The genus Digitalis, commonly known as foxglove, features dramatic and instantly recognizable flowers, characterized by tall, spire-like stalks covered in bell-shaped blossoms. These stately plants add stunning vertical accents to any garden space, attracting pollinators like hummingbirds and bees. However, standard foxgloves do not bloom all summer; the most common varieties have a distinct life cycle that limits their flowering window. Understanding their biology and utilizing specific gardening techniques can help maximize the duration of their spectacular display.
Understanding the Foxglove Life Cycle
Most foxgloves do not provide continuous summer color because they are classified as biennials. A biennial plant completes its entire life cycle over two years, focusing on growth in the first season and reproduction in the second.
In the first year, the plant dedicates energy to developing a strong root system and forming a low-growing cluster of leaves known as a basal rosette. This vegetative growth stores the energy needed for the next stage of its life. The plant remains in this rosette form through the first winter, preparing for its finale.
In the following spring (the second year), the stored energy is channeled into producing the singular, towering flower spike. Once this central stalk has bloomed and successfully set seed, the plant’s life cycle is complete, and the entire structure dies. This post-flowering senescence is why a single standard foxglove cannot bloom from spring through the end of summer.
The Typical Foxglove Bloom Window
For the standard biennial foxglove, the flowering period typically begins in late spring and extends into early to mid-summer. Depending on the local climate, this usually translates to a bloom window starting around May and lasting through June or early July. The show is intense but relatively brief.
Each individual flower spike is packed with dozens of tubular blossoms that open sequentially from the bottom of the stalk upward. This staggered opening ensures the entire spike remains in color for several weeks, creating the illusion of a prolonged bloom. However, once the blossoms on the main spike have faded, the plant has finished its reproductive task for the season.
Extending the Bloom Period Through Pruning
Although the plant’s biology dictates a finite bloom period, gardeners can use specific pruning techniques to encourage a second, smaller flush of flowers. This practice, known as deadheading, involves removing the spent central flower stalk before the plant channels energy into seed production. Removing the primary stalk forces the plant to redirect resources into vegetative growth and new, smaller flowering shoots.
To properly deadhead, cut the main flower spike down to just above the small, emerging side shoots or near the basal rosette of leaves. This action prevents seed formation, which would signal the plant to shut down for the year.
This energy conservation encourages the development of secondary flower spikes, which emerge from the base of the plant or the leaf axils. These secondary spikes are shorter than the initial stalk but will bloom several weeks later, extending the display into mid or late summer. For continuous color year after year, gardeners can also employ sequential planting, ensuring a fresh batch of second-year plants is ready to bloom each spring.
Selecting Varieties for Extended Color
The surest way to achieve extended color beyond the typical biennial schedule is to select specific species and modern hybrid cultivars bred for longevity. Breeders have successfully developed Digitalis varieties that bypass the two-year limitation of the common foxglove. These varieties either bloom in their first year or behave as true, short-lived perennials.
First-Year Bloomers
First-year flowering varieties, such as the ‘Dalmatian’ or ‘Camelot’ series, can be started from seed early and bloom in the same season. Although they may still be technically biennial, their ability to flower in year one means a quicker, more reliable show.
Sterile Hybrids
Sterile hybrids, such as the ‘Illumination’ series, do not set seed. Because they cannot complete their reproductive cycle, these plants continue to produce flowers for a significantly longer period, sometimes blooming from spring into autumn.
True Perennials
For a true perennial presence, gardeners can turn to species like Digitalis grandiflora (Yellow Foxglove) and Digitalis ferruginea (Rusty Foxglove). These varieties are genuine perennials, meaning they live for multiple seasons (often three to five years) and return each year to bloom, offering a dependable, long-term source of color.