Cold hardiness & minimum temperature

Is Syrian Oregano (Origanum syriacum)cold hardy? Hardiness zone & min temp

Also called Syrian Oregano, Za'atar, Bible Hyssop.

More about syrian oregano

About Syrian Oregano

Origanum syriacum · also called Syrian Oregano, Za'atar · herb

Syrian Oregano is the wild Middle Eastern herb at the heart of the za'atar spice blend, with grey-green woolly leaves and a warm, savoury oregano-thyme-marjoram flavour. A tender Mediterranean perennial, it demands full sun and sharp-draining, lean soil, tolerates drought, and resents cold, wet winters.

Cold limit: USDA 7-11 (tender perennial; overwinter under cover in cold regions) · RHS H3 (16-30°C)

Watch for — Winter wet rot: The biggest killer in cool climates. Provide sharp drainage, grow in pots, and move under cover for cold, wet winters.

What syrian oregano's hardiness rating actually means

Syrian Oregano is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 7-11 (tender perennial; overwinter under cover in cold regions) — 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 −5 to 1 °C — a light, short frost only. Syrian Oregano shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for syrian oregano as it gets too cold:

Down to roughly about −5 to 1 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can syrian oregano go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 7-11 (tender perennial; overwinter under cover in cold regions) or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 syrian oregano can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline syrian oregano

Syrian Oregano is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Syrian Oregano hardiness — frequently asked questions

Is syrian oregano cold hardy?

Syrian Oregano is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 7-11 (tender perennial; overwinter under cover in cold regions) (and sheltered UK gardens) syrian oregano can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature syrian oregano can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Syrian Oregano shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is syrian oregano?

Syrian Oregano is rated USDA 7-11 (tender perennial; overwinter under cover in cold regions) and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can syrian oregano survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 7-11 (tender perennial; overwinter under cover in cold regions) or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect syrian oregano from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.