Cold hardiness & minimum temperature

Is Issai Kiwi (Actinidia arguta 'Issai')cold hardy? Hardiness zone & min temp

Also called Issai kiwi, self-fertile hardy kiwi.

More about issai kiwi

About Issai Kiwi

Actinidia arguta 'Issai' · also called Issai kiwi, self-fertile hardy kiwi · edible

'Issai' is a self-fertile hardy kiwi that fruits without a separate male pollinator, making it ideal for small gardens. It bears smooth-skinned, grape-sized kiwi berries on a vigorous deciduous vine and can crop young. Less rampant than the species, it still needs sturdy support, full sun, and free-draining soil to ripen well.

Cold limit: USDA 5-9 (outdoor) · RHS H5 (-25 to 30°C)

Watch for — Frost damage to new growth: Spring shoots and flowers are frost-tender and easily lost to a late freeze. Site in a sheltered sunny spot and protect early growth when frost is forecast.

What issai kiwi's hardiness rating actually means

Yes — issai kiwi is genuinely cold hardy. Rated RHS H5 and USDA 5-9 (outdoor), 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 (outdoor) — 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. Issai Kiwi is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for issai kiwi 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 issai kiwi go outside or overwinter — and where?

Plant it out within USDA 5-9 (outdoor) 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 issai kiwi can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Issai Kiwi hardiness — frequently asked questions

Is issai kiwi cold hardy?

Yes — issai kiwi is genuinely cold hardy. Rated RHS H5 and USDA 5-9 (outdoor), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Issai Kiwi is hardy across USDA 5-9 (outdoor); 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 issai kiwi can survive?

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

What hardiness zone is issai kiwi?

Issai Kiwi is rated USDA 5-9 (outdoor) and RHS H5 — Hardy in most of the UK and in cold winters.

Can issai kiwi survive winter outside?

Plant it out within USDA 5-9 (outdoor) 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 issai kiwi 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.