Gardeners will have an updated roadmap to help them plan next year as Natural Resources Canada has released an update to its plant hardiness zones map.

The last map came out in 2014 and, since then, researchers say about 80 per cent of land in Canada has shown an increase in zones, typically between a half and a full zone.

In the simplest terms, the plant hardiness zone map shows what can grow where. The zones go from 0 to 9, and each zone is divided into two: a and b.

The maps are created based on data from seven criteria averaged out over a 30-year span: monthly mean of the daily minimum temperature of the coldest month, mean frost-free period above 0 C in days, amount of rainfall from June to November, monthly mean of the daily maximum temperatures of the warmest month, rainfall i

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