The majestic Casablanca lily grows on tall slim stems with comparatively small foliage, leaving space for accent underplantings that complement the crisp white blooms. The best plants for underplanting lilies are shallow-rooted perennials and annuals that have a full and cascading growth habit. Annuals and perennial plant choices each have their upside. Annuals tend to root less deeply so they are easy to remove and replace, while planting perennials will reduce the need for soil disruption around the bulbs each year. Look for complementary or contrasting color and texture and plant in the spring just before or just as the bulb foliage begins to peek through the soil. Choose plants that, like Casablancas, will thrive in lightly filtered sunlight.
Annuals and bedding plants bring bursts of color over varying textures of foliage. Some annual species to consider as underplanting for your Casablanca lilies include petunia, impatiens, lathyrous, lobelia, nicotiana, pansy, verbena, omphalodes and pelargoniums.
Perennials vary greatly in growth habit and form. When underplanting tall, spindly lilies, some fullness can help disguise sparse areas. Consider planting one or more of these perennials alongside your bulbs: geraniums, achillea, aster, alchemilla, euphorbia, amsonia, boltonia, crambe, dianthus, dicenta, astrantia or anchusa.
Underplanting with Ground Covers
Ground covers are a lower growing choice than most annuals or perennials, but that can provide a lush and dramatic backdrop for the large white lilies. Some ground covers flower, while others simply have interesting foliage or mounding habits and will work to complement or contrast with the lilies. In ground covers consider Antennaria, lambs ear, bergenia, cordifolia, brunnera, campanula, elysium, phlox, vinca, ajuga or pachysandra.