Use perennials as backbones, annuals as fillers. Sisters Specialty Gardens uses flowering shrubs and perennials as mainstays in beds and borders, filling in around them with annuals for quick and easy color. A pathway, for example, is accented by flowering shrubs such as Westringia fruticosa 'Morning Light' and deep purple butterfly bush (Buddleja davidii). There are also white 'Iceberg' roses, penstemons (P. x gloxinioides), and dwarf Agapanthus 'Peter Pan'. Annual nemesias in white, pink, and blue border the path, where they can be easily reached and swapped out. "Annuals bloom for six months and can be replaced at minimal cost," Gousha explains. Low, mounding chamomile and creeping thymes grow between the nemesias.
Choose easy-care plants wherever possible. For the hot, dry slope pictured, Sisters mixes tough, unthirsty perennials, mostly in purples, pinks, and grays. Among them: Armeria maritima, with globular pink flowers; Artemisia 'Powis Castle', with silvery foliage; purple bearded iris; lavender (Lavandula dentata, L. x intermedia); pride of Madeira (Echium candicans), with blue-purple flower spikes; salvias; Santa Barbara daisy (Erigeron karvinskianus), with white, daisylike flowers; Santolina chamaecyparissus, with yellow, buttonlike blooms; society garlic (Tulbaghia violacea), with pale lavender-pink blooms; and yarrow (Achillea millefolium). Horizontal pathways and rock walls help hold the slope.
Tuck in flowers for cutting. To bring the beauty of the garden indoors, Sisters finds places to add cutting flowers for use in bouquets. Against a trellis beside a driveway in one garden, the women planted sweet peas that bloom from mid-January or early February into May, depending on the weather. "In spring, we harvest often," Longmire says. "The more you pick and deadhead, the longer the plants produce flowers." McFadden adds: "A simple jar or white earthenware pitcher is perfect for displaying them." Sisters starts sweet peas in midfall, sowing seeds about 2 inches apart in well-prepared soil.
Plant seasonal color in pots. To brighten entries and soften hardscapes such as patios and poolsides, the women fill pots and bowls with annuals twice a year: in October for fall through spring color, and in May for summer color.
They combine two or three different types of plants per pot ("Less is more," Gousha says). Johnny jump-ups, pansies, and violas in shades of purple and violet might fill pots during the cool season. In May, they're replaced with warm-season bloomers such as white African daisies (Osteospermum Symphony Series), lavender bacopa, pale pink geraniums, hot pink million bells (Calibrachoa hybrids), and blue and white nemesias.
Before planting, Sisters fills pots with four parts potting soil to one part worm castings (available at nurseries). To achieve fullness fast, they pack the pots with plants ― a flat of 4-inch annuals (16 plants total) for a 2-foot-diameter pot, for instance. Plants get water as needed (about once a week in winter, twice weekly in summer) and are fed every two weeks with liquid fertilizer.
Cover bare soil. Nothing makes a planting look unfinished or immature like bare soil around it. Sisters lays lime-colored Scotch moss (Sagina subulata) over the soil beneath potted topiaries or other plants in containers (such as the violas pictured above). A blanket of moss lends a weathered, Old World appeal to pots. Use a knife to cut pieces of moss from nursery flats, trimming them to fit your container. Moss needs regular watering and occasional feeding with liquid fertilizer.
Sisters Specialty Gardens: (760) 473-0234.