About a year ago a plastic bag containing a grayish powder arrived at my home. The accompanying note said that if I added some to the potting mix of my choice or to just plain peat moss, I might be intrigued by the results. I did and I was. By adding the material to some milled sphagnum peat moss (in the recommended 1-cup-to-1-quart ratio), I made up a planting mix for some African violets that had remained far too long in their original starter cups. These stunted little plants responded to their larger quarters and the new growing medium with very rapid growth. They overtook some other violets that had been in larger pots for some time, and most of them went on to bloom prolifically.
Later I heard that Rex Gregor of Plymouth, Minn., had had a similar experience on a much larger scale. Mr. Gregor, a sales representative with Prentice-Hall Publishers, has done market gardening (tomatoes, peppers, cabbage, and broccoli) and run a small commercial greenhouse part time for the better part of 40 years. His principal greenhouse product is hanging baskets of impatiens, cascade petunias, and double wax begonias, among others. He concedes that his experiments with the product don't meet strin gent scientific standards for testing. Even so, his observations are telling.
Mr. Gregor added the product to his regular potting mix for half of the plants in his greenhouse and fed the other half with a commercial fertilizer as usual. Within four weeks, he says, ``you could walk into the greenhouse and tell snap dab, on the button, which side had the treated soil mix and which hadn't.'' He found a similar impressive difference among his tomato, pepper, and other seedlings.
A couple of years ago Judd Ringer, whose Ringer Corporation in Eden Prairie, Minn., produces a line of biologically active fertilizers, and his chief biologist, Don Loveness, took a look at the many soilless potting mixes available and concluded that manufacturers had strayed too far from the natural way in producing them. In most natural situations plants grow in a mix of organic matter and mineral materials. The soilless mixes had dispensed with the mineral side of the equation altogether.
Mr. Loveness began by combining clays and humic particles with enzymes and soil bacteria, adding the resulting mix to milled peat moss, which on its own is unreactive and has negligible nutrient-storage capacity. Eventually he worked up a potting soil booster, as he termed it, which increased moisture retention and introduced nutrient storage and exchange capacity to plain peat. It even enabled peat to develop a crumb structure similar to that of humus-rich soil in less than one week.
In carrying out his trials, Rex Gregor used a standard commercial potting medium to which he added the booster at the rate of 1 cup to a quart of medium. All seedlings were given an ``initial shot of nitrogen to get them going,'' says Mr. Gregor, after which those with the booster were given nothing but water. The rest were given regular once-a-week applications of a soluble commercial fertilizer, as has been standard practice in the Gregor greenhouse for many years.
After a week, Mr. Gregor thought he could see the difference, and after three to four weeks there was no doubt at all. ``It was the same as between daylight and darkness,'' he says.
Tests have shown that the fertilizer value of Potting Soil Booster, as the product is now named, remains for about seven months, after which supplementary fertilizing becomes necessary. Tests with tomato seedlings at the University of Minnesota show that there is a residual beneficial effect once the seedlings have been planted out in the field. This shows up as earlier maturity and a slight increase in yield.
To the best of my knowledge there is no comparable product to Potting Soil Booster on the market at present. For more information write to Ringer CM4, Flying Cloud Drive, Eden Prairie, Minn. 55344.