Mulch is useful, but we’re better off growing living mulch- a mixture of plants growing a permanent ground cover, producing mulch right where you need it.

Here’s why.

  1. Mulch is expensive, doesn’t last long, and spreading it is hard, dusty work!
  2. Living mulch provides twice the protection – it produces a thick ground cover of living plants AND mulch from the dead leaves and stems. You double your protection against weeds and water loss from soil through evaporation.
  3. Living mulch creates twice the habitat – a mini-ecosystem of plants and flowers for birds and insects PLUS mulch for beetles, earthworms, and other detritivores.
  4. Fire protection – Living mulch is generally less fire-prone than dry mulch and even more so when we use fire-retardant plants.[1]

But did you also know that living mulch is better at delivering food to our soil ecosystem and increasing organic matter and carbon levels in our soil?

Living Mulch provides ‘Silver Service Catering’

Growing living mulch, we increase the amount, diversity, and consistency of food supplied to our willing teams of nutrient recyclers and soil structural engineers (see diagram below). Provided with a decent diet, these microbes and other soil organisms work 24/7 recycling plant nutrients and making them available to plants when they are needed.[2]

Diagram showing the value of living mulch for our soil

“Plants get ‘Silver Service’ catering directly from our soil ecosystem, rather than intermittent, and inadequate inputs supplied by us.” Wendy Seabrook

Living mulch also supplies additional organic material from roots and root exudates to our soil ecosystem. Root exudates are the sugars and proteins plants release from their roots to feed fungi and bacteria in our soil.  Plants allocate 20-60% of the solar energy they capture to produce these exudates.

When scientists first discovered root exudates, they thought the plants had something wrong with them and called the phenomenon ‘Leaky Root Syndrome’. But plants know what they are doing! Growing in functioning soil ecosystems, plants get 85 to 90% of the nutrients they need via the exchange of sugars for nutrients with microbes, and there are many other benefits.

Living Mulch increases Organic Matter and Carbon Levels in our Soil

We used to think that above-ground inputs of organic materials like mulch, crop stubble, and compost increased organic matter and carbon retention in our soil. But it’s not true. These above-ground sources of organic materials have a limited effect on carbon and, therefore, the organic matter levels in our soil.[3]

Most of the carbon is released back into the atmosphere with each ‘out-breath’ of the soil organisms feeding on the plant remains![4] That’s why mulch has the annoying habit of disappearing so quickly!

Only living plants have the technology to provide the roots and root exudates needed to increase organic matter and carbon levels, and thereby soil structure, water, and nutrient storage.[5] [6]

Getting Practical

Next time you’re working hard spreading dead plant material, think instead about growing living mulch and discover the fail-safe techniques in our publication – Living Mulch – Tired of Mulching? Grow Mulch right where you need it

Front cover of the learning from Nature publication - Living Mulch

References – Grow Mulch right where you need it!

[1] Mark Chladil and Jennifer Sheridan, 2006, Fire retardant garden plants for the urban fringe and rural areas (https://www.fire.tas.gov.au/publications/1709 Brochure.pdf). Tasmanian Fire Research Fund.

[2] Wendy Seabrook, 2019, Eco-logical Farming Handbook. Publ Learning from Nature

[3] Daniel P. Rasse, C. R. &. M.-F. D., 2005. Is soil carbon mostly root carbon? Mechanisms for a specific stabilisation. Plant and Soil 269, 341–356. (https://link.springer.com/article/10.1007%2Fs11104-004-0907-y)

[4] Michael W. I. Schmidt, Margaret S., et al., 2011, Persistence of soil organic matter as an ecosystem property, Nature 478 (https://www.nature.com/articles/nature10386)

[5] Daniel P. Rasse, Cornelia Rumpel & Marie-France Dignac, 2005, Plant and Soil (2005) 269: pp 341–356 (https://link.springer.com/article/10.1007%2Fs11104-004-0907-y)

[6] Michael W. I. Schmidt, Margaret S., et al., 2011, Persistence of soil organic matter as an ecosystem property, Nature 478 (https://www.nature.com/articles/nature10386)

Feature image by Simon Berger

    8 replies to "Grow Mulch right where you need it!"

    • John Brisbin

      Terrific article Wendy. I feel like there’s so much conceptual depth packed into these short paras that I will need to chase up the reference materials to get a better understanding. The ideas you’ve presented here can be discussed and re-presented many more times, I believe. Just wrestling with the Christine Jones quote is going to take me the rest of the evening!
      Thanks as always for a nourishing snack from the garden knowledge bar!

