Cold hardiness & minimum temperature

Is Tuberous Begonia 'Nonstop' (Begonia x tuberhybrida 'Nonstop')cold hardy? Hardiness zone & min temp

Also called Nonstop Tuberous Begonia.

More about tuberous begonia 'nonstop'

About Tuberous Begonia 'Nonstop'

Begonia x tuberhybrida 'Nonstop' · also called Nonstop Tuberous Begonia · flowering

The 'Nonstop' series are compact tuberous begonias bred for masses of large, double, camellia-like flowers in vivid colours from early summer to frost. Grown from tubers, they thrive in shade-to-part-shade containers and baskets, die back for a winter rest, and can be stored dormant and regrown each year, making them a reliable bedding and patio favourite.

Cold limit: USDA 9-11 in ground; elsewhere lifted and stored frost-free over winter · RHS H2 (13-24°C)

Watch for — Tuber rot: Soft, blackening tuber from overwatering or burying it too deep; plant shallow in free-draining mix and keep storage tubers dry and frost-free.

What tuberous begonia 'nonstop''s hardiness rating actually means

Tuberous Begonia 'Nonstop' 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 9-11 in ground; elsewhere lifted and stored frost-free over winter — 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. Tuberous Begonia 'Nonstop' shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for tuberous begonia 'nonstop' 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 tuberous begonia 'nonstop' go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 in ground; elsewhere lifted and stored frost-free over winter 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 tuberous begonia 'nonstop' 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 tuberous begonia 'nonstop'

Tuberous Begonia 'Nonstop' 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.

Tuberous Begonia 'Nonstop' hardiness — frequently asked questions

Is tuberous begonia 'nonstop' cold hardy?

Tuberous Begonia 'Nonstop' 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 9-11 in ground; elsewhere lifted and stored frost-free over winter (and sheltered UK gardens) tuberous begonia 'nonstop' can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature tuberous begonia 'nonstop' can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Tuberous Begonia 'Nonstop' shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is tuberous begonia 'nonstop'?

Tuberous Begonia 'Nonstop' is rated USDA 9-11 in ground; elsewhere lifted and stored frost-free over winter and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can tuberous begonia 'nonstop' survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 in ground; elsewhere lifted and stored frost-free over winter 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 tuberous begonia 'nonstop' 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.