Cold hardiness & minimum temperature

Is Lydian Broom (Genista lydia)cold hardy? Hardiness zone & min temp

Also called Lydian broom, Lydia broom, Dwarf broom.

More about lydian broom

About Lydian Broom

Genista lydia · also called Lydian broom, Lydia broom · flowering

Genista lydia is a low, arching deciduous shrub native to rocky hillsides of eastern Europe and western Asia Minor, prized for its cascading sprays of bright yellow, pea-like flowers in late spring and early summer. It is extremely tough — tolerating drought, poor soil, coastal exposure, and salt — and holds an RHS Award of Garden Merit. The most important care point is never to prune into old wood, as brooms cannot regenerate from bare stems. It contains quinolizidine alkaloids (including cytisine) typical of the legume family, which are mildly toxic to cats and dogs if ingested in significant quantities.

Cold limit: USDA 5-9 · RHS H5 (-15 to 35°C)

What lydian broom's hardiness rating actually means

Yes — lydian broom is genuinely cold hardy. Rated RHS H5 and USDA 5-9, 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 — 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. Lydian Broom is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for lydian broom 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 lydian broom go outside or overwinter — and where?

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

Lydian Broom hardiness — frequently asked questions

Is lydian broom cold hardy?

Yes — lydian broom is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Lydian Broom is hardy across USDA 5-9; 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 lydian broom can survive?

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

What hardiness zone is lydian broom?

Lydian Broom is rated USDA 5-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can lydian broom survive winter outside?

Plant it out within USDA 5-9 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 lydian broom 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.