How To Test Your Garden Soil ? Gardening’s Great Mystery – Solved!

One of the greatest gardening mysteries for many gardeners is their soil type. Well, let me tell you, you just may have a variety of soils. I myself have three different types within our gardening acre – perfect loam, red clay and sand, all in that order. Glaciers sure did move things around in our lovely state of Wisconsin. And unscrupulous builders gave us the clay as ‘filler’ instead of the lovely black dirt we ordered. No matter, we can do two things with the soil we have:

  • Amend the soil for the type of plants we want
  • Select plants appropriate for the type of soil

Why do you have to worry about soil? If you garden, and you want a variety of plants, they usually want a variety of soil.

Simple, right? Let’s figure out what you have.

How To Test Your Garden Soil

Soil Structure

First, let’s chat about soil composition. The most common soil types are clay, silt and sand. Soil is made up of a variety of particles, and the combination of these particles makes up the soil density, which indicates the type of soil. Let’s take a look at our top three:


Clay, for example, is dense and packs tightly due to its composition of small, natural soil particles. Because of this density, little air can pierce clay and thus it will hold a lot of water and nutrients, but be slow in draining. As a result, any plants that need good drainage may end up with root rot due to the excessive moisture. On the plus side, moisture loving plants will rock in this soil!

However, if you wish to plant in this soil medium, then you will have to amend the soil. Combine some organic matter like mulched leaves, compost or composted manure to the soil prior to planting. Good to go!


Midway between sand and clay, silt also contains small soil particles. This soil, like clay, is less dense, but can compact easily; similarly holding in moisture and nutrients, it too can cause drainage issues. Amend the soil like clay, or aerate the soil by turning it over occasionally.


The opposite of clay and silt, sandy soil contains large particles of soil matter, and as a result its composition is loose. It has a lot of air pockets and drains very quickly. But don’t despair, many native and drought loving plants can thrive in sandy soil. Amending is still recommended, and that is accomplished by adding mulch or compost.


While not a specific soil type, loam is a combination of silt, clay, and sand. It is often considered to be the perfect soil, and most plants will grow very well in in it. In truth the PERFECT soil is the one that supports the plants you love.

Grandma’s Way of Determining Soil Types and pH Levels

Testing for Soil Types

While there are many ways to test soil, the old fashioned ways are usually good enough to support a beautiful garden. Here are a few tests that my grandma taught me. Each start with a handful of moist soil:

  • Squeeze it tight. Does it retain its shape without crumbling? Is it sticky? Good chance it is clay. Clay soil is sticky and retains a good amount of water.
  • Rub the soil between your fingers. Silty soil will feel slick and stick to your fingers.
  • Is the handful of moist soil crumbly and refuses to stick together? Then it is mostly sandy.
  • If it holds its shape, but crumbles when pressed with your thumb, you are lucky, you most certainly have loam.

The Acid (and Alkaline) Test

The soil types above can also be labeled as acidic or alkaline. These two make up what is called the soil’s pH level. Look around your yard; if you have pine trees, you more than likely have acidic soil, as evergreens grow best in that type. To determine the pH level with a bit more confidence, gardening suppliers have a plethora of testing equipment available. Or, if you wish to have the experts determine pH, take your soil samples to your local University’s extension, which provides farming and gardening resources and education to community members.

Testing pH Levels

Here’s how to test pH levels yourself:

Alkaline test – Take a handful-sized soil sample, from at least 4” down, and place into a waterproof container. Combine with a half cup of cider vinegar. Fizzing indicates higher alkalinity.

Acid test – Add a cup of water and about a tablespoon of baking soda to another soil sample. Frothing indicates higher acidity.

Easy, right? You can also measure the pH range with a purchased meter. Surprisingly, most plants enjoy a slightly neutral soil, which has a pH range of 6.5 to 7.0. Below 7, soil is acidic; above 7 it is more alkaline.

Amend pH Levels

If your plants require more acidity or alkaline, no fear, the soil is easy to amend:

Raise acid levels – combine sphagnum peat moss, sulfur, coffee grounds, or a high acid fertilizer. Mix well.

Raise alkaline levels – add lime or organic matter and mix well.

Remember that all the soil amendments you do may take a few months, or even the entire growing season to take effect. Each year of amending provides greater cumulative benefits, and every year thereafter, you’re gold!

Moisture and Nutrients


Another thing to ponder – is your soil dry, moist, or in-between? I’ll bet you have some of each. Super easy to check – moisture depends on the amount of rainfall and density of your soil. Dry or moist soils are also indicators as to which types of plants will grow in it. Ensure you check the plant labels to determine the required moisture levels.


Every garden benefits from the addition of compost. Composed of organic waste products such as yard waste, mulch and kitchen scraps, compost is easily applied with a gardening fork to the top layer of soil. For major benefits, apply compost at the beginning of each growing season. You can also add composted manure as a very beneficial, nutrient creating amendment.

Compost is an excellent way to amend soil. It improves air and moisture flow and helps bind looser soils together.

Sounds like a lot of time to test all this, but it really isn’t. If you did all your testing and observing at one time, using Grandma’s methods, it should take no more than a half hour.

What Types of Plants Work in What Soil?

The answer to this obviously depends on your test results, so if you have done the following tasks:

  • Test the soil type
  • Test the pH
  • Test the moisture

Then you are ready to purchase your plants and arrange them into a beautiful garden. Most nursery plants have labels that indicate in which type of soil the plants grow best. You will be pleased to find that many plants can survive in any type of soil!

Native plants generally love either moist, woodland loamy soil, or dry, gravelly, sandy soil. Grasses love a variety of soils, and brilliant flowers tend to like loam. Experience will eventually help you decide what plants thrive where, but in the meantime, offers a nice list of plants and their soil types.

In addition, Birds and Blooms offers:

Now, go test your soil!