How to Separate Soil from Rocks [7+ Fast & Easy Ways]
Soil and stones shouldn’t mix as this can damage your lawn mower or other automatic gardening tools. No worries, there are many ways to separate soil from stones and pebbles.
Rocks and stones can be separated from soil by (1) hand-picking, (2) winnowing, (3) sieving or sifting, (4) rock-raking, (5) using a soil-blocking cloth or screen, (6) using big machine attachments, (7) using a vacuum, a snowplow, a nut gatherer, a power broom, or a rototiller.
However, remember that stones can prevent root rot, help drain water and aerate soil. They can hold sun heat overnight and keep root vegetables (radish, peanut, ginger, carrot, garlic, onion) toasty. Hence, having them in a soil where you grow plants can be pretty useful. But that’s not all. Read on, there’s more to the story.
Why Separate Soil and Stones?
Some plants thrive on pebbly, rocky, or gravelly soil but most plants can’t get enough of the nutrients they need. In addition, stones can damage power tools, stub toes, or fingers. Also, planting in rocky soil can be challenging.
However, rocks in the garden can be of help. For instance, if you’re in a wildfire area, rocks are fireproof. Gravel can help prevent soil erosion. Stones can also help keep weeds away. And if you’re into rockeries or cactus, they’re perfect. Moreover, rocks (small in size) can help to improve the drainage of heavy soil especially if planting water-sensitive plants such as rosemary and lavender.
In addition to that, if you’ve stepped on a sharp pebble or stubbed your finger or toe on a rock, you know that it’s best to remove them from the soil, as you don’t want to repeat that pain.
At the same time, it’s easier to plant in soil without stones. Also, garden tools and soil implements can be damaged by pebbles, rocks, stones, or gravel in the soil.
FACTOID: Stones, rocks, and pebbles that are separated from the soil can be used for borders, pathways, rockeries, and so on.
To remove soil or dirt from rocks or gravel, power-washing with water is the answer. However, to separate stones from potting soil or garden soil, use your hands, or any of the many time-saving, energy-saving tools available. Here’s a summary of what’s available.
1. Hand-picking: Use Your Fingers
Removing stones by hand from a pot of soil is one of the easiest, most immediate ways to separate soil from stones. It is important to wear protective gloves.
Indoor gardeners often arrange a layer of stones at the bottom of a pot before adding soil. This serves two purposes: it adds weight so that the pot is more stable and doesn’t easily tip over.
More importantly, the stones also allow airspace where roots can breathe, as well as provide space for excess water to drain away from the soil and out through the pot’s drainage holes.
This layer of stones is also great for keeping the soil away from the drainage holes, where they can compact and clog up the holes. This is when poor drainage happens and plants can die from root rot.
To keep the soil separate from the stones, cut a piece of cloth, fold, and lay over the layer of stones before adding soil.
FACTOID: When kids are out of school for the summer in rural American farmlands, they can earn a minimum wage by picking rocks from fields to prevent damage to crops and equipment.
2. Winnowing: Use Wind and Gravity
Winnowing is a way of separating light and heavy components by using gravity and wind or blowing air. This method is used to separate the husk from grain or seeds or stones from the soil.
Where there is wind or a strong breeze, winnowing is a method that allows the rocks or pebbles to fall while the soil falls a bit further away. To winnow a few small pots of soil, the rocky soil can be lifted about one meter high (or more) by hand.
To winnow larger amounts of soil, a container can be used to lift the soil. In either case, let the soil fall slowly and from a high enough distance to allow the wind enough time to blow the soil away as the rocks or pebbles fall down.
In either case, it is best to winnow rocky soil that is loose. In other words, break apart clumps of the soil before you start winnowing.
3. Sieving or Sifting: Using a Mesh or Screen
Rolling pebbly soil on a mesh screen stapled to a long wooden frame – or shaking stony dirt in a holey plastic fruit crate – either way, gravity works to separate soil from stones or gravel.
Sifting and sieving are similar, so people can use them interchangeably to mean separating the parts of a mixture, such as pebbles and soil, for example. However, one requires shaking while the other lets gravity do the work. Let me explain.
