Greetings
Reading northern/southern hemisphere books pertaining to planting/harvesting/pruning/horticultural practices/gardening/permaculture design etc. in the southern/northern hemisphere can be confusing with reference to the months/seasons. This is due to the six month offset of the seasons and the differences between the meteorological and astronomical definitions of the seasons.
Meteorologists(NZ) divide
seasons into periods of three whole months based on average monthly
temperatures. Astronomers define seasons with two solstices (shortest day and longest day) and two equinoxes (when day time and night time are of equal length). Astronomers use the earth's tilt and the sun's alignment over the equator to determine the dates for each event.
The table below has been designed to facilitate interpretation of months and seasons for each hemisphere and seasonal definition.
Click on image for larger version or download PDF.
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| Month/Season Calculator |
2025-05-29
American resources pertaining to planting/harvesting/pruning/horticultural practices/gardening/permaculture design etc. use the USDA Hardiness classification system to divided geographic areas that have similar long-term average annual extreme minimum temperatures into 13 zones. New Zealand covers 8b to 11b.
Zone 8b: −9.4°C to −6.7°C
Zone 9a: −6.7°C to −3.9°C
Zone 9b: −3.9°C to −1.1°C
Zone 10a: −1.1°C to 1.7°C
Zone 10b: 1.7°C to 4.4°C
Zone 11a: 4.4°C to 7.2°C
Zone 11b: 7.2°C to 10.0°C
Chew
