Plant hardiness on the British Isles

As I was looking into what plants to plant in my garden once spring rears its head fully, I stumbled upon a map of hardiness zone in the UK. Now, plant hardiness zones are nothing new to me. I grew up in Sweden, where it was very important to check a plants hardiness before ordering seeds. Buy the wrong sort, and your plants would have no chance of surviving the winter. However familiar the expression is, I've never actually spent any time looking into it, so yesterday I decided that it was finally time to make a page in my garden journal dedicated to the topic.

The UK is covered by four hardiness zones, eg. zones six to nine. The Royal Horticulture Society here in Britain further divided these four zones into nine ranks, starting at H1a -that is the most cold sensitive tropical plants- and ending with H7. These are the fully hardy plants that can survive even the toughest of the European weather conditions, down to under -20°c!

For example, one of my gaols this year is to introduce Dahlias into my garden. Dahlias are perennial, but can't survive too harsh winters. I live in zone 8/9 which means that they will survive the winter here just fine. Had I been living in the Scottish Highlands however, I would have needed to take the dahlia tubulars indoors over the winter. So if you're unsure, make sure to double check your hardiness zones!