Almost any article on plants ends with “and make sure you use a good potting mix” – great advice, but what does it mean? Let’s go over some of the basics and see if we can answer that question. To know what a good potting mix is you kind of need to know what the purpose of a potting mix is, so let’s discuss that first. The main functions of a potting mix are:

To hold moisture and nutrients around your plants roots, acting as a reservoir for these critical elements of life in your container garden.To provide enough air for growing roots to be able to breath and not rot once you plant your container. Most people don’t think about this, but it is critical to have a good amount of air in the soil.  Not enough and usually the plant roots have a hard time surviving.To support your plant, providing anchorage for the roots. A soil mix needs to settle around the roots of your plant and help hold it in place, so that it doesn’t blow over from the first wind.  However, it also needs to be light enough to allow water and air to always be present under the soil surface so your plant’s roots have a balanced atmosphere to grow in.

So given that a good potting mix does these things, any number of different materials can be used.  I know many gardeners use soil from their garden in their pots, some make their own compost and add this to their containers. You can do any of these things, but if you are making your own potting soil at home you will also need to change the way you water and fertilize in order to get the best results. From hydroponics to sewer sludge, there are a million ways to mix up a potting soil, however, the potting soil you buy at most garden centers is a simpler blend of some basic items.

ules of Thumb For Choosing a Potting Soil:

Potting soil used in containers should be light and fluffy.
Look for a potting soil made up of peat moss, pine bark and perlite or vermiculite.

Fertilizer may be added in the form of a “starter charge” or slow release formulation. 

Adjust your fertilization practices accordingly

Potting soil may use moisture retaining treatments, watering patterns may need to be altered if you use a potting soil containing these substances.