The routine of caring for a rock garden can best be followed by season. In early spring, before the ground is really thawed out (in cold climates), comes cleaning up. Dead tops, dead plants, and winter coverings should be removed and all made ready for new foliage and flowers soon to appear. This spring cleaning should be done early and thoroughly. As soon as the frost is out and the dead can be counted, there will always be replanting to fill in blanks. Stock should always be held in reserve in small pots in the frame for this, and new kinds can now be tried.
With the first flowers the foliage of perennial weeds will appear. There is nothing else to be done but to dig in and remove every piece of root, even if this means lifting and resetting the rock plants. It is often necessary to lift out the contents of the pocket and pick a choice plant from the mass of weed roots. There is no sense in postponing this task; the sooner done, the easier. As soon as flowers appear in any quantity, the spring work must stop, for walking on the plants and turning them about to get at the weeds rather ruins the present floral effect. From April through June (the height of the flower show) there should be nothing to be done except enjoy the display and answer the questions of visitors.
Seed gathering begins in June, for many rock plants mature their seeds early. Some seed is for sowing, some for exchange; but of many plants of easy culture the seed must be gathered while green and destroyed, or the self-sown seedlings will become too numerous. In early summer, too, comes making divisions and cuttings of such special plants of which greater increase is desired.
Annual weeds, and such perennial sorts as eluded your spring search, are now well above the foliage of the rock plants. These should be broken off close to the ground (not pulled up), for breaking will destroy the annual weeds, while the perennial sorts are to be gathered in the autumn cleaning. Loosening the soil in the summer months, even to pull a weed, allows the soil to dry out and all existing moisture must be saved. The soil surface should be entirely covered with foliage and beneath this and on the under side of the stones there will be sufficient moisture for any proper rock plant. If there be spots of bare baked soil, cover with broken peat or coarse sand.