The best soil for runs has enough sand in it so it drains instead of holds water like clay. You do not have to add sand but adding sand will not turn it into concrete.
I added sand to our front yard flower bed because the clay was so hard to even dig in with a shovel thinking the sand would loosen it and improve it. It didn’t, it made it even worse.
So I added sand. Whoops.
Instant (unbaked) bricks. Not literally concrete, of course, but no bueno.
I have enjoyed reading comments on the issue of adding sand to clay soil. I live on a lake, and most of my soil is sand. Plants will sprout fast, but they just don't grow well after that. I have lots of good drainage, just nothing in the sand to promote sustained growth.
I have already mentioned that the best run setup for me was dumping all my organics (grass clippings, leaves, wood chips, etc...) into the run. The chickens will level out the litter in the run. I think you could set up a chicken run composting system on a slope. The organics have great drainage, and you can let it compost in place and later use it in your gardens.
Anyways, I found some good information on the issue of adding sand to clay online which may be helpful...
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Mixing sand with heavy clay can backfire if done improperly. It’s one of those gardening myths that seems logical but often leads to frustration (and concrete-like soil).
Why Clay + Sand Can Become Rock Hard
Clay particles are
microscopic and plate-shaped, while sand particles are
much larger and rounder. When you mix a
small amount of sand into clay, the clay fills in the gaps between sand grains, creating a dense, compact matrix that:
- Reduces drainage
- Increases compaction
- Hardens like concrete when dry
This is especially true if you use
builder’s sand or sharp sand, which has angular grains that lock together tightly.
When Sand Can Help Clay
To improve clay soil with sand, you need to go big:
- At least 50% sand by volume—a massive amount
- Incorporated deeply, not just surface-mixed
- Combined with organic matter like compost or leaf mold to buffer the texture
Without that scale and balance, you’re better off skipping sand entirely.
Better Alternatives for Clay Soil
Instead of sand, try:
- Compost: Improves structure and feeds microbes
- Leaf mold or shredded bark: Adds porosity and organic bulk
- Gypsum: Helps break up clay chemically without altering pH
- Cover crops: Deep-rooted plants like daikon radish can aerate clay naturally
If you’re working on a rural repair or soil stabilization project (say, around a post or tool handle), the clay-sand mix might be useful for
intentional hardening. But for gardening or root health, it’s usually a trap.
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I hope some of that information was helpful. It makes sense to me. But like I said, I have sandy soil and hardly any clay where I live.
) is a great amendment to any soil, whether heavy clay, mostly sand, or anywhere in between. The best soils to grow things are generally a good mix of clay, sand, and organic material (compost). The clay contains certain minerals that the plants need. The sand helps with drainage. Compost helps with the tilth of clay soils, moisture retention of sandy soils, and provides certain nutrients (like nitrogen) that leach out of the soil over time.
