Cold hardiness & minimum temperature

Is Mediterranean feather grass (Stipa offneri)cold hardy? Hardiness zone & min temp

Also called Mediterranean feather grass, Offner's feather grass.

More about mediterranean feather grass

About Mediterranean feather grass

Stipa offneri · also called Mediterranean feather grass, Offner's feather grass · flowering

Mediterranean feather grass is a compact, sun-loving perennial native to dry rocky Mediterranean slopes, forming dense clumps of very fine, inrolled foliage. Slender feathery flower spikes with silky awns appear from late spring to early summer. Exceptionally drought-tolerant and suited to gravel gardens, dry borders, and Mediterranean-style plantings in well-drained soil.

Cold limit: USDA 7–10 · RHS H5 (-10–38°C)

Watch for — Crown rot in moist winters: The greatest threat to this Mediterranean species. Cold, wet, or waterlogged soils in winter quickly cause fatal crown rot. Plant in extremely well-drained conditions: gravel beds, raised areas, or sloping ground. Avoid clay soils without heavy grit amendment.

What mediterranean feather grass's hardiness rating actually means

Yes — mediterranean feather grass is genuinely cold hardy. Rated RHS H5 and USDA 7–10, 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 7–10 — 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. Mediterranean feather grass is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for mediterranean feather 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 mediterranean feather grass go outside or overwinter — and where?

Plant it out within USDA 7–10 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 mediterranean feather grass can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Mediterranean feather grass hardiness — frequently asked questions

Is mediterranean feather grass cold hardy?

Yes — mediterranean feather grass is genuinely cold hardy. Rated RHS H5 and USDA 7–10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Mediterranean feather grass is hardy across USDA 7–10; 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 mediterranean feather grass can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Mediterranean feather grass is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is mediterranean feather grass?

Mediterranean feather grass is rated USDA 7–10 and RHS H5 — Hardy in most of the UK and in cold winters.

Can mediterranean feather grass survive winter outside?

Plant it out within USDA 7–10 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 mediterranean feather 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.