Leaderboard Ad

Tuesday, November 20, 2012

Stoned in the Garden: The Case Against Stone Mulch

Good soil conservation practices should start in our own backyards.  This post is my take on a futile and frustrating mulching practice that persists for no reason other than that it briefly looks nice.

Some folks might assume because I’m a geologist that I’d be a fan of stone mulch on the landscaping beds around my house.  When we purchased our house eight years ago, I found it to be a novelty that one of the previous owners had put down stone mulch on all of the beds.  My opinion of stone mulch has grown over the past eight years.  From neutral to What the hell were they thinking?!?!?

Starting two years ago, I’ve been gradually trying to reclaim our landscaping beds, one bed at a time.  Two years ago in order to plant our butterfly garden in front of our house, I raked and shoveled dozens of wheelbarrows full of the three-quarter- to one-inch diameter stone out of the front bed and started a pile of the unwanted gravel at the end of my driveway.  Last year, I reclaimed a bed on the side of our deck to plant an herb garden.  This summer I reclaimed a few other beds around our deck and patio.  And last Saturday, after spending six hours engaged in mind-numbing and back-wrenching raking and shoveling, I knew that blogging about stone mulch was probably the only thing I could do to ease the frustration of how much of my free time I’ve invested over the past two years trying to rid my landscaping beds of the scourge of decorative crushed stones.

Why Bother?
Any pragmatic casual gardener who reads this rant will undoubtedly think, “Why bother?”  Fair question, my casual gardening friends; however, I consider myself more than a casual gardener.  I consider myself a deliberate gardener.  Before I grow too old and weary to do anything more than tend my vegetable garden, my goal is to have nearly all of my landscaping beds covered with native perennials that I will not have to tend year after year.  I want my beds to be brimming with perennials so that there won’t even be any bare ground showing that will need mulch, and thus no bare ground for weeds to come up among the expansive native perennials.  I can dream, can't I?

Drawbacks to Stone Mulch
Here are the drawbacks to stone mulch that might not be very apparent when someone is getting a sales pitch from a landscaping contractor.

Plant matter that falls into the spaces between stone mulch
decomposes into soil and gives weeds a growth substrate.
Weed fabric is installed on the bare soil before the stone mulch is laid down.  That might sound like a fool-proof way to weed-proof, but I’d estimate it’s good for five years tops in a temperate climate.  After five or so years, stone mulch accumulates enough leaf matter falling from above to develop brand new soil in the interstitial spaces between the stones.  Then you get weeds growing in the new soil between the stones and sending roots down into and through the weed fabric.  Weeds can’t grow up through the weed fabric from below, but both water and weed roots can get through from above the weed fabric.

My other big gripe with stone mulch is that it’s very arduous to plant anything in it.  In a bed with organic mulch and a weed fabric, it’s no big deal to dig in with a spade and make holes for bulbs or plants.  Planting in stone mulch requires extensive raking to clear even a small patch in which to penetrate the weed fabric and reach the underlying soil.  I would imagine that even casual gardeners would become frustrated by the difficulty inherent in trying to plant anything through two or three inches of stone mulch.

The way it should look.
And of course, when using stone mulch, your beds are not getting the benefits of organic mulch such as:  returning nutrients to the soil, maintaining soil moisture and temperature, and blocking light from the soil to prevent weed seedlings from becoming established (sunlight can partially penetrate into the spaces between stone mulch).  In addition, beneficial critters like my toad friends cannot burrow through stone mulch and weed fabric to hibernate for the winter. I want to do everything I can to encourage natural insect controls, like toads, to live in the beds around my house.
This is one of my toad friends that lives under our deck.
 The Rest of the Story
I still have a lot of work ahead of me in my battle to reclaim my landscaping beds from stone mulch, although I’m quite pleased with each individual bed that I reclaim.  I’m less than halfway through the battle, but I’m hoping it doesn’t take me another two years to finish.  Actually, the biggest problem I’m facing right now is what to do with all of the stones I’ve removed thus far and have yet to remove from my beds.  I estimate I’ve got about a four-ton pile so far. I’m open to suggestions, but I’m guessing I might have to resort to Craig’s List.
Any takers?


  1. Decorative stone has many advantages when applied to near house beds. Water moves away and is not trapped next to building materials. It does attract vermin as much as rotting wood fibers do. Less maintenance with proper installation.

