Bags of Dirt
by Dan Clost
by Dan Clost


First serious garden earned 25 cents from the Kemptville Horticultural Society when I was 12. Have been poor in horticulture ever since but rich in spirit.

Went to work writing the Good Earth column (over 500 articles published in newspaper, magazine, website and journal.) and learned that what was printed wasn't what I wanted to say and certainly not what Gentle Reader understood me to say. Subsequently have developed a certain clarity and economy of words.

Day job- nursery and production manager for a large nursery/garden centre
Side job- Garden restoration and renovations, design consultations, remedial pruning.
Night job- garden writer and communicator (overnight success in another 20 years)

Dan gardens in Canadian Zone 5b

October 7, 2012

Dirt is under the refrigerator, soil is in the garden. Sort of doesn’t matter what you call it, Gentle Reader, you’re bringing it home by the bagful, lots of bagsful; and yes, more than three bags full.

Sometimes it is difficult to know what it is you’re bringing home in those colourful bags. Do you have triple mix, and if so what are the components? Is it gardening topsoil and how does that differ? Potting soil? Container mix? Seed starter? Black earth?

Should you make your own concoction using perlite, vermiculite, peaty moss, compost, sand, and last year’s leavings that are still in the pots? It would be helpful to have an idea before you get to the garden centre because when you’re standing there looking at a possible ten or more choices, the distinctions become blurred and it all becomes dirt.

Scott’s and Miracle-Gro products (the main player in the game) can be found in almost every outlet no matter what type of ownership the garden centre operates under. Two of the other main players seem to be Fafard (not such a giant but completely owned by Syngenta which is the giantest of all giants) and Premier Horticulture. A quick check of the box stores, as well as the independents, shows Scott’s and Miracle-Gro being the major product lines offered although Lowes has quite a range from many different producers although trying to track through all of the mergers and acquisitions over the past decade is quite the challenge. United Industries, Vigoro, is one such convolution.

If your intent is to start your plants from seeds or to grow them in long term containers, AgroMix® is a good option. Sphagnum peat moss, perlite, wetting agent, starter nutrients, composted manure, calcium enriched, perlite and vermiculite are in Agro Mix. It is available in 10l to 70l bags.

While The Pro Mix Bx® is similarly constituted with sphagnum peat moss, calcitic and dolomitic limestones and a wetting agent it also contains MycorisePRO®. The last ingredient is beneficial mycorrhizal inoculum, a fungus that colonizes the plant’s roots resulting in improved mineral uptake, water intake etc... (In itself, this is a topic that can easily take up several columns.) Use this product for transplanted seedlings into bedding trays, pots and hanging baskets.

Container mixes are formulated specifically for hanging baskets, balcony containers and large potted arrangements. Typically, the plants used in these selections are annuals purchased as bedding plants in May and then arranged into their summer homes for the duration. Some examples include Fafard’s Verandah Mix®, Fafard Organic Container Mix, Kellogg Premium Potting Soil, Miracle-Gro Organic Choice Potting Mix, and Miracle-Gro Potting Mix. Peat moss, compost, vermiculite and perlite are the 4 primary ingredients of most container mixes. From there, you can find different wetting agents (sphagnum moss being the most common) such as coir, fertiliser added in “starter” shots- usually in water soluble form or in long term such as 3 month slow release, different composts- bark fines, sea-enriched, and even manures- the list can be extensive. My suggestion, purchase the product with the clearest labeling that tells you exactly what is in the product. Some folks will tell you that proprietary information is a secret and we should be satisfied with vague terms. Not I, Gentle Reader. If it is a secret then it can remain their secret and their property; I won’t be bringing it home.

All things considered, the most important point about a container mix is that it is much, much lighter than garden soil. This means it won’t settle as much so that roots can grow easily through the medium and both water and air can move through the mix. Gardening Soil, and again all of the main players sell their own version of it, actually contains real soil. This is not meant for containers unless you considered raised beds to be such.

This product is used when planting perennials, shrubs, trees, and on lawns. Sometimes it is prudent to consider purchasing in bulk quantities of a cubic yard or more depending upon the job. The mixes vary somewhat in their soil content and may then be presented as a “specialty mix” such as a water gardening soil or rose soil.

Most have a loam base to which has been added manure or compost. There is a bit of kerfuffle going on about black earth at the moment. Detractors are saying it has zero nutritive value and they are correct. But…it is not supposed to. Its primary purpose (almost 100% decomposed organic matter making it stable) is a “conditioner” in the sense that it improves the tilth of the soil. The result is very similar to using a container mix in a flower pot, as mentioned in the above paragraph. And by the way, even though it does look pretty on top of the flowerbed, it is meant to be mixed into the soil. Mind you, I would rather use my own compost then pay for a product to do the same job.

I’ll stop there, Gentle Reader, for this week. Look for a column explaining commercial, municipal and home-made compost in the near future.

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