Winterhardiness zones

The zones refered to on our label are the EU plant hardiness zones, expressing the lowest temperature a plant still might survive during winter.
The USDA zones are from: http://planthardiness.ars.usda.gov. In general, Clematis can be grown in the garden at least to zone 11 in the USA. In warm USA zones, Clematis might have a summer rest.

Holland is in zone 8 which means that plants are hardy when on our label either zone 4 to zone 8 is mentioned.

EU zone temperatures in ºC
USDA zones temperature in ºC

4 Hardy to −30ºC on our label
     4a −34.4 to −31.7 ºC
     4b −31.7 to −28.9ºC
5 Hardy to −25ºC on our label
     5a −28.9 to −26.1ºC
     5b −26.1 to −23.3ºC
6 Hardy to −20ºC on our label
     6a −23.3 to −20.6ºC
     6b −20.6 to −17.8ºC
7 Hardy to −15ºC on our label
     7a −17.8 to −15ºC
     7b −15 to −12.2ºC
8 Hardy to −10ºC on our label
     8a −12.2 to −9.4ºC
     8b −9.4 to −6.7ºC
9 Hardy to −3ºC on our label
     9a −6.7 to −3.9ºC
     9b −3.9 to −1.1ºC
10
     10a −1.1 to 1.7ºC
     10b 1.7 to 4.4ºC
11 4.4ºC up