Hollyhock (Alcea rosea 'Nigra')

Overview

Alcea rosea ‘Nigra’, commonly known as the black hollyhock, is an indispensable architectural plant in the perennial border. Valued for its dramatic, deep, almost black blooms, this cultivar brings striking contrast to traditional cottage garden designs. The flowers ascend rigid, towering vertical spikes, creating a powerful visual statement throughout the mid-summer months.

This herbaceous perennial thrives best when situated in full sun, providing the necessary energy for its massive vertical growth, typically reaching 5 to 8 feet tall. Although sometimes short-lived, the ease with which Alcea rosea ‘Nigra’ self-seeds ensures that colonies can persist in the garden for many years, creating enduring structure.

Beyond their commanding height, these hollyhocks are appreciated for their classic appeal and tolerance for various soil conditions, provided drainage is adequate. Incorporating Alcea rosea ‘Nigra’ into your garden plan guarantees a bold, dark focal point that captures the charm of old-world plantings.

Fast Facts

• Plant Family: Malvaceae
• Plant Type: Herbaceous perennial
• Hardiness Zones: USDA Zones 2-9
• Size at Maturity:
  • Height: 5-8 ft
  • Spread: 1.5-2 ft
• Bloom Time: July to August
• Bloom Description: Dark maroon, almost black
• Sun Exposure: Full sun
• Water Needs: Medium
• Maintenance Level: Medium

How to Grow

For the best results with Alcea rosea ‘Nigra’, plant seeds in late summer (August or September) if you desire bloom the following year, as they establish best when overwintering. Ensure planting occurs in average, well-drained soil, as hollyhocks absolutely will not tolerate wet winter soils, which invites root issues. While they prefer full sun, this variety can tolerate some light shade, although flowering may be slightly reduced.

Watering should be moderate; aim for consistently medium moisture during the active growing season, especially in hotter climates. Fertilization is often unnecessary due to their robust nature, but a balanced feed in spring can support tall growth. Though the towering flower spikes are generally rigid, be prepared to provide staking for your Alcea rosea ‘Nigra’ if it is planted in an area heavily exposed to strong winds.

Remember that although this plant is considered a biennial or a short-lived perennial, it is an enthusiastic self-seeder. Allowing fading flower heads to remain until late autumn can result in new plants emerging the following spring, maintaining your established colony of hollyhocks year after year. A simple annual clean-up or thinning of volunteers maintains plant health.

Landscape Uses

The sheer verticality of Alcea rosea ‘Nigra’ makes it a superb tool for adding architectural drama to garden designs. They are ideally suited for the background of cottage gardens or along the sunny side of fences and walls where their height is best utilized. Use the almost-black blooms to create stunning negative space against bright pinks, vivid blues, or pale yellows.

Consider this hollyhock for its ability to naturalize gently, filling gaps or creating informal drifts along property lines. While they look magnificent paired with softer textures like ornamental grasses or large-leafed hostas (planted where they receive light shade according to hosta needs), they perform best when given the high sun requirements necessary for their best bloom.

Standout Features

Flower Qualities

• Showy

Noteworthy Characteristics

Alcea rosea, commonly called hollyhocks, are old garden favorites. The flowers grow on rigid, towering spikes or spires which typically reach a height of 5-8’ tall and usually do not require staking. Foliage features large, heart-shaped (3, 5 or 7 lobes), rough lower leaves which become progressively smaller toward the top of the spire. ‘Nigra’ is a classic hollyhock whose deep maroon blooms look almost black.

Tolerances

• Rabbit
• Black Walnut

Potential Problems

Foliage of Alcea rosea ‘Nigra’ is susceptible to fungal diseases like rust, leaf spot, and anthracnose, which can make the leaves appear tattered. Furthermore, pests such as spider mites and Japanese beetles can occasionally be problematic, attacking the leaves more frequently than the dramatic black flowers. Maintain good air circulation by spacing plants properly and avoid overhead watering to reduce fungal spore spread. Promptly remove and destroy any heavily infected leaves to manage disease progression.

Frequently Asked Questions

What hardiness zones is Hollyhock suitable for?

Alcea rosea ‘Nigra’ is highly resilient and suitable for USDA Zones 2 through 9.

How large does Alcea rosea ‘Nigra’ grow?

This impressive hollyhock typically reaches a mature height between 5 and 8 feet tall with a spread of 1.5 to 2 feet wide.

When does Hollyhock bloom?

Alcea rosea ‘Nigra’ generally blooms across the middle of the growing season, from July through August, showcasing its unique dark maroon, almost black flowers.

What sun exposure does Alcea rosea ‘Nigra’ need?

It requires full sun exposure for optimal growth and abundant flowering display.

Conclusion

The nearly black coloration of Alcea rosea ‘Nigra’ guarantees a unique and dramatic element unattainable with standard green foliage plants. This classic Hollyhock provides excellent vertical accent and cottage garden charm with reliable, albeit medium, maintenance. Ensure your site offers several hours of direct sun and well-draining soil to successfully incorporate this towering favorite into your summer landscape plan.

Companion Planting

Selecting appropriate companions can enhance the visual impact of Alcea rosea ‘Nigra’ while managing its potential disease susceptibility. Because hollyhocks are tall and benefit from good air circulation, pair them with shorter, sun-loving perennials that share similar medium water needs. Consider plants like ornamental sage (Salvia nemorosa cultivars) or catmint (Nepeta) in the foreground; their mounding habits contrast beautifully with the vertical spires of the hollyhock. Also, planting flowers that bloom earlier or later in the season, such as peonies or sturdy daisies, ensures continuous interest once the Alcea rosea ‘Nigra’ finishes blooming.

Design Ideas

The dark, intense coloration of this specific Hollyhock makes it a perfect fit for Moon Gardens or highly stylized, modern cottage borders where dramatic contrast is desired. Plant groups of three or five Alcea rosea ‘Nigra’ against a light-colored fence or structure to maximize the intensity of the dark maroon blooms, making them appear even blacker in the summer light. For a true cottage feel, allow them to mingle near informal groupings of roses or towering sunflowers, embracing the slightly wild, abundant aesthetic that hollyhocks inherently provide.