Cold hardiness & minimum temperature

Is Silver Queen Thyme (Thymus x citriodorus 'Silver Queen')cold hardy? Hardiness zone & min temp

Also called Silver Queen thyme, silver lemon thyme.

More about silver queen thyme

About Silver Queen Thyme

Thymus x citriodorus 'Silver Queen' · also called Silver Queen thyme, silver lemon thyme · herb

Silver Queen is a lemon-scented thyme with small grey-green leaves edged in creamy white, forming a low, spreading evergreen mound. Both culinary and ornamental, it carries pale pink-mauve summer flowers loved by bees. This sun-loving, drought-hardy Mediterranean herb thrives in poor, sharply drained soil and is ideal for edging, herb beds and gravel gardens.

Cold limit: USDA 5-9 (hardy evergreen perennial outdoors) · RHS H4 (15-27°C)

Watch for — Root rot from overwatering: Blackening, dieback and collapse in wet or heavy soil. Provide sharp drainage, water sparingly, and avoid sitting in winter wet.

What silver queen thyme's hardiness rating actually means

Yes — silver queen thyme is genuinely cold hardy. Rated RHS H4 and USDA 5-9 (hardy evergreen perennial outdoors), 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 (hardy evergreen perennial outdoors) — 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. Silver Queen Thyme is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for silver queen 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 silver queen thyme go outside or overwinter — and where?

Plant it out within USDA 5-9 (hardy evergreen perennial outdoors) 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 silver queen thyme can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Silver Queen Thyme hardiness — frequently asked questions

Is silver queen thyme cold hardy?

Yes — silver queen thyme is genuinely cold hardy. Rated RHS H4 and USDA 5-9 (hardy evergreen perennial outdoors), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Silver Queen Thyme is hardy across USDA 5-9 (hardy evergreen perennial outdoors); 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 silver queen thyme can survive?

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

What hardiness zone is silver queen thyme?

Silver Queen Thyme is rated USDA 5-9 (hardy evergreen perennial outdoors) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can silver queen thyme survive winter outside?

Plant it out within USDA 5-9 (hardy evergreen perennial outdoors) 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 silver queen 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.