Potting soil is a mixture of substances used as a planting medium for container gardening. A majority of potting soil is produced commercially, and it is suppoesd to mimic optimal growing conditions found in real soil on the ground. What type of potting soil to use will depend on the needs of your plants. Potting soil can also be made at home to cut costs.
Potting Soil Basics
Potting soil is a mixture of several elements used for container gardening or for topsoil purposes. While the term suggests it actually contains soil, most potting soil mixtures are soil-less. Instead, potting soil contains ingredients that are much lighter that soil and offer appropriate nutrient balance for the plants. Most potting soils contain a mixture of peat moss, sand, perlite, composted bark and recycled mushrooms. Different types of potting soils will have specific mixtures of each ingredient for the unique needs of the plants using the soil.
Commercial Potting Soil
The main benefits to using commercially bought potting soil are that it will save you time and that it has been sterilized, lowering the chances of plant disease transmission. A majority of commercially sold potting soils do not contain any actual soil. While less common, soil-based potting soil is available for purchase. You'll see many different kinds of potting soil marketed, but it is best to first be educated on the needs of your plants. For example, succulent and cactus plants need well-drained soil, so choose a type of soil that has close to equal parts of organic matter, such as composted bark, and sandy matter, such as sand or perlite. If you are planting from seed, ensure the mixture has some peat moss, which helps make the soil more fertile for your new plants' growth. All-purpose types of potting soils are usually suitable for plants that need a lot of acid, such as blueberries (Vaccinium spp.).
Homemade Potting Soil
Depending on how much potting soil you use, making it at home could save you some money, especially if you have a lot of garden waste compost lying around. Homemade potting soil is made by baking the compost with water for a short amount of time. It is usually necessary to add fertilizers to homemade potting soil.
Even with a well-balanced potting soil, you may still have to supplement the soil in your containers periodically to improve the health of your plants. Adding compost to the pots will help. Also, replanting the plants into bigger pots and adding more compost can help plants that are struggling. Watering the plants with a compost or manure tea once or twice a month can also help keep the plants healthy. If it is a drainage issue, ensure the bottom of your pots have a 1-inch layer of stones to assist in the drainage process.