UK Plant Hardiness Guide

How cold can your plants take it? UK hardiness is measured by the RHS rating scale, H1 (tender) to H7 (very hardy). Here's what each rating means, the winter temperatures it survives, which rating suits your region, and 340 hardy plants rated and ready for UK gardens.

Hardiest → most tender. Tap a rating to jump to its plants.

RHS hardiness ratings explained

Which rating do you need for your region?

A rough guide to the minimum hardiness to plant for across the UK — colder regions need a higher H number. Coastal and city gardens are milder than these averages; exposed and inland spots are colder.

H7 Very hardy below −20°C · 67 plants

Survives the coldest winters anywhere in the UK, including exposed uplands and the Scottish Highlands.

H6 Hardy — very cold winter −20 to −15°C · 112 plants

Tough through hard winters across almost the whole of the UK.

H5 Hardy — cold winter −15 to −10°C · 70 plants

Hardy in most of the UK; may want shelter in the very coldest gardens.

H4 Hardy — average winter −10 to −5°C · 23 plants

Reliable in an average UK winter; give protection in severe cold or northern gardens.

H3 Half-hardy −5 to 1°C · 19 plants

Comes through mild and coastal winters; needs a sheltered spot or protection inland.

H2 Tender 1 to 5°C · 34 plants

Frost will damage or kill it — overwinter under cover or grow it as a seasonal plant.

H1 Under glass above 5°C · 15 plants

Needs a frost-free greenhouse or a spot indoors over winter in the UK.

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