Cold hardiness & minimum temperature

Is Purple-Top Germander (Teucrium hircanicum)cold hardy? Hardiness zone & min temp

Also called Purple-top germander, Caucasian germander, Iranian germander.

More about purple-top germander

About Purple-Top Germander

Teucrium hircanicum · also called Purple-top germander, Caucasian germander · flowering

Teucrium hircanicum is a vigorous, clump-forming herbaceous to semi-evergreen perennial native to the Caucasus region, northern Iran (Hyrcania), and adjacent Turkey, where it grows in open woodland margins, rocky slopes, and disturbed ground. It produces tall, showy spikes of rich burgundy-purple flowers over a very long season from midsummer through autumn, making it one of the most garden-worthy Teucrium species. It is more tolerant of moisture and shade than most Mediterranean relatives, though it still dislikes waterlogging. Treat as mildly toxic to pets in line with the Teucrium genus.

Cold limit: USDA 5-9 · RHS H6 (-15 to 30°C)

What purple-top germander's hardiness rating actually means

Yes — purple-top germander is genuinely cold hardy. Rated RHS H6 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 5-9 — 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 −20 to −15 °C. Purple-Top Germander is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for purple-top germander as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 purple-top germander go outside or overwinter — and where?

Plant it out within USDA 5-9 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 purple-top germander can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Purple-Top Germander hardiness — frequently asked questions

Is purple-top germander cold hardy?

Yes — purple-top germander is genuinely cold hardy. Rated RHS H6 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Purple-Top Germander is hardy across USDA 5-9; 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 purple-top germander can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Purple-Top Germander is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is purple-top germander?

Purple-Top Germander is rated USDA 5-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can purple-top germander survive winter outside?

Plant it out within USDA 5-9 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 purple-top germander below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.