Cold hardiness & minimum temperature

Is Calypso Cilantro (Coriandrum sativum 'Calypso')cold hardy? Hardiness zone & min temp

Also called Calypso Cilantro, Coriander, Chinese Parsley.

More about calypso cilantro

About Calypso Cilantro

Coriandrum sativum 'Calypso' · also called Calypso Cilantro, Coriander · herb

A PBR-protected slow-bolting cilantro variety bred specifically for maximum leaf production, reportedly 3 weeks slower to bolt than the benchmark 'Santo'. Features deep green, broad, bushy foliage with an upright, lush habit. Excellent for market growers and home gardeners seeking extended fresh harvests.

Cold limit: USDA 2-11 (grown as annual) · RHS H2 (10–28°C)

Watch for — Bolting in heat: Even with its enhanced bolt resistance, 'Calypso' will run to seed in sustained temperatures above 28°C. Use shade cloth, succession-sow, and mulch roots to keep soil cool.

What calypso cilantro's hardiness rating actually means

Calypso Cilantro is half-hardy (RHS H2). 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 H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA 2-11 (grown as annual) — 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 1 to 5 °C — tolerates cold but no real frost. Calypso Cilantro shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for calypso cilantro as it gets too cold:

Down to roughly about 1 to 5 °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 calypso cilantro go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 2-11 (grown as annual) 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 calypso cilantro can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline calypso cilantro

Calypso Cilantro 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.

Calypso Cilantro hardiness — frequently asked questions

Is calypso cilantro cold hardy?

Calypso Cilantro is half-hardy (RHS H2). 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 2-11 (grown as annual) (and sheltered UK gardens) calypso cilantro can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature calypso cilantro can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Calypso Cilantro shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is calypso cilantro?

Calypso Cilantro is rated USDA 2-11 (grown as annual) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can calypso cilantro survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 2-11 (grown as annual) 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 calypso cilantro 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.