A good quality potting soil is a very important part in a plants healthy growth, especially when growing plants in containers.You can put a healthy plant in poor soil and it will not grow very well. You may be wondering why you just can't dig soil out of the garden and place it in a container. Potting soil is different then garden soil, and growing in a container is different then growing in a garden. Garden soil is not airy as it compacts down, creating poor drainage. In the garden, good soil works well as the moisture goes down so that the plants roots are not sitting in water for a long period of time. There are several factors that make up a high quality potting soil. A high quality potting soil has good drainage, which is important to a plants health. A plants roots need air. If the soil remains too wet around the plants roots there is no air and the roots will rot, which in turn will kill the plant. Drainage is important but you also want the soil to be able to retain moisture too. If plants don't get enough moisture they will dry up and die. Good potting soil, should be sterile. The last thing you want to do is introduce insects, fungus, disease or weeds to the plants in your container. A soil less potting soil will not have any soil borne problems. A good potting soil will be neutral with a pH of 7.0. If the pH is too low the soil is acidic. Some plants prefer a slightly acidic soil such as rhododendrons, azaleas and strawberries, but generally plants do best in a soil with a pH of 6.5 -7.
A good quality potting soil consists of a certain percentage of sphagnum peat moss, compost/humus, perlite and/or vermiculite. What the potting soil is being used for will determine the percentages of what goes into the potting soil. Indoor soils used for indoor plants are lighter weight then those potting soils used for outdoor containers. Potting soils for outdoor containers will have more compost/manure added to it.
Sphagnum peat moss adds nutrients to the soil, increases the soil acidity and holds water. Compost/humus is decomposed organic matter. It can be composted leaves, shredded bark, manure, etc and adds nutrients to the soil. Perlite and vermiculite are lightweight volcanic rock, filled with air. Perlite is used in place of sand or grit. It adds air pockets to the soil by separating the fibre and opening up the soil, which helps with drainage. Vermiculite opens up the soil and is able to hold nutrients as well as water so that the soil does not dry out as quickly.
Be careful when choosing the right potting soil, as they are all not created equally. There are cheaper potting soils available but they might not be balanced or contain good quality compost. Many times you are better to pay a little more money to purchase a good quality potting soil because in the long run, the plants will be healthier. I like to compare it to building a house. You would not build a house on a poor foundation and expect it to stand up and the same thing goes for potting soil. The soil is a plants foundation. A good quality potting soil is one of the first steps in growing strong healthy plants.