First of all, the tool you need to use in this procedure is anything with a lot of holes. This can be anything from a flour sifter (smallest holes for tiny pieces of gravel) to a plastic fruit box (bigger holes for bigger stones). Check out a dirt sifter such as this one on Amazon.
For clarity, I use the word “sifting” to mean that you shake the tool vigorously from side to side, such as when you are sifting flour or sugar to remove lumps. This is fine if you’re working on a pot or two of soil (hand-picking or winnowing will work for that).
When using a mesh or screen without shaking it, I use the word “sieving” to mean that it’s gravity that does the work.
Here’s how to sieve rocks from the soil with less effort.
- You’ll need a long screen frame, about 8 feet long by 2 feet wide, (2.5 m by 60 cm). You can make such a sieve with chicken wire (or hardware cloth) and a wood frame.
- One end of the sieve should be much higher. When you shovel soil at the higher end, you want the soil to go through the sieve while the rocks, stones, or pebbles roll down to the lower end.
- Don’t enclose the frame at the lower end, so that the stones can roll out and away. If you do, you’ll have to lift the frame to dump out the stones.
- For better roll-down, increase the height for a steeper angle.
- If some oddly shaped stones stin in the sieve holes, pick them out between shovelfuls.
4. Rock-raking: Dig In and Pull
A rock rake, also called a landscaping rake, gravel rake, or rock windrower, are made of heavy, durable metal. The tines can dig in and pull out rocks or stones from topsoil.
The tines of a landscape rake are long enough to penetrate about 2 inches (or more) below the soil surface. For deeper surface penetration, choose a rake head that’s made of durable, heavy metal.
The rake should be able to pull up roots, stones and other debris to the surface, but the soil should stay in place because there is sufficient space between the tines of the rake.
You can do this in three simple steps.
Step 1: Loosen the Soil: To remove small rocks from your yard, farm, or garden, begin by using a rototiller to loosen the soil, break up the dirt, and turn up stones, rocks, and pebbles.
Step 2: Rake and Pile: After rototilling the soil, use a heavy-duty garden rake, beach rake, or rock rake to pull away stones, rocks, or pebbles from the soil and pile them up.
Step 3: Gather and Transport: Gather the piled pebbles, stones, or rocks into piles or into a wheelbarrow.
PRO TIP: When selecting a rake for the best removal of rocks or stones in the soil, choose a heavy metal garden rake (not a leaf rake), with a head that is typically more than 13 inches wide such as a handheld rock rake like this one.
A durable landscaping rake is a good investment because it can do different jobs such as spreading mulch, level soil, prepare land for planting, make gravel paths, remove gravel, and so on.
A landscaping rake that is designed to be attached to a small tractor or wheeled vehicle (yes, even a golf cart) will make your job faster and easier.
5. Separate Soil: Landscape Fabric or Geotextile
To prevent soil from clogging the drainage holes in pots, lay a piece of cloth or coffee filter over a layer of pebbles before adding the soil. The same principle goes for yards, gardens, and landscaping lawns where a landscaping fabric separates soil and stones.
To separate soil from gravel or pebbles in potted plants or indoor gardens, many use plastic mesh or coffee filters. However, in landscaping, the soil-blocking cloth is used for wider areas.
Also known as landscape fabric (here is an example of how it looks like on Amazon), or geotextile fabric, these materials allow water to pass through but soil, dirt, and debris stay put. Materials vary from non-woven (closed fabric or thin plastic) to open mesh and warp-knitted fabric or cloth material.
FACTOID: Geotextiles are used in landscaping, engineering, road construction, drainage control while home gardeners use landscape fabric to keep the shape of garden beds, to prevent soil erosion, or to slow down weed invasion.
6. Use Attachments
When removing large pieces of rocks or clearing large plots of land, the most efficient way is to use machines. From simple machines such as rakes and pry bars to bigger machines such as garden tractors, the bigger machines can best reduce time and effort.
For those with small backyards or gardens, you can start by loosening the soil with a garden fork, a shovel, or a rototiller. As mentioned, a garden fork or a pry bar can be used to loosen heavy rocks that are embedded in the soil. Then, gather the rocks, stones, and gravel by using a large gardening rake.
