The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Rockweler Rockgardens

And so, in addition to exceptional drainage, we must add to our analysis an abundant moisture supply.

Plant Food. If we inquire still further into the life secrets of these little plants, and attempt to seek out their food sources of sustenance, we immediately strike a rock, both figuratively and literally. Most of our common garden plants would starve to death in the soil in which they thrive. And, vice versa, many of these little plants cannot long survive a diet of manure and fertilizers on which our garden plants grow lustily—although some of them, it must be confessed, will take to the change like ducks to water.

And so it is apparent that a large supply of plant food, as we prepare it for our long domesticated garden flowers and shrubs, is one of the things that is not essential for the class of plants under consideration.

So, having analyzed the soil conditions which nature provides, let us see what we can do toward synthesizing, or putting together, a manufactured soil which will come somewhere near duplicating it.

A GENERAL PURPOSE ROCK-GARDEN SOIL

The gardener knows that there is nothing like coarse, gritty sand for increasing the drainage properties of a soil. He uses it in his cutting bed, in the soil he mixes for potting. So sand will be one of the ingredients.

The roots of rock-garden plants, as we have seen, like to cling around the moist surfaces of bits of stone buried in the soil, while the leaves rest upon those pieces which work their way to the surface, thus avoiding direct contact with the dirt. So another ingredient will be stone chips. Ordinary crushed stone, such as is used for surfacing roads, is suitable; this can be readily procured in most sections. If not, bank gravel, preferably not too fine or smooth, and not "washed," will serve as a substitute.

For our third ingredient, we add humus or decayed vegetable matter, which is found almost invariably in soils in which rock plants grow. This material holds an additional supply of moisture, besides furnishing some plant food. For supplying humus, I like granulated peatmoss. It is so slightly acid that only the extreme lime-loving plants object to it, and it absorbs and holds more moisture than any similar material. Moreover, it is both pure and absolutely free from weed seeds, an advantage which cannot be overemphasized in rock-garden planting. Peatmoss is now readily obtainable anywhere; but if you do not happen to have it, finely sifted leafmold will serve. Commercial humus has more of a tendency than either of the above to get wet or soggy.