulch behaves differently in different climates.

    • A. Marina Fournier says:

      Oddly enough, I was never able to smell either the wood chips nor the gorilla hair used in my Santa Cruz garden.

      While Ryan prefers shredded pine bark mulch, I prefer the same in cedar or redwood (although I can’t be sure that first-growth redwood isn’t in there). I find the shredded mulch is easier on feet, and more attractive to *me*.

      I always refer to the alpine strawberries planted under trees and shrubs in planters or half-barrels as mulch. After all, in the modest frosts we get in the flatlands of the SF Bay Area, the Alpines are not likely to worry about them. If you’re going to grow them for dessert-making, you need LOTS of that ‘mulch’ planted, and better it be if the snails or slugs have a hard time getting to them.

  7. Mischelle says:

    I live in Pennsylvania- translation: Penns Woods – in a heavily forested area, so it’s leaf mulch for me. For years we raked leaves out of beds, threw them in the woods and laid down double shredded bark mulch. I liked the uniformity of the fine texture and dark color.

    In an effort to garden more sustainably a few years back, we decided to start using our leaves as mulch. We still rake them out of the beds (thanks to the abundance of the leaves that roll off the ridge above us). But then we run them through a shredder to reduce them and place them back into the beds. I have to say I really like the look – especially considering my forested location.

  8. Cathy says:

    Would it be possible to combine the best of both worlds? Do a layer of leaf mulch for the rich soil and then do some wood chips on top for the moisture? The wood chip topping might also help keep the leaves down on the ground where they should be.

  9. Cathy, I like that idea, and that is just what I’ve done — building soil by smothering lawn with leaves initially to make a planting bed, then planting, and now topping with wood chips. Using diverse materials will also add diverse nutrients to the soil, as Deborah mentioned. Of course, I would hope to transition then to living mulches of diverse plants that enrich the soil by dropping leaves periodically, fixing nitrogen, aerating with their roots, etc.

  10. Elizabeth Zagorski says:

    Here in Hokkaido, I use birch leaves, a free gift from my birch trees. They are small and break down easily. In places where too many fall or end up due to wind, I reditribute.

    In early spring the flowers of Adonis amurensis look so charming peeping through the fallen leaves.

  11. Eliz. says:

    I love mulch discussions. There is always more to discover. Though, ideally I always long for a time when I can use less of it.

  12. Beth says:

    I researched, observed and thought about this issue quite a bit last year, and came to the following conclusions: I think wood chips work nicely around shrubs and trees, which makes sense, since they naturally grow in places where twigs and bark from other trees in the forest would naturally mulch them. They can be added whenever more are needed around shrubs and trees, year after year if necessary. Around perennials, I also think wood chips work better in a newly planted area to repress weeds and retain moisture for plants while they establish themselves, much better than leaf mold, which I think is better to work into the soil before planting an area. But after the perennials have established themselves (perhaps after 2-3 years), they are more able to find water with their deep roots and have filled in to crowd out weeds, so an annual topping up with leaf mold is much better for the soil than wood chips, which can form a non-permeable crust if added annually. I live in Iowa, which is probably more similar to MN, your former home, so perhaps this is not so applicable to your situation…. Thanks for bringing up this important topic! -Beth

  13. Emily says:

    Ok, I’m a newbie and I have a newbie question. One of the big reasons cited to pull weeds is because weeds “steal” water, nutrients, etc. from the plants we want to grow. Why wouldn’t a living mulch do the same thing? I’m just really curious where the difference is. Is it simply that we pick a desirable plant (so, by definition not a “weed”) to share the water, nutrients, etc. with the other plants? Or we pick less thirsty ones to keep out more aggressive weeds? Or is it more about getting into the nuances of companion planting? I love the idea of vertical planting. It just seems to go against conventional wisdom re: weeds, competition, etc., at least on the surface.

  14. Veda Petrovich says:

    Just remember that shredded mulch tends to get so tightly compacted that it
    acts like shingles on a roof. It won’t let any rain in to the soil. So every so often
    you need to take a pitchfork and loosen up the mulch so that water can penetrate. I see this problem on a lot of commercial sites and it makes me crazy.

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