Crimson clover is an effective cover crop to protect and improve soils as well as promote beneficial insects.


By Tom Karwin,

We have seen a surge of interest, recently, in soil regeneration as a substantial part of the global response to climate change.

Briefly, soil regeneration (or carbon farming) involves practices that reduce the loss of carbon from the soil and draw atmospheric carbon into the soil. These practices can counteract the disruption of nature’s carbon cycle caused by modern practices such as burning fossil fuels and pursuing “conventional” methods of commercial agriculture and livestock operations.

The greatest positive effects of carbon farming are realized when these practices are applied to hundreds of acres, but home gardeners also can combat climate change by carbon farming on their own patch of land.

Adopting these enlightened practices entitles the gardener to claim the status of Citizen of the Earth. But wait — there’s more. Carbon farming also improves the overall health of the garden, increases the retention of moisture, reduces workloads and avoids the costs of garden chemicals.

The basic idea is to support the vitality of the top few inches of the soil, where most of a plant’s roots find nutrition for the plant and where we have the microbiome, the vast population of beneficial bacteria and fungi that is essential to healthy plants.

As we learn about the importance of the soil microbiome and its fragility, we understand the damage that is done to it by churning the soil, exposing it to harsh sunlight and wind, and dosing it with herbicides, insecticides and synthetic fertilizers.

The first steps in carbon farming at home, therefore, include no tilling, no synthetic chemicals and no bare soil.

• Keeping the soil covered means filling the garden with perennial plants and filling in the gaps with annuals or organic mulch. Between vegetable crops, or when redesigning a garden bed, plant cover crop plants like clover, to be mowed or turned under before setting seed.

• Generally, leave roots in the ground to decompose. After harvesting vegetables, cut the top growth and leave the roots. Mow, cut back or heavily mulch weeds instead of pulling them.

• When planting the garden, emphasize biodiversity, including deep-rooted grasses and nitrogen-fixing species.

• Compost yard waste and kitchen scraps.

Naturally healthy soil needs no chemical treatment to minimize pests and diseases, or to keep plants growing. (Scientists advocate remineralization of the soil by adding rock dust. I’m learning about that idea and will write about it in a future column.)

As consumers, buy food that has been grown with regenerative and organic practices. Find such items at farmers markets and stores that carry organic foods. (All organic foods are non-GMO; foods that are labeled “natural” could be anything.)

As voters and policymakers, advocate against factory animal operations and for well-managed pasture-based livestock operations. Rule out synthetic fertilizers and pesticides on athletic fields and public lands. Support the management of public parks and other properties with practices based on organic methods, integrated pest management and soil regeneration.

Change might be difficult for some, but building healthy soil is definitely worth the effort!

Here’s a timely opportunity to add California native plants in your own soil regeneration project: The Monterey chapter of the California Native Plant Society will have its annual plant sale from 10 a.m. to 1 p.m. Saturday, Oct. 3, at MEarth, at Carmel Middle School, 4380 Carmel Valley Road.

Tom Karwin is president of the Friends of the UC Santa Cruz Arboretum and a Lifetime UC Master Gardener. Visit for more information, and send comments or questions to

Tom Karwin

Tom Karwin writes about gardening. He is a UC Master Gardener and vice president of the Friends of the UC Santa Cruz Arboretum. He gardens in Santa Cruz. Visit his website at Reach the author at .

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  • "Keeping the soil covered means filling the garden with perennial plants and filling in the gaps with annuals or organic mulch."

    Not sure how the focus fell on perennial over annual. That's not what this guy is saying at all. Most if not all of us have gardens full of perennials (fruit trees etc) and gaps filled with annuals (vege's, flowers etc).

    There were many more important points that struck me as common sense:

    plant cover crop plants

    no tilling, no synthetic chemicals and no bare soil.

    Naturally healthy soil needs no chemical treatment to minimize pests and diseases

    support the vitality of the top few inches of the soil,

    leave roots in the ground to decompose

    cut back or heavily mulch weeds instead of pulling them.

    Compost yard waste and kitchen scraps

    emphasize biodiversity

    • And that's where you, Rob, Dave and I all agree 10000%. If you look at our yards, we all use the same common sense principles. Oh yeah, we each focus on something in particular, but the overall approach is the same (and I think what the author was getting at?).

  • Does it tick all the boxes?

    The first steps in carbon farming at home, therefore, include no tilling, no synthetic chemicals and no bare soil.

    • Keeping the soil covered means filling the garden with perennial plants...

    I absolutely disagree.

    I'd think 'the first steps in carbon farming at home' would be to grow stuff...and since you'd grow stuff to eat, most of it is surely going to be of the  annual persuasion. Now if Karwin et al want to argue that you cannot carbon farm so well with annuals then we're all our billions.

    We'd starve.

    But that's not true.

