Planting soil is soil that has been specially prepared for planting. It contains the nutrients necessary for plants to thrive, and its pH balance has been adjusted to be suitable to the types of plants which will be grown in it. It is possible to purchase planting soil from garden supply stores, and also to prepare your own.
There are a number of sources for planting soil. People with poor soil or contaminated soil may choose to bring in a load of planting soil from an external source, removing the top layer of bad soil and replacing it with the planting soil. This can be a good idea when starting a garden from scratch, to ensure that plants have healthy soil to thrive in. The fresh soil also reduces the risk of disease, by removing soil which may have been contaminated by plant pests and diseases.
Typically, planting soil is amended with compost and mulch to create a very rich, crumby soil which is highly suitable for growing plants. Additional minerals may be added to meet the needs of specific plants, and the pH is often neutral, unless it has been modified. Gardeners can sometimes order a specific planting soil mix for their garden, using the guidelines for the plants or crops they are growing to determine the correct blend of minerals and pH. It is also possible to use a neutral soil and make amendments to specific areas of the garden.
Gardeners can also work the existing soil in their garden to turn it into planting soil, in a practice known as soil preparation. When gardeners work the soil, they use gardening tools to turn the soil and break it up while blending in compost, mulch, and other materials to enrich the soil and make it better for growing plants. Many people work the soil every year when they grow crops, typically after the last harvest so that the soil has a chance to rest after it has been amended for the following year's crops. Soil preparation is also critical when establishing an ornamental garden, as plants will fail to thrive in poor or inappropriate soil.
Potting soil is a specific type of planting soil which is formulated for plants in pots. Potted plants have some specific needs which need to be addressed, such as good drainage and an ample source of minerals. Many potting soils are also fertilized so that potted plants will grow quickly. As a general rule, potting soil is not suitable for use as generic planting soil in the garden.