Blacknight Hollyhock

Blacknight Hollyhock (Alcea rosea 'Blacknight')

Blacknight Hollyhock adds dramatic, near-black purple flowers on tall spires that instantly give a border a classic cottage-garden presence. It is a great way to bring height and strong color contrast to sunny beds without needing a large footprint at ground level. Blooms arrive in midsummer and stand above surrounding plants, creating a vertical layer that makes the whole planting feel more intentional. Set it in the right spot and it will return and often reseed lightly, helping you build a fuller display over time.

Distinctive Features

This upright, clump-forming hollyhock produces deep black-purple, single flowers on sturdy stalks in midsummer. The foliage is bold and green with a coarse, traditional hollyhock look that supports the tall flower spikes. Mature plants typically reach about 5 to 6 feet tall and about 2 feet wide, making them ideal for adding height at the back of borders. Flowers are also attractive to pollinators and can be cut for arrangements.

Growing Conditions

• Sun: Full sun for the strongest stems and best bloom.
• Soil: Average to fertile, well-drained soil, and avoid wet winter soils.
• Water: Medium moisture, water to establish and then provide supplemental water during extended dry spells.
• Zones: USDA Zones 3 to 9.
• Spacing: Space about 18 to 24 inches apart to improve airflow and keep plants stronger.

Ideal Uses

• Focal Point: Plant a small group as a focal point along a fence or wall where the tall flower spires can rise above the border and read from a distance.
• Back of Border: Use behind mid-height perennials to add height without blocking the view at ground level.
• Cottage Gardens: Mix with daisies, salvias, and ornamental grasses for a relaxed, classic look with strong vertical rhythm.
• Cut Flower Gardens: Grow for long stems that add dramatic height and dark color to summer bouquets.

Low Maintenance Care

• Staking: Stake in windy sites or very rich soil to keep tall stems upright.
• Cleanup: Remove spent flower stalks after bloom and cut plants back after frost or in early spring.
• Watering: Water at the base rather than overhead to keep foliage drier and reduce disease pressure.
• Airflow: Give plants space and thin nearby growth so leaves dry quickly after rain.

Why Choose Blacknight Hollyhock?

• Dark Flower Color: Deep black-purple blooms create bold contrast that elevates both classic and modern palettes.
• Vertical Impact: Reaches about 5 to 6 feet tall to add height and structure where the garden needs it most.
• Seasonal Drama: Midsummer bloom brings a strong, finishing layer to sunny borders.
• Pollinator Friendly: Flowers help draw butterflies and hummingbirds into the garden.

Blacknight Hollyhock is most effective when planted in a few repeats, letting the tall spires form a dramatic backdrop rather than a single spike. Pair it with lower, mounding plants to cover the base and keep the planting looking full from top to bottom. Provide sun, drainage, and decent airflow, and it will reward you with a midsummer show that feels classic and unforgettable. If you want height with a dark, moody edge, this plant fits beautifully.