Last time, we deeply meditated upon the truth about potting soil: types, pros and cons. If you haven’t read that installment, take a moment now to review soil-based and soil-less potting mixes.
Now we come to one of my favorite topics, making your soil mix. Why do I enjoy making my own? I guess I get to return to my childhood (some would say I never left), when I mixed a bit of this and that from around the yard in my sandbox to make some imaginary concoction. There is a certain satisfaction when you discover your recipe in which beautiful plants flourish.
Why mix your own versus just buying a bag from the garden center? Well, because it is fun (see previous paragraph), can be less expensive in certain instances and is, perhaps, more environmentally friendly to boot. One quick story to illustrate, shall we? One summer I managed a small production nursery for a start-up, budget-strapped public garden. I had a large number of young trees needing transference to larger pots, and I had zero potting soil. What I did have, however, was a large pile of well decomposed pine nuggets, field soil and sand. Oh, and a cement mixer. My only real option was to use the ingredients I had on hand in some mixed ratio, a ratio yielding me the best of the characteristics described in my last post. We fired up the mixer and started experimenting until we were satisfied with the result. We utilized local resources to create a potting media for little cost.
There are many different recipes out there on the internet for soilless soil mixes, so I shall leave off on the topic. The biggest drawback to DIY soil-based mix is soil sterility. YouTube is full of different homemade attempts to sterilize soil. I shall leave it to you to discover one for yourself. One way to begin the process is to stack sod, allowing it to break down over a six months period to obtain a quality “garden soil.” However you chose to begin, a basic recipe might be one part garden soil, one part screened (actively turned) compost, and one part sand (see the above links for specs for sand). Mix in a clean environment, such as upon a clean tarp or wheelbarrow, being sure to thoroughly mix for a uniform, consistent product.
If you do not want to create your own mix, you can always modify one you purchase. This is especially necessary when you want to modify a commercial produced media for growing specialized plant material such as alpines or orchids.
Now that I have really mixed things up, we shall chat next time about the various potting soils Wellfield uses, and we will also share some lessons learned.
Josh Steffen, Horticulture and Facilities Manager