Cold hardiness & minimum temperature

Is Katz Sakura stock (Matthiola incana 'Katz Sakura')cold hardy? Hardiness zone & min temp

Also called Katz Sakura stock, Stock, Gillyflower, Brompton stock.

More about katz sakura stock

About Katz Sakura stock

Matthiola incana 'Katz Sakura' · also called Katz Sakura stock, Stock · flowering

Katz Sakura is a cherry-blossom-pink cultivar in the early-flowering Katz series of Matthiola incana, bred specifically for the cut-flower trade. Dense double-flowered spikes carry an intense clove-like fragrance. A cool-season crop that peaks in late spring; struggles in summer heat above 27°C. Excellent vase life of 7–10 days.

Cold limit: USDA 7-10 · RHS H4 (7–18°C)

Watch for — Heat-induced bolting: Temperatures above 27°C cause premature bolting, short spikes, and flower blast. Time planting for autumn or early spring in warm climates; in cool temperate regions, plant in early spring for late-spring harvest.

What katz sakura stock's hardiness rating actually means

Yes — katz sakura stock is genuinely cold hardy. Rated RHS H4 and USDA 7-10, 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 7-10 — 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 −10 to −5 °C. Katz Sakura stock is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for katz sakura stock 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 katz sakura stock go outside or overwinter — and where?

Plant it out within USDA 7-10 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 katz sakura stock can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Frost protection for borderline katz sakura stock

Katz Sakura stock is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

At the cold edge of its range, mulch the root zone in late autumn to buffer the deepest freezes.
Protect container specimens — pots freeze through far faster than open ground, costing roughly a zone of hardiness.
Shelter new growth from late spring frosts with fleece if a hard night is forecast.

Katz Sakura stock hardiness — frequently asked questions

Is katz sakura stock cold hardy?

Yes — katz sakura stock is genuinely cold hardy. Rated RHS H4 and USDA 7-10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Katz Sakura stock is hardy across USDA 7-10; 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 katz sakura stock can survive?

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

What hardiness zone is katz sakura stock?

Katz Sakura stock is rated USDA 7-10 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can katz sakura stock survive winter outside?

Plant it out within USDA 7-10 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.

How do I protect katz sakura stock from frost?

At the cold edge of its range, mulch the root zone in late autumn to buffer the deepest freezes. Protect container specimens — pots freeze through far faster than open ground, costing roughly a zone of hardiness. Shelter new growth from late spring frosts with fleece if a hard night is forecast.