Cold hardiness & minimum temperature

Is Aunt Ruby's German Green Tomato (Solanum lycopersicum "Aunt Ruby's German Green")cold hardy? Hardiness zone & min temp

Also called Aunt Ruby's German Green tomato, green beefsteak tomato.

More about aunt ruby's german green tomato

About Aunt Ruby's German Green Tomato

Solanum lycopersicum "Aunt Ruby's German Green" · also called Aunt Ruby's German Green tomato, green beefsteak tomato · edible

Aunt Ruby's German Green is a large indeterminate heirloom beefsteak that ripens green-gold with a sweet, spicy-tart flavour. Fruit reach 280-450 g on vigorous vines needing strong staking. As a warm-season annual it demands full sun, steady deep watering and a long 75-85 day season to colour and soften before frost.

Cold limit: USDA Grown as a warm-season annual in all zones; transplant after last frost · RHS H2 (18-29°C)

What aunt ruby's german green tomato's hardiness rating actually means

Aunt Ruby's German Green Tomato is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. 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 in all zones; transplant after last frost — 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

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Aunt Ruby's German Green Tomato shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for aunt ruby's german green tomato as it gets too cold:

Down to roughly about 1 to 5 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can aunt ruby's german green tomato go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA Grown as a warm-season annual in all zones; transplant after last frost or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 aunt ruby's german green tomato 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 aunt ruby's german green tomato

Aunt Ruby's German Green Tomato is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Aunt Ruby's German Green Tomato hardiness — frequently asked questions

Is aunt ruby's german green tomato cold hardy?

Aunt Ruby's German Green Tomato is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA Grown as a warm-season annual in all zones; transplant after last frost (and sheltered UK gardens) aunt ruby's german green tomato can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature aunt ruby's german green tomato can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Aunt Ruby's German Green Tomato shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is aunt ruby's german green tomato?

Aunt Ruby's German Green Tomato is rated USDA Grown as a warm-season annual in all zones; transplant after last frost and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can aunt ruby's german green tomato survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA Grown as a warm-season annual in all zones; transplant after last frost or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect aunt ruby's german green tomato from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.