Cold hardiness & minimum temperature

Is Lemon Thyme (Thymus citriodorus)cold hardy? Hardiness zone & min temp

Also called Citrus Thyme.

More about lemon thyme

About Lemon Thyme

Thymus citriodorus · also called Citrus Thyme · herb

Lemon Thyme is a low, woody Mediterranean herb with small evergreen leaves carrying a bright lemon-thyme scent, excellent for poultry, fish and roasted vegetables. A hardy, drought-tolerant subshrub, it craves full sun and sharp drainage and resents wet feet. Light trimming keeps it compact, and it doubles as a fragrant edging or container plant.

Cold limit: USDA 5-9 · RHS H4 (10-26°C)

Watch for — Winter dieback in wet soil: Cold combined with wet roots kills it faster than cold alone. Ensure excellent drainage and grow in pots that can be moved to shelter in harsh winters.

What lemon thyme's hardiness rating actually means

Yes — lemon thyme is genuinely cold hardy. Rated RHS H4 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. 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 −10 to −5 °C. Lemon Thyme is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for lemon thyme as it gets too cold:

It tolerates winter lows to about −10 to −5 °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 lemon thyme 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 lemon thyme can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Lemon Thyme hardiness — frequently asked questions

Is lemon thyme cold hardy?

Yes — lemon thyme is genuinely cold hardy. Rated RHS H4 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Lemon Thyme 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 lemon thyme can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Lemon Thyme is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is lemon thyme?

Lemon Thyme is rated USDA 5-9 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can lemon thyme 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 lemon thyme below its minimum temperature?

It tolerates winter lows to about −10 to −5 °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.