RHS updates hardiness rating system

The RHS is helping gardeners to adapt to our weird weather and the lower temperatures now experienced each winter. The Society has introduced a new, improved hardiness rating system to give gardeners a clearer idea of the temperatures specific plants can tolerate.

The seven-rating system will replace the current four-step scale, which was developed in the 1960s, and is available for thousands of plants.

The Society has been working on the new system for two years, in consultation with the UK’s garden owners, plant breeders and horticultural industry.

Recent climate changes and fluctuating temperatures have made it even more important for gardeners to choose the right plants for their conditions.

‘The original rating system has served us well,’ says Jim Gardiner, RHS Director of Horticulture. ‘But we have felt for some time that it doesn’t provide enough detail on degrees of hardiness. Today’s gardeners are much more aware of changes in the climate and are looking for more information.’




The American hardiness zones were also updated in 2012 and with recent storms and extreme weather it appears that even this map might even have to be reconsidered again in the future.





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- who has written 871 posts on My Climate Change Garden.

I am not an experienced gardener - more of an enthusiastic amateur who learns by trial and error and is keen to "manage" the effects of the weather on my garden. Writing this blog is my passion and I hope that it will continue to grow, allowing global gardeners to communicate about the effects of climate change on our plants and the future of our gardens.

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