Garden Myth Busted! Don’t Add Sand to Clay

October 16, 2009 | By | Comments (8)

Clay soil curses most gardeners in the South. It drains poorly, dries hard as a rock, and restricts the movement of air, water, and plant roots. It’s a pain in the butt to garden in. So naturally, we look for things we can add to it to loosen it up and save our aching backsides.


A lot of people think you can loosen up clay by mixing in lots of sand. It’s sounds logical. After all, among all the constituents of soil, clay particles are smallest and compact the most, while sand particles are biggest and compact the least. Adding lots of sand will therefore break up that clay, right?

Wrong, wrong, wrong, rototiller-breath! Sand mixed with our Southern clays forms a sort of nasty concrete. When it dries, just try digging in it. You can jump from a tree onto the shovel blade, but the blade won’t move and you’ll lose your dentures.

Instead of adding sand, add organic matter — lots of it. Any kind will do — sphagnum peat moss, garden compost, composted cow manure, grass clippings, chopped up leaves, chopped pine bark, potting soil, worm castings, whatever. Organic matter coats the clay particles, opening up pores in the soil through which air, water, and roots can freely move. It also makes the soil comfy for earthworms and other organisms that loosen the soil even more.

So forget sand. Add organic matter to your soil every year, in gross quantities if you can. Organic matter can turn even the worst clay soil into good soil within a couple of years.

The Grump hath spoken!  


Photo by Jared.


  1. Steve Bender

    I see no point in adding a layer of sand atop a layer of organic matter in your raised bed. I would just add a 50-50 mixture of topsoil and organic matter.

    August 27, 2012 at 1:10 pm
  2. Dona

    what if you are adding sand to a say one foot 6″ raised bed that is above clay? will the sand fall through the organic matter eventually and make concrete around the deeper reaching root? or does it stay suspended? it is a permanant bed that will not be tilled.

    August 27, 2012 at 12:22 pm
  3. Grumpy Gardener (His Benevolence)

    I think the best way to improve clay soil is by adding lots of organic matter — like, for instance, Canadian sphagnum peat.

    April 30, 2011 at 8:16 am
  4. canadian sphagnum peat

    I have tried mixing clay and sand. And I found out, that still, the clay was very sticky. There was no good result when we mix clay and sand. I don’t have any idea on what to do with clay. What I’m using now is pure loam It is very effective.

    April 26, 2011 at 7:59 pm
  5. Grumpy Gardener (aka His Excellency)

    Good advice, Emmit. You guys up north certainly know your….uh….manure.

    November 28, 2009 at 10:36 pm
  6. Emmit up north

    You said it! Clay plus sand is the recipe for adobe, so if you want to grow a garden on a brick, add sand to your clay. Here’s a quick test to try on your clay soil. take a bit of damp or wet clay between your fingers. If it feels gritty, then it already has all of the sand it needs, you need to add humus. If it feels silky smooth, then it would probably benefit with some sand, But!! First raise the humus level. If this is a new garden, with nothing planted yet, you might try an old technique called “green Manure” plant a quick growing annual crop like rye or soy very thickly. then when the plants are only about a foot high, rototill them under. repeat this as often as needed to produce a humus rich topsoil. And don’t forget the old fashion Brown manure, the kind that comes from cows and horses, It’s till a good source of humus. Whatever you do, it’s always easier to improve the soil in a new garden when you don’t have to contend with working around old plants.

    November 24, 2009 at 6:33 pm
  7. Grumpy Gardener (aka His Excellency)

    Don’t argue with Daddy!

    November 4, 2009 at 5:32 pm
  8. carolyngail

    And spoken well, Grumpy! My daddy knew that from farming on Alabama clay. Three words : Cotton burr compost. It breaks up clay better than just about everything and Daddy would always plow it back into the soil.

    November 4, 2009 at 8:49 am

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