The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
American Rock Gardens
In periods of a month without rain, some of the rock plants will become wilted. Either the soil preparation was not carefully done or these are bog plants. Rebuild the pockets next autumn and shift the plants. Watering with the hose is legally allowable, though not a natural process, but if squirted on too forcibly the water digs up plants and stones and washes away the soil. If the site is really desert-like, and other than Carcti and Sedums are desired, it is simple and effective to install sub-irrigation by means of leaking water pipe or tile during construction.
With the first cool of autumn and moisture of rains, there is quite a display of bloom and much stem growth for next year. After frosts have closed the season, the heavy weeding of perennial pests must be undertaken. Now every piece of
weed will have a visible top, and there is no excuse for not getting them wholly and forever removed.
Some rock plants will have grown too well by roots or by seed, and these should be thoroughly thinned; others will have too much top and smother their neighbors. For such cases a big knife should give a severe Dutch cut or a pruning of the tangle. For better bloom the next spring, this cutting should be done in early summer after bloom; but the foliage effect is injured until new growth has come out. Some replanting must be done in the autumn (late August to October), but where winter heaving is severe, it is better to set out in the spring. With a mulch of peat or dry hay, large potted plants will survive any winter safely.
Top left.—Alpine Poppy, Papaver alpinum. Top right.—
Tweedy Bitter-root, *Lcuisia tweedyi. Bottom Left.—Stem-
less Gentian, Gentiana acaulis. Bottom right.—Rock Primrose,
Primula acaulis
PLATE VI.—ALPINE HERBS IN CULTIVATION
Top left.—Aubrietia Wallcress, Arabis aubrietioides. Top right.
—Wallcrcss, Arabis albida. Bottom left.—Persian Stonecress.
Aethionetna persicum. Bottom right.—Evergreen Candytuft,
lberis sempervirens
PLATE VII.—WALL HERBS IS THE GARDEN
Lastly comes the decision as to winter protection of special coverings. Short is this paragraph —omit all special coverings. If the plants have good tops or a mulch of peat and sand about the crowns, and construction below is as it should
have been, any rock plant will come through the winter safely, if at all hardy in that latitude. No covering at all is easiest and best. It is better to put the plants at the mercy of an open winter than to smother with blankets of hay, leaves, or manure. None of these fall in the winter on the slopes of Pikes Peak; yet the mountain plants survive.