If you have a lot of smaller stones or gravel, you can use a soil sieve or a sturdy screen to sift the soil. If you don’t want to go through attaching a metal screen or chicken wire to a wooden frame, you can use a plastic fruit crate with small holes all over. Fill the crate with pebbly soil, hold the crate handles, and shake.
However, if there are big rocks or a high number of stones all over a wide area, you will need more manpower or you can use bigger tools or machines. If you have a garden tractor with different attachments such as large gardening rakes, blades for grading the soil, and heavy-duty plows, you can use these.
Check out an electric, cordless rototiller such as this one on Amazon.
After piling up all the rocks, pebbles, and stones, use a wheelbarrow to move them away, or to where they can be put to better use.
7. Four Bonus Tips (with Video Examples)
Three creative suggestions for separating stones from soil include the use of a nut gatherer, a vacuum cleaner, a snowplow, and a power broom or a rototiller. Videos show exactly how to use these.
Use a Nut Gatherer: A nut gatherer can be used to pick up pebbles, small rocks, or stones from soil. It’s so easy to use: all you have to do is hold the handle and roll it over the ground surface. This way, it can help avoid pain in the elbows, waist, and knees. However, arms and elbows will get a workout. Also, this method needs a lot of time and patience to clear a large area. Check out a rolling nut gatherer such as this one on Amazon.
Use a Vacuum Cleaner: Separating the lawn from the gravel driveway is easy, even when the gravel gets on the grass. You’ll need a long extension cord. Also, you won’t be able to remove rocks that are bigger than the vacuum hose. However, a vacuum cleaner is faster than raking or picking up gravel by hand.
Use a Snow Plow: Separate pebbles, rocks, or stones from the soil quickly and easily by using a snow plow to turn up buried stones. Since you’re driving the snowplow around from a seated position, it’s not as backbreaking or laborious as the other methods suggested here.
Use a Power Broom or rototiller: After a winter of plowing snow, some gravel can move from the driveway and get onto the grass. Many have tried using a power broom or a rototiller to keep the yard free of gravel, pebbles, rocks, or stones.
Why do rocks come up to the surface of the soil? If you recall, water freezes when it expands. When there’s water under a stone or a rock in the soil, the expanding water pushes the rock upwards, little by little. Imagine how the repeated freezing, expanding, and push can eventually bring the rock to the surface of the soil.
How do I keep dirt away from the pretty pebbles around my potted plant? Lay some coffee filters between the pebbles and the potting soil.
Can rocks or stones affect the health of my potted plants? Yes, some minerals in rocks or stones can change the pH level of the soil. This, in turn, can affect the health of your plants.
Do indoor plants need stones in the soil? No, not really. However, if the plant is heavier than the pot, rocks can keep the pot upright instead of tipping over. However, in this case, the best thing to do is repot to a larger container.
And that’s it. You’ve just reviewed some of the best ways to separate soil from gravel, pebbles, stones, or rocks.
Why it’s necessary: While a few pebbles or stones adds minerals to potting soil as well as helps aerate the soil and drain away excess water, too many can deprive your plants of the nutrients that they need to thrive. Stones, gravel, and rocks are best removed from crop fields, lawns, and garden soil to prevent accidents and avoid damage to tools and machines.
What you can do: For a few pots of soil, pick out, sift, winnow, or rake away the stones by hand. To keep the stones, wash away the dirt with water pressure. For landscapes, driveways, pathways or gardens, use a soil-blocking cloth to separate soil and gravel. For bigger fields, use a tractor with a plow and screen. In addition, you can also use a vacuum cleaner, a snow plow, a rolling nut-gatherer, a power broom, or a rototiller.
Congratulations! You’ve just completed a thorough review of the why and how of separating soil and stones. Happy gardening!
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- “A Summer Ritual: Rock Picking in the Midwest” by R. Lowry in Time Magazine
- Garden Hits & Myths: Can rocks really aid soil drainage?” by H. Hole in Edmonton Journal