Cold hardiness & minimum temperature

Is All Blue Potato (Solanum tuberosum 'All Blue')cold hardy? Hardiness zone & min temp

Also called All Blue potato, blue potato, purple-blue potato.

More about all blue potato

About All Blue Potato

Solanum tuberosum 'All Blue' · also called All Blue potato, blue potato · edible

'All Blue' is a maincrop heirloom potato with deep blue-purple skin and dense violet flesh that holds its colour when cooked, thanks to high anthocyanin content. It is grown for boiling, roasting and vivid mash. Plant seed tubers in spring, hill the stems, and harvest tubers once the foliage yellows and dies back.

Cold limit: USDA Grown as a warm-season annual; plant after frost in zones 3-10 · RHS H2 (15-20°C)

What all blue potato's hardiness rating actually means

Hardiness works differently for all blue potato: 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 Grown as a warm-season annual; plant after frost in zones 3-10 — 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

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 all blue potato 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 all blue potato 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 all blue potato 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 all blue potato

All Blue Potato 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.

All Blue Potato hardiness — frequently asked questions

Is all blue potato cold hardy?

Hardiness works differently for all blue potato: 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. All Blue Potato is grown Grown as a warm-season annual; plant after frost in zones 3-10; you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature all blue potato 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 all blue potato?

All Blue Potato is rated USDA Grown as a warm-season annual; plant after frost in zones 3-10 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can all blue potato 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 all blue potato 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.