Cold hardiness & minimum temperature

Is Aquadulce Broad Bean (Vicia faba)cold hardy? Hardiness zone & min temp

Also called Fava Bean, Field Bean, Windsor Bean.

More about aquadulce broad bean

About Aquadulce Broad Bean

Vicia faba · also called Fava Bean, Field Bean · edible

Aquadulce is the premier autumn-sowing broad bean variety, producing long, robust pods with large, sweet beans. Exceptionally winter-hardy, it is sown in late autumn in the UK for an early summer harvest. Causes 'favism' in genetically susceptible people. ASPCA does not list Vicia faba as toxic to cats and dogs.

Cold limit: USDA 3-9 (cool-season annual; sown autumn or early spring) · RHS H5 (5-22°C)

What aquadulce broad bean's hardiness rating actually means

Hardiness works differently for aquadulce broad bean: 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 H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 3-9 (cool-season annual; sown autumn or early spring) — 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 aquadulce broad bean 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 aquadulce broad bean 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 aquadulce broad bean can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Frost protection for borderline aquadulce broad bean

Aquadulce Broad Bean 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.

Aquadulce Broad Bean hardiness — frequently asked questions

Is aquadulce broad bean cold hardy?

Hardiness works differently for aquadulce broad bean: 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. Aquadulce Broad Bean is grown 3-9 (cool-season annual; sown autumn or early spring); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature aquadulce broad bean 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 aquadulce broad bean?

Aquadulce Broad Bean is rated USDA 3-9 (cool-season annual; sown autumn or early spring) and RHS H5 — Hardy in most of the UK and in cold winters.

Can aquadulce broad bean 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 aquadulce broad bean 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.