    The fantasists are even trying to create perennial grains -- but don't hold your breath. Current farming practices suggest that annuals can fulfil a lot of carbon farming attributes especially if the crops are partnered and the roots left in situ...and the soil not disturbed aggressively.

    I think the research on holistic grazing techniques suggest that the mix and match approach -- engineered for each locale's ecology -- is a very efficient carbon farming technique.Indeed when we look at the waxing and waning of carbon sequestration communities in ecology it is not as simple as perennial plants (such as among forests) equal the best carbon draw down.

    The sea sequesters carbon.Australia's sparse Central Desert  botany has at times out performed the five star rain forests on the planet. Even massive carbon sequesters like the forests of British Columbia are much more complex than just perennial trees. They are absolutely animal dependent in way of salmon and bear in order to survive and thrive.

    When push comes to shove are you seriously going to say that you won't garden unless you can grow a certain percentile of perennials? If that is so what plants would they be? And Permaculture design aside, how are you gonna mix the long lived stuff with the annuals and feed yourself day in and day out ?

    Switch your menu to fruits and nuts and pass on the starches and greens?

    Even if you lay down perennials for the long haul --in your wee urban back yard -- what assurances have you that  your 'soil regeneration' program is guaranteed of success? And if it was or wasn't how would you harness that quality? With bigger and more trees and shrubs? If you muck up the mix you are stuck with a forest outback with limited sunshine which will limit  the variety of other plants you can grow exponentially  as the perennials grow bigger and more dominant each year.

    I'm sorry but as far as I can see -- aside for a few selective well chosen  plants -- 'perennial gardening' is an urban sham IF you want to grow most of the stuff you can eat.

    It becomes a shibboleth.

    It's not about 'filling in the gaps' at all...and I'be very surprised if many folk here follow that formula of 'gap filling'.

    Then there is the complication that grasslands are among the largest ecosystems in the world ; their area is estimated at 52.5 million square kilometres, or 40.5 percent of the terrestrial area excluding Greenland and Antarctica .

    And grasslands, in the main, are driven by annuals...

    • Dave, I cannot see your point here, neither the article nor anyone's response to this post to date have indicated that you cannot garden if you do no have perennials. ... its just a suggestion to use them. 

      Here are 3 legumes for people who are looking for perennials that are not trees (there's lots more little perennials, I'm just leguming it :)  

      Lucerne, red clover and white clover.

      I have not tried red or white clover, however I am keeping lucerne until it disappoints me ... so far it's done quite the opposite, due to it's many uses above and beyond a deep rooted nitrogen fixing perennial.

      My take on this article is, if you can, if you want, if you've got a space, try a perennial (I did not get the impression that they were suggesting to add giant trees to your veggie patch) ... I'm sure that California have some small natives ...

      I'm interested in the use of the multi-use type small perennials that produce food, fodder or green mulch. In doing this I am hoping to give some more permanent residence to the hard working microscopic guys (including EM) in and around my annuals in the veggie patch.

      I am spacing a few larger (functional) trees around the veggie patches for shade (This was inspired by yourself Dave, when you pointed out the obvious about shade and using trees for our Qld summer).

      And I remind myself that at the end of the day, if the large plant/shrub or tree's not working ... chop and replant something completely different.

      • I'll believe you when you cut down a Davidson Plum, Rob!  LOL. 

      • I read the article and thought of Geoff Lawton's food forests.  I have quite a few perennials but I would never think of eliminating annuals.  I don't think he meant that at all. 

        I firmly believe in no tilling, no chemicals and no bare soil.  Between perennials, annuals and compost/mulch, I don't think there is a gardener in the world who would disagree with that nowadays.  He is even including annuals that are weeds like clover.  

        "...'perennial gardening' is an urban sham IF you want to grow most of the stuff you can eat."  At the risk of being Frank (I'd like to meet Frank one day... he must be dead ugly).... bollox!  My lettuce do far better under the paw paw and perennials like that than I could ever do without them.  I eat a lot of greens and they need summer shade.  I'd rather use some kind of tree than build a shade structure and waste all those resources.  

        It's like anything I guess.... balance is the key. 

  • This article makes good sense, and we can easily adjust our gardening practices to suit.  

    My latest read is a book from the 1940's era, by Maye Bruce and her attempts to find ways of improving soils and QR compost (quick return). 

    • A great old lady! Read the book as a download. There's been an update by Andrew Davenport, he's on BLF although may not follow us now. His website has a lot of info on Maye Bruce and subsequent events.

      There's doubt about whether we could import the compost starter but there's plenty of other compost starters available without hauling stuff in from overseas. Earlier batches will do just as well.

    • Reminds me of my Esther Dean book, No Dig Gardening, from way back.

      • Had the privilege of meeting her at an event at Q Uni some years back. We have all of her books. She was still actively gardening at 90-something but may be pushing up daisies by now.

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