My gardening season starts with my garage floor. Here, I mixed potting soil to nourish the seedlings of the season and replace the worn-out soil around the roots of indoor plants.

Good potting soil really has no special magic.

The three basic ingredients in my mixture are garden soil, mineral aggregate and organic matter. Used alone, garden soil is too dense for the container.

The mineral aggregate loosens the mixture and allows water to flow in and through easily. Vermiculite and perlite are two kinds of lightweight aggregates, the first is made of heated mica, and the second is made of heated volcanic rock. Sand and calcined clay ("cat litter") are heavier aggregates, so they are useful for top-heavy plants such as cacti.

The organic matter in potting soil acts like a sponge to absorb water, and plants can absorb water between two waterings. Organic matter can also buffer the soil, prevent drastic changes in acidity, and prevent the loss of nutrients from the bottom of seedbeds and flower pots. Sphagnum moss, sphagnum moss and coconut husk fibers (by-products of coconut processing) are organic materials that can be purchased. Compost and leaf mold are two organic materials that you can brew on your own. Compared to the materials mentioned earlier, they also provide nutrients for plants.

Some people pasteurize potting soil to reduce the threat of pests. The key is to avoid excessive heat, which brings its own problems. Put the potting soil and the embedded potatoes into the oven for baking. When the potatoes are baked, the potting soil is also baked.

Rather than pasteurize the soil, I prefer to avoid pests through careful watering, sufficient light, and other cultural conditions that make plants happy but pests sad.

The soil is good, but not necessary

It is difficult to obtain a large amount of reliable high-quality garden soil, so most commercial potting mixes do not have any real soil at all. These mixtures are made only of mineral aggregates and organic matter.

You can make this soilless mixture by sieving equal amounts of peat moss and perlite together. This mixture has no nutrients, so it is mixed in a starting feed of half a cup of dolomitic limestone and some fertilizer with a nutrient ratio of about 5-10-5. Real soil does add nutrients and other beneficial substances to the potting mix, so I prefer the traditional potting mix, which contains real garden soil.

Even if you buy potting soil, you have to prepare a few bags of certain mineral aggregates and organic materials on hand. No potting mix can meet the needs of every plant. Add additional aggregate to any mixture used for cacti or succulents, and additional organic matter to any mixture of plants such as African violets and begonias that like persistently moist soil.

For the opening ceremony of the garden season, I swept my garage floor clean, and piled a pile of 2 gallons each with garden soil, peat moss, perlite, and compost. On this mound, I sprinkled a cup of lime and half a cup of soybean meal and kelp powder. This is a mixed ingredient package, but I think plants, just like humans, benefit from a diverse diet.

I slide my garden shovel under the pile, turn it over and work on the edges until the whole clump is completely mixed, and if it looks dry, just get a little wet. Finally, I knead the mixture through a half-inch sieve and recite some mantras to complete the brewing that nourishes my seedlings and houseplants every season.

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