UK hardiness
Is Coreopsis 'Route 66' hardy in the UK?
Coreopsis 'Route 66'
More about coreopsis 'route 66' in the UK
Coreopsis 'Route 66' and the RHS hardiness rating
Coreopsis 'Route 66' is rated RHS H6 — hardy in a very cold winter, meaning it withstands winter minimums of about -20 to -15°C. In practice that means it fully hardy throughout the UK and into northern Europe. 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 coreopsis 'route 66' 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 coreopsis 'route 66' 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.
Coreopsis 'Route 66' UK hardiness — frequently asked questions
Is coreopsis 'route 66' hardy in the UK?
Coreopsis 'Route 66' is rated RHS H6 (hardy in a very cold winter, hardy to about -20 to -15°C). It fully hardy throughout the UK and into northern Europe.
Can coreopsis 'route 66' stay outside over winter in the UK?
In most of the UK, yes, if your garden's coldest night stays within its RHS H6 band (around -20 to -15°C). In colder inland or northern gardens, give it a sheltered spot, sharp drainage, and fleece on hard-frost nights.
What does RHS H6 mean?
RHS hardiness ratings run H1a (needs a heated glasshouse) to H7 (survives below -20°C). Coreopsis 'Route 66''s rating, H6, means hardy in a very cold winter — it tolerates winter minimums of about -20 to -15°C. The rating is an absolute minimum, not an average.
How do I overwinter coreopsis 'route 66' 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 coreopsis 'route 66' 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 coreopsis 'route 66' care
See the full coreopsis 'route 66' care guide, its temperature & humidity needs, and the US (USDA) hardiness version of this page.