May 2006
Soil Basics By Bob Steinkamp

When customers stroll down the potting soil aisle in your garden center, do you often notice confused looks on their faces? This confusion may be brought on by the wide array of soil products that are available. Peat moss, top soil, peat humus, container mix, planting mix, lawn soil, manure products, mushroom compost, garden soil and potting soil are just a sampling of the soil products available today.

How is the home gardener supposed to select the right product from this myriad of choices? How will your customers know they are spending their money on the appropriate products for their specific gardening needs? With a little knowledge, you and your employees can help clear up this confusion for your customers.

Knowing all of the nuance and differences of all of these products makes selecting the right product much easier. The first thing you need to know is soil products can be grouped into three basic usage categories: potting soils, container mixes and soil amendments. All of these products come in a variety of compositions and price points.

Potting Soils

While widely used, the term “potting soil” is a misnomer. Very few, if any, potting soils contain actual soil. Instead, these potting mixes are made with combinations of organic and inorganic materials such as peat moss, bark, compost, perlite and similar materials.

Some potting mixes are designed for use with specific plants, such as orchid mix, African violet mix, cactus and succulent mix, and water garden mixes. Some mixes can be used to help seed germination. If the mix is not labeled for a specific plant, it is for general use.

General-use potting mixes are suited to a variety of plants and container sizes. They can be used to root cuttings and germinate many types of seed. Many times, general-use mixes are used for re-potting plants into larger-sized pots. Foliage plants, flowering plants, herbs and vegetable plants can all be grown in a general-use mix.

Some of these potting mixes contain enough fertilizer to last for several months. If so, this information will be clearly marked on the bag. If not, the plants will need to be fertilized soon after potting. All the gardener needs to do is follow the directions shown on the back of the bag.

Container Mix

Container gardening continues to grow in popularity among home gardeners. Consumers are growing vegetables, herbs, flowers, foliage plants and even small trees and shrubs in container gardens. Special potting soils called “container mixes” are available for this application.

Most container mixes include a slow-release fertilizer that will last up to three months. Some mixes contain a water-holding gel. These gels act as a reservoir by absorbing and holding water. This allows for a longer interval between waterings. The presence of the fertilizer and gel will be clearly marked on the bag.

Soil Amendments

Many gardeners strive to improve their existing soils. Clay soils can be poorly drained and hard to work with while sandy soils can dry out too quickly. Almost every soil can benefit from the addition of a soil conditioner.

Soil conditioners are rich in organic matter. When mixed with clay soil, this organic matter breaks up the clay, improving drainage and ease of tilling. With sandy soils, the organic matter helps improve water retention, allowing longer intervals between waterings. Soil amendments are usually mixed into the top 6-8 inches of the garden or can be used to help repair dead spots in the lawn. Peat moss, topsoil, peat humus, garden soil, lawn soil, manure products and mushroom compost are appropriate for this use. With the exception of manure products and mushroom compost, soil conditioners do not have much fertility value. Their purpose is to improve the texture of the soil.

When planting trees and shrubs, gardeners can improve their soils by mixing soil amendments with the back fill. The hole is dug, the plant placed and the hole re-filled with a mixture of soil and soil amendment (follow directions on the bag). Any of the above-mentioned products could be used. Specialty products called “planting mixes” are also available for this use. Planting mixes usually contain some fertilizer and are pH adjusted.

Your garden center has a lot of different products to offer customers. Knowing the differences among the products in your potting soil aisle will help you stock the right products and assist your customers. So, no matter if your customers are re-potting houseplants, improving flower gardens, planting shrubs or starting container gardens, you should know what the correct soil product is for that purpose.

Bob Steinkamp

Bob Steinkamp is Florida technical services manager at Conrad Fafard, Inc. He can be reached at [email protected].