Cold hardiness & minimum temperature

Is Pink Hyssop (Hyssopus officinalis 'Roseus')cold hardy? Hardiness zone & min temp

Also called Pink Hyssop, Rose-Pink Hyssop.

More about pink hyssop

About Pink Hyssop

Hyssopus officinalis 'Roseus' · also called Pink Hyssop, Rose-Pink Hyssop · herb

Pink Hyssop is a compact, semi-evergreen sub-shrub producing dense whorled spikes of rose-pink tubular flowers from July through September. Narrow dark green leaves are intensely aromatic with a bitter, camphorous scent. A superb pollinator plant for cottage gardens and formal herb knot gardens alike. Hardy to USDA zone 4, drought-tolerant, and excellent in alkaline chalk soils.

Cold limit: USDA 4–9 · RHS H7 (-15–30°C)

Watch for — Root rot in winter wet: Persistently wet winter soil is the primary cause of plant death. Ensure sharp drainage by planting in raised beds, on slopes, or with added grit. Gravel mulch around the crown helps deflect excess moisture. Avoid organic mulches that hold moisture against the stems.

What pink hyssop's hardiness rating actually means

Yes — pink hyssop is genuinely cold hardy. Rated RHS H7 and USDA 4–9, 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 4–9 — 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 below about −20 °C. Pink Hyssop is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for pink hyssop 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 pink hyssop go outside or overwinter — and where?

Plant it out within USDA 4–9 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 pink hyssop can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Pink Hyssop hardiness — frequently asked questions

Is pink hyssop cold hardy?

Yes — pink hyssop is genuinely cold hardy. Rated RHS H7 and USDA 4–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Pink Hyssop is hardy across USDA 4–9; 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 pink hyssop can survive?

Minimum survivable temperature is roughly below about −20 °C. Pink Hyssop is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is pink hyssop?

Pink Hyssop is rated USDA 4–9 and RHS H7 — Hardy in the severest European continental winters.

Can pink hyssop survive winter outside?

Plant it out within USDA 4–9 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 pink hyssop 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.