Cold hardiness & minimum temperature

Is Oleander (Nerium oleander)cold hardy? Hardiness zone & min temp

Also called Oleander, Rose Bay.

More about oleander

About Oleander

Nerium oleander · also called Oleander, Rose Bay · flowering

Oleander is a drought-tolerant evergreen shrub from the Mediterranean, prized for clusters of pink, white or red flowers all summer. It thrives in full sun and lean, fast-draining soil, shrugging off heat and salt spray. Every part is intensely poisonous to people and pets, so site it well away from animals and children.

Cold limit: USDA 8-11 (overwinter under glass in colder zones) · RHS H4 (10-30°C)

Watch for — Frost damage: Stems and foliage are scorched below about -5°C. Mulch the crown, grow in a sheltered spot, or move containers under cover for winter in cold regions.

What oleander's hardiness rating actually means

Yes — oleander is genuinely cold hardy. Rated RHS H4 and USDA 8-11 (overwinter under glass in colder zones), 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 8-11 (overwinter under glass in colder 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 −10 to −5 °C. Oleander is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for oleander 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 oleander go outside or overwinter — and where?

Plant it out within USDA 8-11 (overwinter under glass in colder 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 oleander can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Oleander hardiness — frequently asked questions

Is oleander cold hardy?

Yes — oleander is genuinely cold hardy. Rated RHS H4 and USDA 8-11 (overwinter under glass in colder zones), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Oleander is hardy across USDA 8-11 (overwinter under glass in colder 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 oleander can survive?

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

What hardiness zone is oleander?

Oleander is rated USDA 8-11 (overwinter under glass in colder zones) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can oleander survive winter outside?

Plant it out within USDA 8-11 (overwinter under glass in colder 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 oleander 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.