Cold hardiness & minimum temperature

Is Cole's Prostrate Hemlock (Tsuga canadensis 'Cole's Prostrate')cold hardy? Hardiness zone & min temp

Also called Cole's Prostrate Hemlock, Cole's Prostrate Eastern Hemlock.

More about cole's prostrate hemlock

About Cole's Prostrate Hemlock

Tsuga canadensis 'Cole's Prostrate' · also called Cole's Prostrate Hemlock, Cole's Prostrate Eastern Hemlock · flowering

Cole's Prostrate Hemlock is an ultra-dwarf, ground-hugging cultivar of Eastern Hemlock that spreads horizontally with almost no vertical growth. Its flat, layered branches clothed in tiny dark-green needles with silver undersides create a carpet-like effect ideal for rockeries, slopes, and specimen planting. Exceptionally shade-tolerant and very slow-growing.

Cold limit: USDA 3-7 · RHS H7 (-35 to 22°C)

What cole's prostrate hemlock's hardiness rating actually means

Yes — cole's prostrate hemlock is genuinely cold hardy. Rated RHS H7 and USDA 3-7, 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 3-7 — 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. Cole's Prostrate Hemlock is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for cole's prostrate hemlock 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 cole's prostrate hemlock go outside or overwinter — and where?

Plant it out within USDA 3-7 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 cole's prostrate hemlock can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Cole's Prostrate Hemlock hardiness — frequently asked questions

Is cole's prostrate hemlock cold hardy?

Yes — cole's prostrate hemlock is genuinely cold hardy. Rated RHS H7 and USDA 3-7, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Cole's Prostrate Hemlock is hardy across USDA 3-7; 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 cole's prostrate hemlock can survive?

Minimum survivable temperature is roughly below about −20 °C. Cole's Prostrate Hemlock is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is cole's prostrate hemlock?

Cole's Prostrate Hemlock is rated USDA 3-7 and RHS H7 — Hardy in the severest European continental winters.

Can cole's prostrate hemlock survive winter outside?

Plant it out within USDA 3-7 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 cole's prostrate hemlock 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.