Cold hardiness & minimum temperature

Is Big Blue Lilyturf (Liriope muscari 'Big Blue')cold hardy? Hardiness zone & min temp

Also called Lilyturf, Monkey Grass, Border Grass.

More about big blue lilyturf

About Big Blue Lilyturf

Liriope muscari 'Big Blue' · also called Lilyturf, Monkey Grass · houseplant

Big Blue Lilyturf is a clump-forming grass-like perennial with arching dark green strap leaves and violet-blue flower spikes in late summer. Indoors it thrives in bright indirect to medium light with consistent moisture. It contains steroidal saponins and is toxic to dogs and cats.

Cold limit: USDA 5-10 · RHS H5 (10-25°C)

What big blue lilyturf's hardiness rating actually means

Yes — big blue lilyturf is genuinely cold hardy. Rated RHS H5 and USDA 5-10, 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 5-10 — 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. Big Blue Lilyturf is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for big blue lilyturf 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 big blue lilyturf go outside or overwinter — and where?

Plant it out within USDA 5-10 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 big blue lilyturf can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Big Blue Lilyturf hardiness — frequently asked questions

Is big blue lilyturf cold hardy?

Yes — big blue lilyturf is genuinely cold hardy. Rated RHS H5 and USDA 5-10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Big Blue Lilyturf is hardy across USDA 5-10; 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 big blue lilyturf can survive?

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

What hardiness zone is big blue lilyturf?

Big Blue Lilyturf is rated USDA 5-10 and RHS H5 — Hardy in most of the UK and in cold winters.

Can big blue lilyturf survive winter outside?

Plant it out within USDA 5-10 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 big blue lilyturf 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.