Cold hardiness & minimum temperature

Is Indigo Gem Honeyberry (Lonicera caerulea 'Indigo Gem')cold hardy? Hardiness zone & min temp

Also called Indigo Gem honeyberry.

More about indigo gem honeyberry

About Indigo Gem Honeyberry

Lonicera caerulea 'Indigo Gem' · also called Indigo Gem honeyberry · edible

'Indigo Gem' is a University of Saskatchewan haskap of the Indigo series, noted for heavy yields of oval blue berries with a flavour reminiscent of blueberry crossed with raspberry, excellent for processing into jam and baked goods. Very cold-hardy and vigorous, it requires a compatible pollinating variety such as 'Honey Bee' or 'Aurora' to crop well.

Cold limit: USDA 2-7 · RHS H7 (-45 to 30°C)

What indigo gem honeyberry's hardiness rating actually means

Yes — indigo gem honeyberry is genuinely cold hardy. Rated RHS H7 and USDA 2-7, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 2-7 — 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 below about −20 °C. Indigo Gem Honeyberry is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for indigo gem honeyberry as it gets too cold:

It tolerates winter lows to about −20 °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 indigo gem honeyberry go outside or overwinter — and where?

Plant it out within USDA 2-7 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 indigo gem honeyberry can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Indigo Gem Honeyberry hardiness — frequently asked questions

Is indigo gem honeyberry cold hardy?

Yes — indigo gem honeyberry is genuinely cold hardy. Rated RHS H7 and USDA 2-7, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Indigo Gem Honeyberry is hardy across USDA 2-7; 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 indigo gem honeyberry can survive?

Minimum survivable temperature is roughly below about −20 °C. Indigo Gem Honeyberry is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is indigo gem honeyberry?

Indigo Gem Honeyberry is rated USDA 2-7 and RHS H7 — Hardy in the severest European continental winters.

Can indigo gem honeyberry survive winter outside?

Plant it out within USDA 2-7 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 indigo gem honeyberry below its minimum temperature?

It tolerates winter lows to about −20 °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.