Cold hardiness & minimum temperature

Is Telephone Pea (Pisum sativum 'Alderman')cold hardy? Hardiness zone & min temp

Also called Alderman pea, Telephone pea, tall telephone.

More about telephone pea

About Telephone Pea

Pisum sativum 'Alderman' · also called Alderman pea, Telephone pea · edible

'Alderman', also sold as Telephone, is a tall heirloom shelling pea reaching 1.8-2.4 m and needing sturdy support. It yields long pods of large, sweet wrinkle-seeded peas over a long picking window. A cool-season legume, it fixes nitrogen, crops best in spring and autumn, and sulks in summer heat above 24°C.

Cold limit: USDA 3-11 as a cool-season annual (sown when soil reaches 7-10°C) · RHS H4 (young growth hardy to about -10°C; seedlings tolerate light frost) (13-18°C)

What telephone pea's hardiness rating actually means

Hardiness works differently for telephone pea: 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 H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 3-11 as a cool-season annual (sown when soil reaches 7-10°C) — 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 telephone pea 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 telephone pea 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 telephone pea 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 telephone pea

Telephone Pea 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.

Telephone Pea hardiness — frequently asked questions

Is telephone pea cold hardy?

Hardiness works differently for telephone pea: 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. Telephone Pea is grown 3-11 as a cool-season annual (sown when soil reaches 7-10°C); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature telephone pea 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 telephone pea?

Telephone Pea is rated USDA 3-11 as a cool-season annual (sown when soil reaches 7-10°C) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can telephone pea 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 telephone pea 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.