BONSAI AND ROCK garden enthusiasts often grow conifers because of their year-round color, texture, and form. They show rich greens, vibrant blues, glowing golds, come with varied textures and foliage and grow in upright, weeping, and globular shapes. Keeping miniature conifers, those growing an inch (2.45 cm) or less per year, small enough for the rock garden is not difficult. However, the unchecked growth of dwarf varieties and straight species can lead to challenges. The bonsai container or rock garden trough becomes too small, nearby plants become crowded and what started as proportional and aesthetically pleasing becomes untenable. Before that happens, steps can be taken to keep conifers small, or at least minimize their size. Bonsai artists have been doing it for thousands of years.