Cold hardiness & minimum temperature

Is Night-scented stock (Matthiola longipetala)cold hardy? Hardiness zone & min temp

Also called Night-scented stock, Evening stock, Perfume plant, Gilly flower.

More about night-scented stock

About Night-scented stock

Matthiola longipetala · also called Night-scented stock, Evening stock · flowering

Night-scented stock is a fast-growing hardy annual whose small, purple or pale lilac flowers appear modest by day — petals fold inward in sunlight — but open wide at dusk, releasing an extraordinarily powerful, sweet fragrance. Sow directly into beds in full sun, water sparingly, and expect flowers within 6–8 weeks from seed.

Cold limit: USDA Annual; sow in zones 2–10 · RHS H5 (5–22°C)

What night-scented stock's hardiness rating actually means

Yes — night-scented stock is genuinely cold hardy. Rated RHS H5 and USDA Annual; sow in zones 2–10, 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 Annual; sow in zones 2–10 — 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. Night-scented stock is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for night-scented stock 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 night-scented stock go outside or overwinter — and where?

Plant it out within USDA Annual; sow in zones 2–10 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 night-scented stock can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Night-scented stock hardiness — frequently asked questions

Is night-scented stock cold hardy?

Yes — night-scented stock is genuinely cold hardy. Rated RHS H5 and USDA Annual; sow in zones 2–10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Night-scented stock is hardy across USDA Annual; sow in zones 2–10; 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 night-scented stock can survive?

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

What hardiness zone is night-scented stock?

Night-scented stock is rated USDA Annual; sow in zones 2–10 and RHS H5 — Hardy in most of the UK and in cold winters.

Can night-scented stock survive winter outside?

Plant it out within USDA Annual; sow in zones 2–10 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 night-scented stock 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.