Alcea rosea ‘Nigra’ Seeds | Black Hollyhock
LATIN NAME: Alcea rosea ‘Nigra’
COMMON NAME: Black Hollyhock
Plant Profile
Where the double sorts pile on petal, the black hollyhock keeps the simple open flower: five broad petals around a pale central boss of stamens. The drama is purely in the colour, which deepens from maroon at the petal base to a near-black rim, and the effect is strongest in full sun when the pigment is most concentrated and the petal surface takes on an almost velvet sheen.
Dark hollyhocks travelled from the eastern Mediterranean into western gardens during the great plant exchanges of the sixteenth century, and the ‘Nigra’ selection has been kept by seed savers ever since for its reliable depth of colour. It remains one of the few truly dark flowers a gardener can raise from seed without special effort, which is why it anchors so many “black” themed borders.
Holding the colour means roguing any plant that flowers red or pink, since the dark trait is not perfectly fixed and lighter off-types appear each generation. Seed lines labelled Nigra are the result of that quiet selection, which is why a named strain stays darker than random saved seed and why the darkest spikes are worth saving for the next year’s sowing.
Because the flowers stay open, the plant earns its place twice: first as a bee magnet through the height of summer, then as a source of the flat round seed heads shaped like a cheese wheel that give hollyhock its old name and feed finches as they ripen.
Science & Biotechnology
The black look is a biochemistry story: the plant loads its petals with delphinidin-based anthocyanins, the same class of pigment that blues a blueberry, only at a concentration and pH that push the hue toward black. The same chemistry darkens a black pansy or a black tulip, so Nigra is part of a small club of flowers that fake a colour no plant pigment truly makes.
Uses & Benefits
The pale eye at the flower’s heart is not a separate part but the cluster of unfertilised stamens showing through, and it sharpens the illusion of black by contrast. Bees find the open shape easy to work, which makes Nigra a better pollinator plant than the petal-clogged doubles, and the same open flower is a host for the caterpillars of the painted lady butterfly.
Growing from Seed
The petals yield a soft grey-violet dye on wool and silk, deeper when the water is slightly alkaline, and dried flower heads are used in everlasting arrangements where the dark tone reads as near-neutral against brighter blooms. The seed discs, once dry, are easy to collect and store for the next season’s sowing, and children still thread them as the old “cheeses” of the garden.
As a biennial, the plant needs its first season as a leaf rosette, so sow early enough for strong roots before winter and you will be rewarded with the tallest, darkest spires the following summer.
Sow in modules on loam and sand, then thin to leave one seedling per cell once the first true leaf shows, because crowded roots produce weak, branching stems that flop. Plant out when the rosette is a hand’s span wide, setting the crown just at soil level and firming the soil so the taproot drives straight down.
Give a low-nitrogen feed as the spike forms and water at the base to keep the leaves dry, since hollyhock is prone to rust in humid weather, a fungus that speckles the foliage with orange pustules. Remove the lower leaves at first sign of spotting and the plant will usually carry its dark flowers clean to the top, where they show best against the sky. The fungus, Puccinia malvacearum, is the classic hollyhock rust and overwinters on the old basal leaves, so clearing the debris in autumn is the best prevention.
Our Take
I set black hollyhock where the evening light catches the near-black blooms, beside marshmallow for a quiet Malvaceae grouping and burgundy okra for a matching deep tone. A hibiscus mutabilis in a pot nearby extends the dark-flowered theme upward.
Related Reading
If Black Hollyhock appeals to you, these related plants are worth a look: