Whatever your goals, shop at a quality local nursery for plants suited to your climate. If you want apples in Southern California, for instance, you should choose varieties that have lower chilling requirements than varieties suited for northern New York. For fruiting trees, look for robust, mostly unbranched 1-gallon plants called whips. For ornamentals, the main criteria, besides a malleable, easy-to-train habit, are seasonal interest (flowers, berries, foliage color) and compatibility with your chosen planting location. Suitable picks include forsythia, magnolia, flowering quince, and photinia.
Shown: The candelabra, or palmette verger, is one of several traditional forms of espalier.