I run across very few people who can tell the difference between soil and potting media. To make matters worse, companies that sell soil products are not always forthright on the labeling.
The dictionary definition of soil is, “The upper layer of earth in which plants grow, a material typically consisting of a mixture of organic remains, clay, and rock particles.”
How many of you feel this is what you got when you bought your last bag of soil at a garden center?
On a recent outing to a local home improvement box store, I decided to check out their soil inventory. I saw two products with a label stating top soil and garden soil across the bag.
I was suspect almost immediately of the claim on the bag. I looked for a busted bag in each stack so I could look at the material up close. Once I found a bag ripped open, my suspicions were well-founded: Not even close to being soil or even resembling true soil in its natural state.
Both bags had very similar mixtures consisting of wood chips, clumps of clay and a small amount of some type of organic material. In my experience, these types of bagged soil products do more harm in the garden than good.
First, having big chunks of visible wood in the mixture tells me that my soil pH will lower during the continual decomposition of the wood. Also, most of the wood chunks will float to the top of your beds with a few hard rains, defeating the purpose of the soil mixture.
Next, the clumps of clay will only slow down your soil respiration and affect your plants’ health. The only thing going for these bagged mixtures is the compost. With that said, each bag was composed of less than 25 percent compost. You see, wood chips are cheap filler, and so is clay.
The only real expense the companies have in making this subpar soil mixture is the compost, which is why not much is added to each bag. These bagged soils are a total ripoff, and I encourage you to stop buying them. If you want real topsoil, go to your local feed store or plant nursery and ask them for bulk topsoil.
Potting soils, like Miracle-Gro, ProMix, Sunshine Mix, etc., are really not soil at all. Instead, they are mostly composed of peat and perlite, with some containing slow-release fertilizer. In my line of work, we call this type of media a soilless mix.
These products are intended to be used in flower pots, hydroponic systems, seed germination, small flower beds and indoor growing. Soilless mixtures are great at keeping plants from drying out too fast in pots. Plus, they provide a loose substrate for young roots to grow through.
Most potting mixes are not good at holding nutrients over a long period time. Some companies add slow-release fertilizers to the mix. This is also why houseplants require a little more fertilizer than soil-grown plants. Soilless mixtures were really never meant to be used in outdoor raised beds, like many of us do. Your plants will grow outside in them, but nowhere near what they would in true loamy garden soil.
In summary here, never buy bagged topsoil or garden soil. Only use potting soil in flower pots and indoor gardens. Last, if you want real soil for your garden beds, go to a local nursery and ask to have topsoil mixed with mushroom compost. You can have them load up your pickup truck or they will deliver it for a small fee.
If you have already filled your beds up with a peat-based media, don’t worry. You can always add real soil into your beds and start improving your garden’s soil health.