Pollination & Durability of Foxgloves

Floral Adaptations

• Foxglove flowers tend to mass on one side of the stalk. This make for a great garden display and also allows bumblebees more efficiency in gathering nectar and pollen. The flower width matches the body size of the bee. The flowers have a prominent lower lip marked with speckles that serve as bumblebee landing guides. From this landing platform, the bumblebee pushes inward to reach the pool of nectar at the bottom of the flower. In so doing, their bodies contact the pollen-bearing anthers on the top side of the flower, transferring the pollen to the female stigma on another flower so that seeds can form.

Other Flower Visitors

• Foxgloves arose in Old World areas where hummingbirds do not occur, so bumblebees alone pollinate the flowers in their native habitats. In North American gardens, hummingbirds visit foxglove flowers and can pollinate them, even though the primary pollinators are still bumblebees. The attraction for the hummingbird is the sugar-rich nectar. Occasionally, other kinds of bees will visit the flowers but aren't effective pollinators.

Sturdiness

• The tallest growing foxgloves are common foxglove (Digitalis purpurea) and rusty foxglove (Digitalis ferruginea), which both have flower stalks that can reach 5 to 6 feet tall. The sturdy stems sometimes need staking to remain upright. Common foxglove has limited invasiveness in some habitats. Other species with shorter stems, such as yellow foxglove (Digitalis grandiflora) and mullein foxglove (Digitalis thapsi), have shorter stems to 3 feet tall and don't need support. Sturdy biennial foxgloves grow a basal rosette the first year and flowers the second year. The hybrid strawberry foxglove (Digitalis x mertonensis) lasts longer than two years, growing in U.S. Department of Agriculture plant hardiness zones 3 through 9.

Garden Presence

• Foxgloves have durable garden presence. Bloom periods are extensive, giving long color to the garden, and you can cut back the main stem after flowering for rebloom. To reseed for continued garden presence, leave the flower stalks until after seeds mature and self-sow. Some species native to Mediterranean areas do well in drier, hotter climates, and others that grow as forest understory plants do best in areas with cooler and moister summers. Species for cooler areas are common foxglove and rusty foxglove, both hardy in USDA plant hardiness zones 4 through 8, and yellow foxglove in USDA zones 3 through 8. For warmer areas, consider mullein foxglove, growing in USDA zones 5 through 9, and Grecian foxglove (Digitalis lanata), hardy in USDA zones 4 through 9.