What plant hardiness zone is Bister

Bister is located at Östlich Raron, Valais (Wallis) (VS), Switzerland.

Plant hardiness zone (winter frost zone or gardening zone) for Bister is 6b by the USDA scale.

Coldest zone's winter temperature is −20.6 … −17.8 °C.

Plants of 6b USDA hardiness zone suitable for outdoor gardening and growing in this winter frost zone 6b USDA.

Alternative climatic zone of gardening for Bister by UK RHS scale is H6.

Plants of H6 RHS hardiness zone suitable for outdoor gardening and growing in this winter frost zone H6 RHS.

Bister VS @ wikipedia.

* The lowest temperature in Bister was -20.3 °C on 27/02/2018.