Select wide, shallow containers. Since many succulents are wider than they are tall, planters of the same proportions are usually the most aesthetically pleasing. Terra-cotta dishes aren't the only options. For instance, with drainage holes added, the concrete birdbath at left makes a splendid container.
Start with the accent piece. "Look for a plant that will give the finished arrangement some drama," says Cohen. "You don't want all short, round pieces." He usually selects something sharply vertical. Sansevieria (snake plant) is one of his favorites, but he also uses asparagus fern, euphorbias, and even ivy trained up small trellises.
Plant contrasting companions in small groves. "You rarely find individual plants alone in nature," says Cohen. "Usually things grow in clumps, and that's how I like to arrange them."
Set plants close together. "I don't have the patience to wait for things to fill in, and with succulents you don't have to," he says. If there are gaps in a pot's planting, he fills them with cuttings from succulents elsewhere in the garden. They invariably take root. If one succulent overtakes its companions in a container, Cohen simply cuts it back and lets the others catch up.
Use succulents appropriate for your climate. The Aeoniums and echeverias that Cohen favors flourish in his mild, coastal garden but are too tender for mountain gardens and don't like harsh desert summers. Sempervivums are cold-hardy in all zones, as are many sedums and some Delosperma (ice plant). In the desert, gasteria, haworthia, and agaves are better choices.
Provide good drainage. Succulents will forgive most failures--too much or not enough water or lack of fertilizer--but they do like their roots in quick-draining soil. Use a cactus potting mix that is 50 percent pumice. If you live in a particularly wet climate, you might want to use an even grittier mix. For extra protection from winter root rot, move containers under the eaves during prolonged rainy stretches.
Water frequently when the weather warms. Succulents can survive considerable neglect, especially in mild climates, but they look better with regular irrigation in the desert and elsewhere when temperatures climb. In fact, it's hard to overwater them in summer.
Feed infrequently. Though succulents could probably get by without any fertilizer, to keep them in peak condition most succulent fanciers feed them two or three times a year with a liquid fertilizer (20-20-20, for instance) diluted to half strength.