The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
American Rock Gardens
Open winters are the most trying of all conditions. To cover or not? Well, a heavy covering is certain to finish off all rock herbs that have green, leafy, or persistent tops, unless the winter is unusually cold and dry. Plants with evergreen tops, as *Moss Phlox, are their own winter cover for the soil. The plants wholly deciduous, which die away completely to below the ground, and live and hibernate wholly below earth, as bulbs or Thalictrum, are sure to survive any winter, with or without a covering. Putting on a winter cover, other than the dried tops of the plants themselves and such leaves as blow in from the lawn, is an extra labor in placing and removing, for which no adequate return is gained. Even for the leafy-topped plants, it is cheaper and more sporting to leave off putting on any covering. It is also natural for wild flowers to go to their winter sleep without artificial covering, but nature is cruel as well as natural; and the burning which comes to leafy rock herbs some winters makes us wonder whether art, nature, or humanitarianism is to be our main guide in winter care. At any rate, the plants which are injured by an open season are as many when well covered as when left to take their own chances. Balancing the extra labor and mussy effect of covering against the probable chances of losing these treasures if left uncovered, there seems to be no real value to putting on the blankets. For the present, the Spartan method of letting each plant run its own chances with the winter seems simplest and most consistent in theory. Every winter some plants will die, but any player will miss the ball at some time in any game.
Unlike the plants of border and lawn, those of rock gardens are little troubled by insects or diseases. In their native home they are out of range of the usual garden enemies, and perhaps the pests are not aware that these little weeds are cherished now by man. There are few diseases that trouble, if the soil conditions are right for the plants; and spraying is unknown in this garden. Such common insect pests as cutworms, wire worms, and other grubs which work beneath the soil may eat the roots, if the soil is rich and garden-like, but they won't stay long in the sandy prepared soil. Violets are chewed by the caterpillars of copper butterflies; grasshoppers, crickets, and other general foliage feeders eat some plants, but the damage is not usually great. Primroses and many alpines are wholly devoured by slugs, snails, and such small animals, even mice, which find the rocks a safe refuge. Traps and poisoned bait will get some of them, but most effective is a personal hunt in the early hours. A clever scheme to protect choice weeds is to surround a section of the rock garden with a small moat of little depth of water, without drawbridge. With care at the time of construction to keep off all animal life, the worms and slugs will be forever excluded by the ring of water.
