Cold hardiness & minimum temperature

Is Nepeta 'Six Hills Giant' (Nepeta 'Six Hills Giant')cold hardy? Hardiness zone & min temp

Also called Six Hills Giant catmint, tall catmint.

More about nepeta 'six hills giant'

About Nepeta 'Six Hills Giant'

Nepeta 'Six Hills Giant' · also called Six Hills Giant catmint, tall catmint · flowering

Nepeta 'Six Hills Giant' is a large, vigorous catmint forming billowing mounds of grey-green aromatic foliage smothered in long spikes of lavender-blue flowers from early summer. Exceptionally bee-friendly, drought-tolerant and easy, it is a classic for softening path edges and rose borders. A hard cut-back after the first flush triggers a strong second bloom into autumn.

Cold limit: USDA 4-8 · RHS H7 (-29 to 30°C)

Watch for — Crown rot in wet soil: Heavy, wet ground rots the crown, especially in winter. Plant in sharply drained soil and add grit to clay.

What nepeta 'six hills giant''s hardiness rating actually means

Yes — nepeta 'six hills giant' is genuinely cold hardy. Rated RHS H7 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 4-8 — 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 below about −20 °C. Nepeta 'Six Hills Giant' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for nepeta 'six hills giant' as it gets too cold:

It tolerates winter lows to about −20 °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 nepeta 'six hills giant' go outside or overwinter — and where?

Plant it out within USDA 4-8 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 nepeta 'six hills giant' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Nepeta 'Six Hills Giant' hardiness — frequently asked questions

Is nepeta 'six hills giant' cold hardy?

Yes — nepeta 'six hills giant' is genuinely cold hardy. Rated RHS H7 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Nepeta 'Six Hills Giant' is hardy across USDA 4-8; 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 nepeta 'six hills giant' can survive?

Minimum survivable temperature is roughly below about −20 °C. Nepeta 'Six Hills Giant' is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is nepeta 'six hills giant'?

Nepeta 'Six Hills Giant' is rated USDA 4-8 and RHS H7 — Hardy in the severest European continental winters.

Can nepeta 'six hills giant' survive winter outside?

Plant it out within USDA 4-8 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 nepeta 'six hills giant' below its minimum temperature?

It tolerates winter lows to about −20 °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.