Cold hardiness & minimum temperature

Is Two-Flowered Everlasting Pea (Lathyrus grandiflorus)cold hardy? Hardiness zone & min temp

Also called Two-Flowered Everlasting Pea, Everlasting Pea, Perennial Sweet Pea.

More about two-flowered everlasting pea

About Two-Flowered Everlasting Pea

Lathyrus grandiflorus · also called Two-Flowered Everlasting Pea, Everlasting Pea · flowering

A vigorous, tuberous-rooted perennial climbing pea from the Mediterranean, bearing pairs of large, vivid cerise-pink flowers from early summer to early autumn. Unlike annual sweet peas, it spreads by underground rhizomes and returns reliably each year. Fully hardy to H6, it suits cottage gardens, sunny fences, and informal hedges, with minimal care once established.

Cold limit: USDA 5–9 · RHS H6 (-20–25°C)

What two-flowered everlasting pea's hardiness rating actually means

Yes — two-flowered everlasting pea is genuinely cold hardy. Rated RHS H6 and USDA 5–9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. 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 −20 to −15 °C. Two-Flowered Everlasting Pea is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for two-flowered everlasting pea as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 two-flowered everlasting pea 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 two-flowered everlasting pea can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Two-Flowered Everlasting Pea hardiness — frequently asked questions

Is two-flowered everlasting pea cold hardy?

Yes — two-flowered everlasting pea is genuinely cold hardy. Rated RHS H6 and USDA 5–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Two-Flowered Everlasting Pea 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 two-flowered everlasting pea can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Two-Flowered Everlasting Pea is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is two-flowered everlasting pea?

Two-Flowered Everlasting Pea is rated USDA 5–9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can two-flowered everlasting pea 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 two-flowered everlasting pea below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.