Cold hardiness & minimum temperature

Is Flat-Leaf Parsley (Petroselinum crispum var. neapolitanum)cold hardy? Hardiness zone & min temp

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

More about flat-leaf parsley

About Flat-Leaf Parsley

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

Flat-leaf parsley is a hardy biennial grown as a culinary annual for its flat, deeply cut leaves with a cleaner, stronger flavor than curly types. It thrives in full sun to part shade, moist fertile soil, and steady moisture. Slow to germinate but productive once established, it bolts in its second year.

Cold limit: USDA 5-9 (grown as annual; overwinters in milder zones) · RHS H5 (7-24°C)

What flat-leaf parsley's hardiness rating actually means

Yes — flat-leaf parsley is genuinely cold hardy. Rated RHS H5 and USDA 5-9 (grown as annual; overwinters in milder zones), 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 (grown as annual; overwinters in milder zones) — 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. Flat-Leaf Parsley is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for flat-leaf parsley 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 flat-leaf parsley go outside or overwinter — and where?

Plant it out within USDA 5-9 (grown as annual; overwinters in milder zones) 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 flat-leaf parsley can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Flat-Leaf Parsley hardiness — frequently asked questions

Is flat-leaf parsley cold hardy?

Yes — flat-leaf parsley is genuinely cold hardy. Rated RHS H5 and USDA 5-9 (grown as annual; overwinters in milder zones), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Flat-Leaf Parsley is hardy across USDA 5-9 (grown as annual; overwinters in milder zones); 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 flat-leaf parsley can survive?

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

What hardiness zone is flat-leaf parsley?

Flat-Leaf Parsley is rated USDA 5-9 (grown as annual; overwinters in milder zones) and RHS H5 — Hardy in most of the UK and in cold winters.

Can flat-leaf parsley survive winter outside?

Plant it out within USDA 5-9 (grown as annual; overwinters in milder zones) 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 flat-leaf parsley 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.