Biennials are the quiet overachievers of the plant world—often overlooked in favor of flashy annuals or long-lasting perennials, but just as essential in a well-rounded garden. Whether you’re cultivating an ornamental border, a cutting garden, or a pollinator haven, adding biennials can bring surprise, structure, and seasonal succession to your landscape.

Let’s dig into what makes a biennial tick and explore our top 8 picks for beauty, resilience, and botanical charm.

What Is a Biennial?

A biennial plant completes its lifecycle in two years. In the first year, it produces roots, stems, and leaves—essentially storing up energy. In the second year, it flowers, sets seed, and then dies. This two-year pattern may seem slow-paced, but it allows for some of the most spectacular floral displays and robust plant growth.

How Growing Zone Affects the Biennial Cycle

In colder zones (Zones 3–6), biennials generally follow their classic routine: foliage in year one, flowers in year two. However, in warmer zones (Zones 7–10), a long growing season may cause them to skip the wait and behave more like annuals—sprouting and flowering in the same year. This can shorten their expected bloom window and disrupt reseeding rhythms. On the flip side, an early cold snap in a northern garden may kill immature plants before they establish strong roots.

Master Gardener Tip – In mild climates, sow biennials in late fall or very early spring to better mimic their natural cycle and avoid premature blooming.

Do Biennials Self-Seed?

Yes—and often enthusiastically. Once they flower and set seed in year two, many biennials drop seeds that germinate on their own. When left in place, these seeds will grow into next year’s generation, creating a rolling succession of blooms year after year without extra effort.

Master Gardener Tip – Allow seed heads to dry and scatter naturally, or collect and re-sow them in fall for best results. Mark their spots—they can be slow to emerge.

Careful What You Wish For – The Case of the Prolific Biennial

One season you’re celebrating your foxglove’s dreamy spires, the next… you’re pulling baby foxglove seedlings out of your gravel paths, cracks in the patio, and the lettuce bed.

While biennials like honesty, hollyhock, and evening primrose are generous with their seed, that generosity can quickly turn into a garden takeover. What feels like a gift the first year can become a full-blown population boom by year three—especially if you don’t intervene.

Master Gardener Tip – Deadhead selectively. Leave a few flower stalks to go to seed in intentional spots, but trim the rest before seeds mature and scatter. You’ll enjoy the beauty without the surprise army of seedlings.

Top 8 Biennials to Grow

Foxglove (Digitalis purpurea)
Towering spires of bell-shaped flowers in purple, pink, white, or apricot hues. A cottage garden icon that thrives in dappled shade.
Master Gardener Tip – Let them go to seed to keep a steady bloom cycle every year.

Hollyhock (Alcea rosea)
A classic garden beauty with tall flower stalks perfect for back borders or against fences. Looks especially dreamy in old-fashioned gardens.
Master Gardener Tip – Stake them early to support their height and protect from wind damage.

Sweet William (Dianthus barbatus)
Clusters of fringed, sweet-smelling flowers in bold reds, pinks, and whites. A pollinator magnet that thrives in cooler temps.
Master Gardener Tip – Deadhead spent blooms in year two to extend flowering time.

Parsley (Petroselinum crispum)
More than just a kitchen staple—parsley blooms attract beneficial insects in its second year.
Master Gardener Tip – Let a few plants flower to support your garden ecosystem.

Canterbury Bells (Campanula medium)
These bell-shaped beauties bloom in dreamy pastels and bring elegance to any flower bed.
Master Gardener Tip – Plant in rich, well-drained soil and mulch over winter in cold climates.

Honesty (Lunaria annua)
Also called “Silver Dollar Plant” for its papery seedpods. Purple or white spring blooms lead to decorative seed heads great for dried arrangements.
Master Gardener Tip – Sow in partial shade and enjoy both flower and seed stage beauty.

Black-eyed Susan (Rudbeckia hirta)
Technically a short-lived perennial or biennial, this bright yellow daisy-like flower brings cheerful color and attracts pollinators.
Master Gardener Tip – Start seeds early indoors for more blooms in the second year.

Evening Primrose (Oenothera biennis)
Yellow blooms open in the evening, attracting moths and night pollinators. This wildflower is also edible and medicinal.
Master Gardener Tip – Tolerates poor soil and drought—perfect for tough spots in the garden.

The Biennial Bonus

Biennials may require a little patience, but they often reward you with abundant blooms, tall flower spikes, or intricate foliage that’s worth the wait. Plus, when planned right, you can have first-year plants growing alongside second-year bloomers for continuous interest.