    Good luck spending countless mind numbing hours pulling weeds, constantly adding new mulch and attracting pests and vermin to burrow and invade your home.

    Decorative stone applied to proper depth, proper underlayment, leaf blower removal of residual clippings and leaf litter with a touch of herbicide, will provide many years of maintenance free service.

    Sorry for the dissenting opinion but to each his own.

    1. It's 3 years since your comment. Is your gravel yard still low maintenance? My neighbor did the same thing 5 years ago but her landscape fabric is now degrading and more weeds are getting established.

  2. Good thought. Though it is an opinion of look, and might have soil stabilizing qualities where acidic soils disallow tree growth. Still, some gardeners and gardens do best with native plants and soils. So one has to think /decide...whether to have a native garden and return all wildlife, or promote the depot-driven sales of invasive plants and materials in your yard?

    A bigger problem than stones (at least in my mind) exists with the nitrogen based fertilizer boom. While some counties have disallowed the spraying of fall/winter solution anymore, I believe spray lawn chemicals should be banned altogether. I personally do not care if squashing the chemical application companies loses any local jobs; maybe those applying and selling the crap might rethink the short and long-term affects on their local watershed and environment. -Bill

  3. Thanks for the comments. Dissenting opinions are welcome. Regarding the vermin issue, we've had problems with mice prior to transitioning to organic mulch, so the stone mulch doesn't seem to have deterred them significantly. And I never had success with my leaf blower on the stones. On the low speed, about half of the residual clippings would get stuck between the stones. On the high speed, it would blow the stones out into my grass. But thanks for reading.

    And yes, Bill, sprayed lawn fertilizers are a big problem in residential areas. And unfortunately, farmers are an even bigger culprit in some areas when they spray fertilizer on their fields when the fields are partially frozen. In that case most of the nutrients runoff into the nearest stream. Crazy.

  4. i moved into the house i occupy 25 years ago, and shoveled out stones from around the shrubs that first summer.

    i still have the little white bastards turning up when i mow the lawn or turn over my wife's garden. they never go away.

    you'll never fully win.


  6. Yes. There is no easy solution. Add rubber mulch to this equation.
    Sorry , this is all I can say. i am still confused on what to use for mulch.
    My main objective to use mulch is to stop weeds growing in front of my house between the side walk and the foundation.
    The best solution is to pave the area with 12" x 12" stone or concrete square blocks over weed block fabric. When you want to remove them it is as easy as picking up the blocks. This may not be possible to do every where. Thanks for reading my suggestion.

  7. On rubber mulch/stones/cedar mulch. I have a small 9x3 south-facing flower bed in front of my townhouse in Atlanta GA (just had for a year). I had to paid a landscaper to dig down 2' to remove all the the dirt which was 70% rocks. (And I'm still finding rocks, you can't get rid of them.) Then replaced with dirt/compost/etc. For years I've used cedar mulch in previous homes, but just heard about the rubber so tried the rubber mulch. At first I loved it, I liked the dark color I chose, I could walk between the plants without dragging dirt and ants into my house. The plants loved it. But as soon as the Atlanta summer sun hit, I couldn't work near my plants, it would get too hot to touch it. It got hotter than the concrete driveway. Worse, leaves come down all year here, and you can't use the blower on it, the rubber pieces are too small and they all blow away, so it looked crappy all the time. Also, since the pieces are so small and lightweight, they work down into the soil, and are not decomposing as regular mulch does, so you are filling your bed with rubber. And you will have to top dress a lot. So I switched back to the cedar mulch, since it is the same color as dead leaves. If they made the rubber mulch in huge 6" pieces that wouldn't blow away with the blower, I would probably try painting them with high-heat rustoleum to see if they wouldn't get as hot, and top dress with that for looks, ok maybe not too much work. How about large mulch pieces made with the silicon they use for the new kitchen potholders? Or made from the material in the ove-glove? Just wishful thinking.

  8. I hate stone mulch. My thoughts: stones pack the dirt down, especially when they're laid 4" deep. They also keep the soil hot in dry spells and chilly in cold spells. I want more even temperatures which wood mulch. Actually, I buy mushroom compost for my beds. It looks nice and adds to the soil as soon as it's laid.