Cold hardiness & minimum temperature

Is Pecan 'Sumner' (Carya illinoinensis 'Sumner')cold hardy? Hardiness zone & min temp

Also called Sumner pecan.

More about pecan 'sumner'

About Pecan 'Sumner'

Carya illinoinensis 'Sumner' · also called Sumner pecan · edible

'Sumner' is a productive, late-season pecan with good scab tolerance and consistent, well-filled medium-large nuts, making it a dependable orchard cultivar in the Southeast. A Type II (protogynous) cultivar, it sets best with an overlapping protandrous pollinator. Its disease tolerance and steady yields suit humid growing regions.

Cold limit: USDA 6-9 (late ripening needs a long season) · RHS H5 (-15 to 38°C)

What pecan 'sumner''s hardiness rating actually means

Yes — pecan 'sumner' is genuinely cold hardy. Rated RHS H5 and USDA 6-9 (late ripening needs a long season), 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 6-9 (late ripening needs a long season) — 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. Pecan 'Sumner' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for pecan 'sumner' 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 pecan 'sumner' go outside or overwinter — and where?

Plant it out within USDA 6-9 (late ripening needs a long season) 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 pecan 'sumner' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Pecan 'Sumner' hardiness — frequently asked questions

Is pecan 'sumner' cold hardy?

Yes — pecan 'sumner' is genuinely cold hardy. Rated RHS H5 and USDA 6-9 (late ripening needs a long season), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Pecan 'Sumner' is hardy across USDA 6-9 (late ripening needs a long season); 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 pecan 'sumner' can survive?

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

What hardiness zone is pecan 'sumner'?

Pecan 'Sumner' is rated USDA 6-9 (late ripening needs a long season) and RHS H5 — Hardy in most of the UK and in cold winters.

Can pecan 'sumner' survive winter outside?

Plant it out within USDA 6-9 (late ripening needs a long season) 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 pecan 'sumner' 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.