Cold hardiness & minimum temperature

Is Winter Marjoram (Origanum heracleoticum)cold hardy? Hardiness zone & min temp

Also called Winter Marjoram, Greek Oregano, Italian Oregano, White Oregano.

More about winter marjoram

About Winter Marjoram

Origanum heracleoticum · also called Winter Marjoram, Greek Oregano · herb

Winter Marjoram is a pungently aromatic perennial herb from the eastern Mediterranean, often sold as Greek or Italian oregano. Its small, woolly white leaves carry the intense flavour beloved in Italian and Greek cuisines. Exceptionally drought-tolerant, it requires full sun, lean well-drained soil, and minimal watering to produce its most flavoursome leaves.

Cold limit: USDA 5-9 · RHS H5 (15–30°C)

What winter marjoram's hardiness rating actually means

Yes — winter marjoram is genuinely cold hardy. Rated RHS H5 and USDA 5-9, 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 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 −15 to −10 °C. Winter Marjoram is built for winter — once established it takes hard frost and snow in its stride.

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

Winter Marjoram hardiness — frequently asked questions

Is winter marjoram cold hardy?

Yes — winter marjoram is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Winter Marjoram 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 winter marjoram can survive?

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

What hardiness zone is winter marjoram?

Winter Marjoram is rated USDA 5-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can winter marjoram 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 winter marjoram 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.