When I first became interested in a wide variety of indoor plants, I prepared soil mixtures with the care and precision I had used in making the formulas for our children. It involved trips to the woods for leaf mold, sifting and mixing ingredients, and sterilizing the ordinary soil which we used in order to kill the seeds that are found in almost all soils. In our Long Island home we had an extra stove in the basement which we used for canning and other secondary purposes. I’d fill the oven with old baking pans and other receptacles which contained my potting soil, and light the burner. Frankly, it “reeked” and the reek was all over the house. It was as though we were burning feathers in the fireplace. Now that I am less energetic, and somewhat wiser, I buy prepared soil.
I find that for a reasonable number of plants the prepared soil is not costly and saves a lot of time and preparation. Of course, if you are a professional you may have your own ideas about soil, and your own formulas for a mixture. I’ll admit I do a little mixing on my own, but that is because I grow many different kinds of plants in pots, and each has individual preferences. Most cacti and succulents need something sandy that doesn’t hold moisture too long, as is natural in their desert homes. Tropical plants need a light, porous medium that is rich in moisture-holding humus, like decayed leaves on the jungle floor. Some plants get nourishment only from acid soil, some need alkaline soil, some like soil nearly neutral. I’ve found Michigan peat moss a good starting base regardless of requirements of individual plants.
I like to dish it right out of the bag. When done, I always pull the plastic inner liner together to keep it moist. In extra dry weather I often wet a sponge and put it on top of the mixture. Potting is a pleasure, because Michigan peat feels so soft, silky, and clean. At repotting time I discover well-developed, healthy root systems.
For plants that require better-than-average drainage—mostly succulents—I mix peat moss with builders’ sand. (Want to know where I got my last batch of builders’ sand?—from a contractor who was building a house down the road. He and his wife happen to be begonia lovers and he was charmed to know about my book All About Begonias.) The formula for the mixture is two-thirds soil and one-third sand. For even greater aeration, I may throw in a moderate ration of crushed charcoal.
On the other hand, some of my plants insist that their soil always be moist. For them I add coarse vermiculite, perlite, or Pelonex, and in a similar ratio. These soil conditioners have the ability to hold moisture without making the soil muddy or soggy.
There is another item on my potting-soil shelf—a jar of horticultural lime. This is for plants that dislike acidity. I either add it to the potting soil—a scant teaspoon per three-inch pot—or mix it with water, to be applied later. With or without these added ingredients, I feel that a good potting soil has sufficient nutrients for almost any plant for several months; so I seldom mix in fertilizer of any kind.
Potting
When and how to repot a plant should be the least of a gardener’s problems. Here is a case where hovering, pampering, and fussing usually does more harm than good. Plants are often better repotted mañana than today.
I know many of my plants have benefited from the fact that I have been too busy to repot them whenever the impulse came over me. I hate to think how many I have killed with kindness in my less active years.
Remember my Aunt Minnie? She embarked on a big repotting spree every spring, but not very often in between. Some of her most handsome specimens have lived in coffee tins and large juice cans for years. Instinctively she knows when a plant should be repotted. Don’t ask me how she knows it. And when that time comes, she goes about it in a firm, no-nonsense manner, firmly but tenderly.