How to Tell What Type of Soil You Have (and Why It Matters)
If your plants are struggling—wilting, drying out too quickly, or just not thriving—the problem might not be your watering or your seeds. It might be your soil type.
Different soils behave in very different ways. Sandy soil drains fast but doesn’t hold nutrients. Clay soil holds water like a sponge, sometimes drowning your plants. Silt is fertile but can compact and suffocate roots. And loam? That’s the gardener’s dream—a balanced blend of all three.
So how do you figure out what kind of soil you actually have? There’s a simple test you can do at home with nothing more than a jar, some water, and your own garden soil. It’s called the Jar Test—and it can tell you a lot about how your soil works and how to improve it.
The Jar Test: Step-by-Step
Here’s how to run the test yourself:
What You’ll Need:
A clear glass jar (like a mason jar) with a lid
Soil from your garden (enough to fill 1/3 of the jar)
Water
A teaspoon of dish soap
A marker or masking tape
Steps:
Collect your soil. Scoop soil from about 6 inches deep in your garden bed. Try to remove sticks, roots, and rocks.
Fill the jar. Place soil until the jar is about half full.
Add water. Fill the rest of the jar with water, leaving a little room at the top.
Add dish soap. A small squirt helps break up soil clumps so particles separate more clearly.
Shake! Put on the lid and shake vigorously for at least three full minutes.
Set it down. Place the jar somewhere it won’t be disturbed.
Now, watch what happens:
After 1 minute: Sand particles will have settled at the bottom (they’re the heaviest).
After 30 minutes: Silt will form the next layer above the sand.
After 24 hours: Clay finally settles at the top, making up the last layer.
Use your marker to draw lines at each layer as they appear. That’s your soil profile!
Reading Your Soil Profile
When your soil has fully settled, you’ll see distinct layers of sand, silt, and clay. Measure each layer, then calculate the percentage of each compared to the total depth.
Example:
Sand: 50%
Silt: 30%
Clay: 20%
That mix tells you what type of soil you’re working with.
The Soil Texture Triangle (Loam Chart)
Soil scientists use something called the Soil Texture Triangle to define soil types based on percentages of sand, silt, and clay.
Loam—the “gold standard” of gardening soil—usually contains about 40% sand, 40% silt, and 20% clay. This balance creates soil that:
Drains well (thanks to the sand)
Holds nutrients and moisture (thanks to the silt and clay)
Provides a soft, workable texture for roots
Soil Texture Triangle or Loam Chart
Here’s a quick guide:
Sandy Soil: >70% sand. Drains fast, low fertility.
Clay Soil: >40% clay. Poor drainage, sticky when wet, cracks when dry.
Silty Soil: >70% silt. Fertile but compacts easily.
Loam: A balanced mix that’s ideal for most plants.
How to Improve Your Soil
The good news? No matter what your jar test reveals, you can improve your soil over time.
If you have sandy soil: Add organic matter like compost, worm castings, or biochar. This improves water-holding capacity and nutrient retention.
If you have clay soil: Add compost and mulch to improve drainage and structure. Planting cover crops also helps break up compaction.
If you have silty soil: Protect it with mulch and cover crops to prevent erosion and compaction.
If you already have loam: Lucky you! Maintain it with regular additions of compost and mulch.
Remember—soil is living. With the right care, it can be built and improved year after year.
Final Thoughts
The jar test is a simple but powerful way to understand your soil. Once you know your soil type, you can make smarter choices about watering, fertilizing, and amending. Healthy soil means healthier plants, bigger harvests, and a thriving garden.
So grab a jar, give it a shake, and see what secrets your soil is hiding. And if you want to supercharge your soil building, don’t forget—worm castings are one of the best organic amendments you can add. (That’s exactly what we make at Sunnyside Soil!)
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