A common question when it comes to container planting, is why even use potting mix instead of plain ol’ garden soil?
We can tell you that it’s like comparing apples with oranges! Garden soil definitely belongs in the ground, whereas potting mix should only be used for pots. If you use the wrong material for the job then it may have a less than desirable effect in your pots and garden.
Firstly we need to understand how potting mix is different to soil.
Potting mix is a mixture that you add to pots when planting your plants. Each is different, but as a general guide it is comprised mainly of peat, composted bark, sand, perlite, and compost. Some also contain fertilisers and wetting agent. Potting mix does not contain any soil at all. The purpose of potting mix is to hold the plant in place, hold water for the plant’s roots to soak up, and provide nutrients to feed the plant. It is very well drained, as well as light in weight.
To put it simply, soil is the natural loose surface material consisting of inorganic particles and organic matter that covers most of the land surface. Soil provides the structural support and the source of water and nutrients for plants. Every soil is a mix of gravel, coarse/fine sand, silt, clay, and organic matter.
The reason you don’t use soil in potting mix is that garden soil tends to be heavy and without tilling, either by you, earthworms or other insects, it begins to compact after several waterings. This compaction will damage plant roots and not allow water to penetrate though (causing drowning and disease). The other reason is, disease spores, bacteria, plant eating insects, weed seeds and assorted other nasties can easily hitch a ride with your garden soil. Potting mix is sterile in a bag.
Make sure you use the correct material in your garden for best results – soil in the ground, and potting mix in your pots. Use a premium potting mix in your pots for even better results.