Illustration
Nigra
Alcea rosea 'Nigra'
Nigra blooms from June through August.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Nigra
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 3–8. Expect it to reach about 6 ft tall and 2 ft wide at maturity, in roughly 2 years (not yet checked).
What was checked
Mature height and spread, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not, and each fact above says which. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Nigra
Plant Nigra in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 5, the middle of its hardy zones 3 to 8, spring means April to June and fall means August or September. Once settled, it blooms from June to August.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 5, the middle of this plant's hardy range, start with zone 5 in April. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Nigra get?
6 fttall5 ft 7 inan adult2 ftwideSee Nigra in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Nigra
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Nigra about 2 ft apart, center to center, so each plant has room to reach its full width.
Add Nigra to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Nigra's height, spread, hardiness zones, sun and trait tags were checked against 15 published sources on July 31, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- Missouri Botanical GardenAlcea rosea 'Nigra'height, spread, hardiness zones, sun, years to mature size and trait tags
- Missouri Botanical GardenAlcea roseaheight, spread, hardiness zones, sun, years to mature size and trait tags
- Perennials.com (Heritage Perennials)Heritage Perennials / perennials.com (Alcea rosea 'Nigra')height, spread, hardiness zones, sun, years to mature size and trait tags
- plants.oaklandnursery.comOakland Nurseries (NetPS Plant Finder database, Black Hollyhock)height, spread, hardiness zones, sun, years to mature size and trait tags
- depts.ttu.eduTexas Tech University Plant Database (Hollyhocks, Alcea rosea)height, spread, hardiness zones, sun and trait tags
- harvestnestseeds.comHarvestNest Seeds (Hollyhock Nigra Seeds)height, hardiness zones, sun, years to mature size and trait tags
- bloomoutlet.comBloom Outlet (Alcea rosea var. 'Nigra' Chocolate Black Hollyhock)height, hardiness zones, sun and trait tags
- NC State ExtensionAlcea roseaheight, spread, sun and trait tags
- RHSRoyal Horticultural Society (Alcea rosea 'Nigra')height, spread, sun and years to mature size
- seedterra.comSeedTerra (Hollyhock Nigra Seeds - Alcea Rosea)height, hardiness zones, sun and trait tags
- RHSRoyal Horticultural Society (Alcea rosea)height, spread and sun
- University of Arkansas ExtensionHollyhock, Plant of the Weekheight, sun and years to mature size
- University of Illinois ExtensionHollyhock, Alcea roseaheight, sun and trait tags
- University of Illinois ExtensionIllinois Extension, Good Growing (How to grow and care for hollyhocks)height, sun and years to mature size
- herboo.comHerboo (Hollyhock 'Nigra' Seeds)sun and trait tags
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Nigra
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
Handling the foliage can cause skin irritation or contact dermatitis in some people, and mild stomach upset in animals that eat it. Wear gloves. per Cornell
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Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.