By Dennis Patton

Soil is the foundation of all gardening. Growing healthy plants starts with good soil for healthy root development.

If we can grow vigorous roots the rest of the plant will take care of itself. We tend to focus on top growth and not root development. All soils are not created equal. They have different components. Our success depends on making sure we have the right components for proper growth.

Soil is not dirt. Soil is what we grow plants in. Dirt is what collects on the furniture or under your nails. Soil is simply a mixture of sand, silt and clay particles combined with organic matter. Water, air and oxygen are the other main components. Gardeners have taken the term soil beyond the basics and have engineered various mixes to achieve greater success. This is where we need to get down and dirty to fully understand soils.

Topsoil

Topsoil is the natural layer that forms on the earth’s surface that developed over millions of years from rock decomposition, wind and water movement.

Our Kansas City area topsoil is high in clay . Heavy clay soil, while nutritious, doesn’t always have the ideal properties for growing healthy plants. It can hold excess moisture during rainy periods, or be brick hard during droughts, affecting root development. For practical purposes, topsoil is what you already have in your yard. It works but may not always have the most desirable properties.

Enriched Topsoil

Since our local clay soils may not be the best quality for growing plants, there’s enriched topsoil. This is a mix of local topsoil and organic matter. Remember, it’s the organic matter that improves the quality of our soils for better growth.

Here is the important point; if you are filling a low spot, use topsoil. Purchased topsoil may not be better quality than what’s already there. But if you want to grow plants, go with the enriched topsoil. It’ s superior to topsoil as the organic matter improves how the sand, silt and clay bond.

Potting (Soilless) Mix

Potting mix is used in container gardening. The best quality potting soils do not contain soil (dirt). They are called soil because we grow plants in the material. Potting or soilless mix is a mixture of peat moss, pine bark and organic materials. They are specifically blended to have the right blend of air and water-holding pores to promote proper growth.

Adding topsoil or enriched topsoil to a container creates a dense mix that often lacks proper drainage because of the clay. The formulated particle balance of a soilless blend is ideal when used in small volumes as it provides the best environment for optimal root development.

Unfortunately, these mixes tend to be more expensive than topsoil. Potting mix or soil comes in bags at the garden center right alongside the less costly topsoil or enriched topsoil. Remember your intended purpose when purchasing soil.

If filling a hole, not concerned about plant growth, use topsoil.

If you are improving your existing topsoil or building a garden planting bed, purchase enriched topsoil or compost to incorporate into the topsoil. When creating a container garden then use soilless potting soil or mix.

Now that you have the dirt on soil, it puts you on the path to success, helps to avoid costly mistakes and leads to happy and healthy plants.

Dennis Patton is horticulture agent at the Johnson County K-State Research and Extension Office.