🌸 Nigra Hollyhock

Alcea rosea 'Nigra'
The black hollyhock: near-black, single flowers on towering spires, the hollyhock that looks like velvet in the sun.
Sun
Full sun
Time to bloom
Second summer; near-black single flowers on 5- to 8-foot spires
Spacing
12-24 inches apart
Soil pH
6.0-7.5, rich and well-drained
Zones
Zones 3-9 (Florida: North and Central trial; see note)

What it looks like

Nigra Hollyhock (Alcea rosea 'Nigra') — Alcea rosea nigra
Alcea rosea nigra. Photo: Øystein Hellesøe Brekke, CC BY 3.0.
Nigra Hollyhock (Alcea rosea 'Nigra') — Althaea rosea var.nigra Blck Hollyhock შავი ტუხტი
Althaea rosea var.nigra Blck Hollyhock შავი ტუხტი. Photo: Lazaregagnidze, CC BY-SA 3.0.
Nigra Hollyhock (Alcea rosea 'Nigra') — Malva negra - Alcea rosea var. nigra - Hollyhock (7448054488)
Malva negra – Alcea rosea var. nigra – Hollyhock (7448054488). Photo: jacilluch, CC BY-SA 2.0.

Why this variety

Nigra is the hollyhock for gardeners who want drama without double ruffles: tall, 5- to 8-foot spires of single, near-black flowers — so dark purple they read as black — with a contrasting pale center, blooming in the second summer on a biennial plant. Black flowers are rare in the garden, and Nigra’s velvety, near-black petals against a sunny fence or pale wall are a showstopper: bees love the open singles, photographers love the contrast, and neighbors ask what it is. It is the hollyhock that looks expensive while costing seed-packet money.

The trade-off is rust and biennial patience: hollyhocks are biennials — first year a rosette, second year a spire — and they suffer rust in humid climates, with orange pustules on leaves that weaken the plant. Give Nigra full sun, air circulation, rich well-drained soil, and room, remove rusted leaves promptly, and let it self-seed for next year’s spires. Stake tall spires in windy sites, and do not plant it in shade or wet soil and expect a tower.

If you are new to choosing between cultivars, the Varieties Matter guide explains why the name after the plant matters as much as the plant itself. Nigra is a perfect example: it is not just a hollyhock in the abstract, it is a hollyhock with a specific job, a specific history, and specific strengths.

Florida honesty: hollyhock is a North and Central Florida trial, not a statewide perennial — Florida humidity supercharges rust, and South Florida heat shortens its life. In North and Central Florida, plant Nigra in full sun with air circulation, in rich well-drained soil, remove rusted leaves at the first orange spot, and treat it as a cool-season biennial that self-seeds. In South Florida, treat it as a seasonal annual and do not mourn it in summer.

How to grow

Sow seed in summer for bloom the second year, or start indoors early for first-year bloom from dwarf types — hollyhock is a biennial by nature, first year a rosette, second year a spire. Set plants in full sun and rich, well-drained soil, work worm castings into the bed at planting, and give them air circulation to fight rust. Stake tall spires in windy sites, and let a few plants self-seed for next year’s spires.

Set plants 12-24 inches apart in soil with a pH around 6.0-7.5. Work worm castings into the bed at planting and mulch to hold moisture. A well-fed hollyhock plant rewards that care directly: steadier growth, better bloom, and a show that actually shows up.

Water & feeding

Keep soil evenly moist but never waterlogged — hollyhocks want steady moisture and good drainage, not swamp and not drought. Water at the soil line, mulch to hold moisture, and feed moderately: castings at planting plus a balanced organic feed in spring. Avoid overhead watering where rust is a problem.

Common problems

  • Rust in humid climates — orange pustules on leaves; remove affected leaves promptly, space for air, and avoid overhead watering.
  • Biennial patience — hollyhocks bloom in year two (except early-sown dwarfs); sow yearly for continuous spires.
  • Flopping tall spires in wind — stake tall forms in windy sites; dwarf forms need less staking.
  • Seedling reversion — seedlings of doubles often revert to singles; deadhead for purity or welcome the mix.
  • Short life in hot, wet summers — heat plus humidity shortens hollyhock life; in warm zones, treat it as a cool-season biennial.

Harvest

Cut spires for tall bouquets in summer, when flowers are fully open — hollyhock flowers last a few days in water and suit dramatic, cottage-style arrangements, though tall spires need a tall vase and a steady hand. Deadhead lightly for rebloom on dwarfs, let tall types self-seed for next year’s spires, and cut back spent plants in fall.

Nerdy fact: Nigra’s near-black is not black pigment — no flower makes true black. It is anthocyanin packed so densely into each petal that almost no light escapes, the same trick that makes black tulips and black pansies look black. Hold a Nigra petal to strong light and it glows deep purple: the black is an illusion made of very, very dark purple.

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Saving seeds

Nigra is the hollyhock for gardeners who want drama without double ruffles: tall, 5- to 8-foot spires of single, near-black flowers — so dark purple they read as black — with a contrasting pale center, blooming in the second summer on a biennial plant. Black flowers are rare in the garden, and Nigra’s velvety, near-black petals against a sunny fence or pale wall are a showstopper. As an open-pollinated strain it comes true from seed: sow seed in summer for bloom the second year — hollyhock is a biennial by nature, first year a rosette, second year a spire — and let a few plants self-seed for next year’s spires. The full method is in the Saving seeds section of the Hollyhock guide.