Cold hardiness & minimum temperature

Is Black-Headed Fountain Grass (Pennisetum alopecuroides 'Moudry')cold hardy? Hardiness zone & min temp

Also called Black-headed fountain grass, Black fountain grass, Moudry fountain grass.

More about black-headed fountain grass

About Black-Headed Fountain Grass

Pennisetum alopecuroides 'Moudry' · also called Black-headed fountain grass, Black fountain grass · flowering

A compact, warm-season ornamental grass from eastern Asia, selected for its distinctively dark — nearly black — bottlebrush flower spikes that appear 3–5 weeks later in the season than most other fountain grass cultivars. It forms a tidy, arching mound of glossy green foliage that turns golden in autumn, and thrives in full sun with well-drained soil. The single most critical care point is that 'Moudry' self-seeds prolifically in warmer climates (Zone 7 and above), so removing spent seed heads promptly prevents naturalisation. Fountain grass (Pennisetum alopecuroides) is considered non-toxic to cats and dogs by the ASPCA.

Cold limit: USDA 6-9 · RHS H5 (-20 to 40°C)

Watch for — Poor flowering in shade or cold soils: Insufficient sunlight or planting in cold, poorly draining soil delays or prevents the characteristic dark flower spikes; ensure a warm, sunny, sheltered site and divide congested clumps every 3–4 years.

What black-headed fountain grass's hardiness rating actually means

Yes — black-headed fountain grass is genuinely cold hardy. Rated RHS H5 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 6-9 — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about −15 to −10 °C. Black-Headed Fountain Grass is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for black-headed fountain grass as it gets too cold:

It tolerates winter lows to about −15 to −10 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can black-headed fountain grass go outside or overwinter — and where?

Plant it out within USDA 6-9 and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when black-headed fountain grass can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Black-Headed Fountain Grass hardiness — frequently asked questions

Is black-headed fountain grass cold hardy?

Yes — black-headed fountain grass is genuinely cold hardy. Rated RHS H5 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Black-Headed Fountain Grass is hardy across USDA 6-9; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature black-headed fountain grass can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Black-Headed Fountain Grass is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is black-headed fountain grass?

Black-Headed Fountain Grass is rated USDA 6-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can black-headed fountain grass survive winter outside?

Plant it out within USDA 6-9 and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to black-headed fountain grass below its minimum temperature?

It tolerates winter lows to about −15 to −10 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.