A plant is no better than what it grows in. Got good dirt…er, potting soil?
Had a dream the other night, vivid enough to wake me to text myself a morning reminder; however, the next morning I this message on my phone: pit t soi imdian mods. Took a while to figure out that it was a reminder that, decades ago while working in the MSU horticulture greenhouses, we used soil partly excavated from ancient Indian mounds.
I remember questioning the archeological and cultural implications of destroying ancient relics just to grow throwaway poinsettias. The answer I got was “Yeah, we use it because it is easy to dig.” But not to worry, it turned out to be from piles of rubble left over after researchers had carefully sifted through small earthen piles that contained mostly mussel shells, broken pottery, animal bones, and the like.
But very few gardeners use actual dirt in potting soil anymore, because it packs down and gets hard. Besides, modern soilless mixes do quite well. Trouble is, it doesn’t take long to figure out that, with store-bought potting soils, you get what you pay for. Some use mostly cheap bark or chipped wood, which dry out quickly.
The very best store-bought potting soils have some finely-ground bark for bulk, long-lasting peat moss to hold moisture and nutrients, and a little perlite (white, crunchy stuff made by heating and “popping” volcanic ash) or grit to keep the potting soil loose and aerated as the other ingredients decompose.
By the way, I know that England’s garden guru Monty Don and other garden writers are lock-step against peat moss, but it’s because European peat has been totally used up; however, here in North America we have millions of acres of peat fields, more than can ever be used, and the harvested peatlands quickly revert to their natural state. Being an independent international peat moss inspector, I can get into detail, but the bottom line is that peat moss is abundant here and its use is not destroying the environment. And transportation costs aside, it is a lot less disruptive to the environment than coconut coir. Really.
Anyway, I and a lot of gardeners just make our own blends, and though there are as many recipes for potting soil as there are gardeners, we mostly use the same basic ingredients of bark, peat moss, and perlite (very few ever use sand or vermiculite). My basic mix, which I store in trash cans, is cheap and works well for all kinds of plants, is three parts bark, two parts peat moss, and one part perlite. If I need more bulk, I use more bark; for better moisture-holding capacity I add more peat moss; and for better drainage I add more perlite or grit.
Keep in mind that all potting soils, being mostly organic matter, gradually break down and lose their functions, so it’s important to repot plants every now and then. To feed my plants I often strew a handful of compost, which provides a richness that commercial fertilizers lack, but once a year I use a half-strength dose of slow-release beads plus an occasional shot of liquid fertilizer.
Lastly, whether indoors or out, I always mulch my potted plants to help reduce water wicking in the sun or low humidity indoors, and to foil harmless but annoying little gnats feeding on decaying organic debris. I water twice times, a few minutes apart, to really soak it in, then leave it until plants get nearly dry.
My potted plants seem happy, leaving me to just dream about digging dirt from the past.
Felder Rushing is a Mississippi author, columnist, and host of the “Gestalt Gardener” on MPB Think Radio. Email gardening questions to rushingfelder@yahoo.com.
