Garden Soil Explained, What Soil Do you have?

When it comes to gardening, soil is a crucial factor that needs to be considered and understood. In fact, it is one of the most important resources on the planet as 95% of our food comes from soil.

What is Garden Soil?

Soil is the loose surface material covering the planet that contains a mixture of decaying organic matter called humus, minerals, living organisms, air, water, and tiny bits of broken rock. Although this is the simplest definition, soil is much more complicated than this. Soil contains the 17 essential nutrients required for plant growth, and in combination with air and water, plants absorb these nutrients through their roots. Additionally, millions of organisms can be found in a tablespoon of soil, including fungi and bacteria.

Soil Layers

Soil usually has three layers, the topsoil, subsoil, and bedrock (parent material). The topsoil contains more humus, air, water, and nutrients, making it the most fertile layer. The subsoil is denser, has less air, and is less nutritious. The type of soil depends on the location as the topography and climate play a role in creating the soil over time.

What Makes Good Garden Soil?

The amount of sand, silt, and clay present in soil determines its quality. Each of these three elements has different particle sizes and, therefore, different surface areas. Clay-based soil holds nutrients and water effectively, while sandy soil doesn’t hold nutrients and water but retains more air.

The ideal soil should contain:

  • 25% water
  • 25% air
  • 5% organic material
  • 45% minerals
Soil Triangle Diagram

If your soil isn’t that great, there are several ways to improve it, including using fertilizers to increase soil nutrients, adding compost to increase organic material, draining waterlogged soil, or adding lime to make acidic soils more alkaline. However, if your soil is mostly composed of rocks and gravel, it may be unsuitable for growing plants due to the fact that it will have less ability to hold water and nutrients. In such cases, it may be best to build raised beds and bring in quality topsoil.

Different Types of Soil

There are six main types of soil: sandy, silty, clay, peaty, chalky, and loamy. Each has its own unique characteristics and suitability for plant growth. Understanding your soil type can help you choose the right plants for your garden and make informed decisions about soil management.

1. Loamy Soil: The Ideal Soil for Gardening and Growing Vegetables

Loamy soil is considered the ideal type of soil for gardening and growing vegetables. It is a mixture of 20% clay, 40% sand, and 40% silt, avoiding the extremes of clay and sandy soils. This type of soil combines the strengths of the other two types, as it doesn’t dry out during the summer heat or become waterlogged in winter. Loamy soil is dark, crumbly, fertile, well-drained, and easy to work with. It has a texture that supports most types of plants.

USDA, Loamy Soil seen here feels crumbly and is usually darker due to the fact that it contains more organic matter. NRCS CC BY-SA – 4.0

2 – Sandy Soil

Sandy soil is characterized by having over 68% sand particles and very little clay. It is also known as light soil because it drains quickly after rainfall or watering. This type of soil is generally low in plant nutrients as they tend to wash away after rain. Additionally, sandy soil is often very acidic.

However, sandy soil does have some advantages. It warms up quickly in the spring, which allows for earlier planting.

sandy soil
Sandy Soil can be see here, usually low in fertility and poor moisture retention properties. USDA, NRCS CC BY-SA – 4.0

3. Clay Soil

Clay soil is categorized as heavy soil and typically consists of at least 30% fine clay particles. This type of soil is compact and poorly drained, but it is nutrient-rich. During summer, clay soil hardens like rock, and during winter, it becomes waterlogged. The addition of organic matter can enhance drainage and aeration in clay soil.

clay soil
Clay soil usually goes hard when dry and sticky when wet. Soil Science, NC State CC BY – 2.0

4- Silt Soil

Silt soil is composed mostly of silt particles, making up around 80% of the soil. This type of soil can be easily compacted due to the fineness of its particles. When left exposed, silt soils are susceptible to wind erosion. Fortunately, silt soils are not commonly found in garden environments. Adding organic matter and gravel can help improve silt soil. Silt soils have a slightly soapy and slippery texture and don’t clump together easily.

5. Peaty Soil

Peaty soil is characterized by its high levels of organic matter and acidic nature. It is typically found in swampy marshes and bogs and is easy to work with. Peat soil forms through the gradual decomposition of aquatic and semi-aquatic plants, which accumulate in layers over time.

6- Chalky Soil

Chalky soil is highly alkaline, which can be a big challenge for gardeners as some plants struggle to grow in this type of soil. The high alkalinity makes it difficult for plants to access essential nutrients, with a pH level around 7.5 or higher. This means that important nutrients like manganese and iron are not readily available to plants.


Do you know what type of soil you have?

One way to find out is by conducting a basic at home soil test. To determine if you have chalky soil, simply place a handful of soil in a jar of vinegar. If the soil froths, it contains calcium carbonate or limestone, indicating that it is lime-rich.

Simple Soil Test – Click on Image to Enlarge

Another important factor to consider is your soil’s pH level, as it can affect which plants can grow and how you manage your soil. The pH scale ranges from 0 to 14, with 7.0 being neutral. A pH level below 7.0 is acidic, while a level above 7.0 is alkaline.

The pH level of your soil can impact plant growth, as some plants prefer a higher or lower pH. It’s recommended to test your soil’s pH level before designing a new garden or moving into a new home. It’s also wise to get a commercial test done to test for any soil contaminants or heavy metals that may be present in the soil when you move into a new property.