Cold hardiness & minimum temperature

Is Loscosi's Thyme (Thymus loscosii)cold hardy? Hardiness zone & min temp

Also called Loscosi's thyme, Ebro thyme.

More about loscosi's thyme

About Loscosi's Thyme

Thymus loscosii · also called Loscosi's thyme, Ebro thyme · herb

Thymus loscosii is a rare, tetraploid perennial sub-shrub endemic to the Ebro river basin in north-eastern Spain, where it grows on skeletal gypsiferous and loamy soils in a continental Mediterranean climate. It is listed in Spain's National Catalogue of Endangered Species and forms compact, sprawling mats with small pink-purple flowers in summer. As with all Thymus species, it demands full sun and perfect drainage — waterlogged or humid conditions are fatal. Thyme is non-toxic to cats, dogs, and horses according to the ASPCA.

Cold limit: USDA 6-9 · RHS H5 (-15 to 32°C)

Watch for — Fungal crown rot: Persistent wet conditions at the crown, especially in winter, cause rapid rotting. Plant in a raised bed or on a slight slope to ensure water drains away from the crown immediately.

What loscosi's thyme's hardiness rating actually means

Yes — loscosi's thyme 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. Loscosi's Thyme is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for loscosi's thyme 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 loscosi's thyme 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 loscosi's thyme can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Loscosi's Thyme hardiness — frequently asked questions

Is loscosi's thyme cold hardy?

Yes — loscosi's thyme 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. Loscosi's Thyme 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 loscosi's thyme can survive?

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

What hardiness zone is loscosi's thyme?

Loscosi's Thyme is rated USDA 6-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can loscosi's thyme 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 loscosi's thyme 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.