      • Wendy Seabrook

        Thanks, John. Soils are interesting and complex, but mulch versus living mulch is certainly worth thinking about. And something I would like to follow through with more information later…

    • Chrissy Woltjen

      Hi Wendy, Thanks for all the great information in your posts. I enjoy reading them. Now, what I was wondering about, is the organic matter in the soil not important and how else then mulching can we add this amount? Would green manure a better solution even so it is mainly used to get the accumulated nitrogen into the soil. Well, there are still roots attached, but suppose, they have to be working to leak out. You make me think!
      Love Chrissy

      • Wendy Seabrook

        Hi, Chrissy!
        Thanks for your nice feedback! In answer to your questions, I think mulch and composts etc are great tools to kick-start the build-up of organic matter soils, but living mulch is a tool we can use to help us continue to add organic matter without the hard yakka of mulching year in year out. Living mulch is a tool to make our food growing systems more self-maintaining and we can include legumes in our species mix to increase nitrogen levels in our soils. Green manure is great for veggies, that may not grow well in living mulch (see previous post on living mulch). But it’s not a permanent cover and is generally cut and worked into the top layer of soil before planting.

    • Eric van Beurden

      Fascinating stuff thanks Wendy. When we bought our place there were lots of bare eroded patches on the steep slope down from the house where you could see that runoff was washing away the topsoil. As an emergency measure we cardboarded them over and topped it with ti tree mulch. The established ground covers are now slowly invading these areas and we are also cutting holes in the cardboarded areas to plant fruit trees. However its terribly dry and degraded under the cardboard because, while it does stop the water erosion during heavy rain, it also prevents that same rain from entering the soil at all and the only carbon going in is from the cardboard when it rots down…which is very slow! So I am taking your advice now and even letting the established Singapore Daisy remain as a carbon factory that is clearly quite happy in this soil. Where to draw the line between wanted and weeded? That is now a much fuzzier line in my mind.

      • Wendy Seabrook

        Hi Eric
        Glad you enjoyed the post.
        I agree with your comment – where to draw the line between wanted and weeded – in relation to Singapore Daisy.

        The Permaculturist Geoff Lawton comments “that it is great in a food forest as living mulch, trees love to grow out of it”. However, in my State in Australia – Queensland, the Singapore Daisy (Sphagneticola trilobata) is a restricted invasive plant under the Biosecurity Act 2014.

        Knowing your site and that it’s not going to expand its range, it does seem to be a useful initial living mulch species able to survive on your compacted and eroded soils. Like some other ‘weed’ species the Singapore Daisy is acting as a pioneer species, helping you to repair your land. It would be great if you can start adding some other living mulch species into the sward. Legumes and biomass accumulators in particular. I’ll have more information on how to establish these in the Living Mulch Toolkit.

    • Kate Ward

      Hi Wendy,
      We have heard, at a biochar conference actually, that Mychorizal fungi won’t exist apart from a live plants, no matter what claims are made. So we were keen to plant into living green manure this spring. We are trying Okinawin Sweeet Potato, and planted this straight into Woolly Pod Vetch. The Woolly Pod Vetch has thus far proved itself to be my favourite winter legume for my situation. The vetch however was, and still is, quite vigorous so I did put mulch on top of it to slow it down. So I have actually ended up doing both dead and live mulch. I did save a bit of time and effort in the planting by not trimming or ploughing anything though. I used a new lithium battery powered cultivator to dig little planting pits into the vetch. Worked well. Yes the plantings are doing super well, so are some other things I didn’t plant… The wallabies are stoked I have planted more sweet potato, they think it is so delicious. Much better than that other aromatic stuff I grow. I have therefore put fleece over the crop, held down with home-made sand bags to keep them off the merchandise (they haven’t quite worked out they can just pick up the fleece with their little hands if they want to). This also has acted like a nice little nursery. So now the sweet potatoes, along with some weeds are busting out of their fleece. Altogether these plants have had a good start to life I reckon.
      Now the question is; should I be pulling up unwanted competitor plants, or is cutting them at their base the way to go, or should I just leave em if they aren’t a big deal??
      Also do worms prefer dead carbon from mulch or carbon from root exudates? Is it good to have a variety of worm types, say composting and earth worms to cover all bases?? What do ya reckon?

      Cheerio for now,
      thanks for your brain space, Kate Ward, from Broadwater.

      • Wendy Seabrook

        Hi Kate – lovely to hear from you again! To answer to your question – should I be pulling up unwanted competitor plants, or is cutting them at their base the way to go, or should I just leave em if they aren’t a big deal?? I think it’s important to look at what those plants are doing. We know that having a diversity of plants helps diversify soil food webs, and they are providing biomass and root exudates for your soil organisms. If you do cut them – leaving the roots is the way to go if they won’t reshoot.
        Re root exudates – it’s mainly food for bacteria and fungi rather than earthworms.
        Enjoy your growing – Wendy

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