Cold hardiness & minimum temperature

Is Scaevola aemula 'Whirlwind White' (Scaevola aemula 'Whirlwind White')cold hardy? Hardiness zone & min temp

Also called Whirlwind White Fan Flower, White Trailing Scaevola.

More about scaevola aemula 'whirlwind white'

About Scaevola aemula 'Whirlwind White'

Scaevola aemula 'Whirlwind White' · also called Whirlwind White Fan Flower, White Trailing Scaevola · flowering

'Whirlwind White' is a vigorous trailing fan flower covered in crisp white, fan-shaped blooms all summer. An Australian-native warm-season annual, it is heat- and drought-tolerant, self-cleaning (no deadheading needed) and spreads enthusiastically, making it a standout spiller for hanging baskets, window boxes and large containers where it flowers from late spring to frost.

Cold limit: USDA 10-11 (perennial in frost-free zones; grown as an annual elsewhere) · RHS H2 (18-29°C)

Watch for — Frost kill: It dies back at frost where it cannot overwinter; grow as a tender annual outside frost-free climates.

What scaevola aemula 'whirlwind white''s hardiness rating actually means

Hardiness works differently for scaevola aemula 'whirlwind white': it is grown as a seasonal crop, not overwintered. The question is not "what zone" but "how long is your frost-free growing window". Its RHS rating of H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA 10-11 (perennial in frost-free zones; grown as an annual elsewhere) — 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

As an annual crop, its "minimum temperature" is the first hard frost — that is the end of the plant's life, not a survivable low. Many types are also damaged by light frost (around 0 °C).

Concretely, for scaevola aemula 'whirlwind white' as it gets too cold:

Light frost (around 0 to −2 °C) damages or kills tender summer crops outright; cold-hardy types take a few degrees of frost.
The plant does not "survive winter" — its life cycle simply ends, by design, when frost arrives or it finishes cropping.
A surprise late spring frost can also kill young transplants set out too early, before the season even starts.

Can scaevola aemula 'whirlwind white' go outside or overwinter — and where?

Time it to your frost dates: sow or plant out after the last spring frost, and aim to harvest before the first autumn frost.
In short-season zones, start it indoors or under cover to stretch the effective growing window.
Hardier crops in this group can be sown for an autumn or overwintered harvest in mild zones — check the specific crop.

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 scaevola aemula 'whirlwind white' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline scaevola aemula 'whirlwind white'

Scaevola aemula 'Whirlwind White' is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Use fleece, cloches or a cold frame at each end of the season to dodge a borderline frost and add growing weeks.
Have row cover ready for an unexpected late spring or early autumn frost.
Know your local last- and first-frost dates and count back the crop’s days-to-maturity to schedule the sowing.

Scaevola aemula 'Whirlwind White' hardiness — frequently asked questions

Is scaevola aemula 'whirlwind white' cold hardy?

Hardiness works differently for scaevola aemula 'whirlwind white': it is grown as a seasonal crop, not overwintered. The question is not "what zone" but "how long is your frost-free growing window". A seasonal crop, not a perennial. Scaevola aemula 'Whirlwind White' is grown 10-11 (perennial in frost-free zones; grown as an annual elsewhere); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature scaevola aemula 'whirlwind white' can survive?

As an annual crop, its "minimum temperature" is the first hard frost — that is the end of the plant's life, not a survivable low. Many types are also damaged by light frost (around 0 °C).

What hardiness zone is scaevola aemula 'whirlwind white'?

Scaevola aemula 'Whirlwind White' is rated USDA 10-11 (perennial in frost-free zones; grown as an annual elsewhere) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can scaevola aemula 'whirlwind white' survive winter outside?

Time it to your frost dates: sow or plant out after the last spring frost, and aim to harvest before the first autumn frost. In short-season zones, start it indoors or under cover to stretch the effective growing window. Hardier crops in this group can be sown for an autumn or overwintered harvest in mild zones — check the specific crop.

How do I protect scaevola aemula 'whirlwind white' from frost?

Use fleece, cloches or a cold frame at each end of the season to dodge a borderline frost and add growing weeks. Have row cover ready for an unexpected late spring or early autumn frost. Know your local last- and first-frost dates and count back the crop’s days-to-maturity to schedule the sowing.