Cold hardiness & minimum temperature

Is Osteospermum 'Voltage Yellow' (Osteospermum ecklonis 'Voltage Yellow')cold hardy? Hardiness zone & min temp

Also called Voltage Yellow Cape Daisy, Yellow African Daisy.

More about osteospermum 'voltage yellow'

About Osteospermum 'Voltage Yellow'

Osteospermum ecklonis 'Voltage Yellow' · also called Voltage Yellow Cape Daisy, Yellow African Daisy · flowering

'Voltage Yellow' is a bright, early-flowering Cape daisy bearing golden-yellow rays around a dark eye on compact, weather-tolerant plants. Bred for daylength neutrality, it blooms reliably from spring through autumn in full sun without waiting on day length. A drought-tolerant tender perennial grown as an annual, it shines in containers and sunny bedding.

Cold limit: USDA 9-11 (grown as an annual in cooler zones) · RHS H3 (10-26°C)

What osteospermum 'voltage yellow''s hardiness rating actually means

Hardiness works differently for osteospermum 'voltage yellow': 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 H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 9-11 (grown as an annual in cooler zones) — 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 osteospermum 'voltage yellow' 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 osteospermum 'voltage yellow' 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 osteospermum 'voltage yellow' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline osteospermum 'voltage yellow'

Osteospermum 'Voltage Yellow' 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.

Osteospermum 'Voltage Yellow' hardiness — frequently asked questions

Is osteospermum 'voltage yellow' cold hardy?

Hardiness works differently for osteospermum 'voltage yellow': 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. Osteospermum 'Voltage Yellow' is grown 9-11 (grown as an annual in cooler zones); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature osteospermum 'voltage yellow' 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 osteospermum 'voltage yellow'?

Osteospermum 'Voltage Yellow' is rated USDA 9-11 (grown as an annual in cooler zones) and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can osteospermum 'voltage yellow' 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 osteospermum 'voltage yellow' 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.