Cold hardiness & minimum temperature

Is Parsley (Petroselinum crispum)cold hardy? Hardiness zone & min temp

Also called flat-leaf parsley, Italian parsley, curly parsley.

About Parsley

Petroselinum crispum · also called flat-leaf parsley, Italian parsley · herb

Parsley is a biennial herb usually grown as an annual for its flavourful leaves. It is slow to germinate but otherwise undemanding, thriving in moisture-retentive soil with regular harvesting. Mildly toxic to birds and some grazing pets in large amounts.

Petroselinum crispum is a Mediterranean-native biennial in the carrot family, typically grown as an annual in cold-winter regions.

Notoriously slow to germinate (about 2-5 weeks); soaking seed 24 hours in warm water speeds sprouting. First-year rosette grows 12-18 in before second-year flowering.

Cold limit: USDA 4-9 (biennial) · RHS H4 (10-24°C)

Sources: extension.umn.edu, hort.extension.wisc.edu, plants.ces.ncsu.edu

What parsley's hardiness rating actually means

Yes — parsley is genuinely cold hardy. Rated RHS H4 and USDA 4-9 (biennial), it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 4-9 (biennial) — 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 −10 to −5 °C. Parsley is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for parsley as it gets too cold:

It tolerates winter lows to about −10 to −5 °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 parsley go outside or overwinter — and where?

Plant it out within USDA 4-9 (biennial) 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 parsley can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Parsley hardiness — frequently asked questions

Is parsley cold hardy?

Yes — parsley is genuinely cold hardy. Rated RHS H4 and USDA 4-9 (biennial), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Parsley is hardy across USDA 4-9 (biennial); 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 parsley can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Parsley is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is parsley?

Parsley is rated USDA 4-9 (biennial) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can parsley survive winter outside?

Plant it out within USDA 4-9 (biennial) 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 parsley below its minimum temperature?

It tolerates winter lows to about −10 to −5 °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.