UK hardiness
Is Giant Red Celery hardy in the UK?
Apium graveolens
More about giant red celery in the UK
Giant Red Celery and the RHS hardiness rating
Giant Red Celery is rated RHS H5 (withstands moderate frost once established) — hardy in a cold winter, meaning it withstands winter minimums of about -15 to -10°C. In practice that means it hardy through most of the UK even in severe winters. The RHS rating describes an absolute minimum temperature, not an average: a single hard frost below its band is what does the damage, so the question is always "what is the coldest night my garden gets?", not "what is a typical winter here?".
This follows the RHS plant hardiness rating system (H1a–H7), the UK standard. For the US growing-zone view, see the giant red celery USDA hardiness guide.
Does UK region change it?
UK winters vary far more by locality than by latitude. Mild western and coastal areas (the south-west, Pembrokeshire, western Scotland's coast) and urban heat islands run several degrees warmer than inland frost pockets, valleys, and exposed eastern sites at the same latitude. A plant marginal on its RHS rating often survives in a sheltered town garden but fails 20 miles inland — so judge by your own coldest recorded night and microclimate (a south-facing wall, a courtyard) rather than the regional average.
Overwintering giant red celery in the UK
For a borderline-hardy plant, the UK winter killers are not just cold air but cold wet roots and wind. Improve drainage before winter, mulch the root zone, move containers to a sheltered spot or against a warm wall, and use horticultural fleece on hard-frost nights. Established plants in free-draining soil take far more cold than a recently planted one in heavy, wet ground.
Giant Red Celery UK hardiness — frequently asked questions
Is giant red celery hardy in the UK?
Giant Red Celery is rated RHS H5 (withstands moderate frost once established) (hardy in a cold winter, hardy to about -15 to -10°C). It hardy through most of the UK even in severe winters.
Can giant red celery stay outside over winter in the UK?
In most of the UK, yes, if your garden's coldest night stays within its RHS H5 (withstands moderate frost once established) band (around -15 to -10°C). In colder inland or northern gardens, give it a sheltered spot, sharp drainage, and fleece on hard-frost nights.
What does RHS H5 (withstands moderate frost once established) mean?
RHS hardiness ratings run H1a (needs a heated glasshouse) to H7 (survives below -20°C). Giant Red Celery's rating, H5 (withstands moderate frost once established), means hardy in a cold winter — it tolerates winter minimums of about -15 to -10°C. The rating is an absolute minimum, not an average.
How do I overwinter giant red celery in the UK?
For a borderline-hardy plant, the UK winter killers are not just cold air but cold wet roots and wind. Improve drainage before winter, mulch the root zone, move containers to a sheltered spot or against a warm wall, and use horticultural fleece on hard-frost nights. Established plants in free-draining soil take far more cold than a recently planted one in heavy, wet ground.
Does UK region change whether giant red celery survives?
UK winters vary far more by locality than by latitude. Mild western and coastal areas (the south-west, Pembrokeshire, western Scotland's coast) and urban heat islands run several degrees warmer than inland frost pockets, valleys, and exposed eastern sites at the same latitude. A plant marginal on its RHS rating often survives in a sheltered town garden but fails 20 miles inland — so judge by your own coldest recorded night and microclimate (a south-facing wall, a courtyard) rather than the regional average.
More giant red celery care
See the full giant red celery care guide, its temperature & humidity needs, and the US (USDA) hardiness version of this page.