Jelitto Perennial Seeds: Tips & Tricks

Hardiness Zones

Please find the classification Z1 - 11 in our plant descriptions for your information about Winter Hardiness Zones: they give an approximate indication of the minimum temperature that a particular species can survive. Use this as a basic but not the end all for determining species suitable for your conditions. Other factors like soil and microclimates can influence winter hardiness to some degree.

Source: RHS Index of Garden Plants, USDA Online Plant Database, A. Armitage - Herbaceous Perennial Plants and others

Australia - Plant Hardiness Zones
Canada - Plant Hardiness Zones
Japan - Plant Hardiness Zones
USDA - Plant Hardiness Zones

Range of average annual minimum temperature for each climatic zone

Zone °C °F

1 < -45.5 < -50

2 -45.5 to -40.1 -50 to -40

3 -40.0 to -34.5 -40 to -30

4 -34.4 to -28.9 -30 to -20

5 -28.8 to -23.4 -20 to -10

6 -23.3 to -17.8 -10 to 0

7 -17.7 to -12.3 0 to +10

8 -12.2 to -6.7 +10 to +20

9 -6.6 to -1.2 +20 to +30

10 -1.1 to +4.4 +30 to +40

11 >+4.4 >+40

Range of average annual minimum temperature for each climatic zone
Zone	°C	°F
1	< -45.5	< -50
2	-45.5 to -40.1	-50 to -40
3	-40.0 to -34.5	-40 to -30
4	-34.4 to -28.9	-30 to -20
5	-28.8 to -23.4	-20 to -10
6	-23.3 to -17.8	-10 to 0
7	-17.7 to -12.3	0 to +10
8	-12.2 to -6.7	+10 to +20
9	-6.6 to -1.2	+20 to +30
10	-1.1 to +4.4	+30 to +40
11	>+4.4	>+40