[Answers.com, by the way, says “Although the Thames may have frozen slightly since 1814, with rising global temperatures, the demolition of London Bridge and the embankment of the river, it is unlikely it ever happened to any great degree and certainly not in the 20/21st centuries.” – Shows what they know, I was there. Idiots.]
Anyway, Britain is grinding to a halt after the sort of snow we get in Pennsylvania every winter. (Unfortunately, that snow blower went bang in a cloud of smoke and blows no more...) But let’s be fair, the Brits can’t have flotillas of snow plows waiting 45 years to be us, the taxpayers wouldn’t stand for it. But the temperatures at one Scottish weather station have been down to -6F/-22C and more snow is forecast this week. We have freezing rain here in PA and at this desk is a man wondering what will grow in the very coldest parts of the country.
For recently I’ve been revising one of my books that’s been out of print for a while and been doing some new research on plants that grow in cold gardens. Of course Britain is positively balmy (mostly in zone 8) compared with, say, parts of Canada’s Yukon Territory, Alberta, and Saskatchewan which are in zone 1 where winter temperatures are below -50F/-46° C. The coldest parts of the USA are a little less cold, in zone 2, and include Alaska plus a few mountains in Wyoming and Montana.
So there’s cold – only just below freezing in my home town in Britain this last week – and there’s cold.
So what grows in zone 2?
Well, the United States department of Agriculture suggests these plants – for zone 1: Betula glandulosa (dwarf birch), Empetrum nigrum (black crowberry), Populus tremuloides (quaking aspen), Potentilla pensylvanica (Pennsylvania cinquefoil), Rhododendron lapponicum (Lapland rhododendron) and Salix reticulata (netleaf willow). Nothing outstandingly flamboyant, there, I have to say.
But step up to zone 2 (-40 to -50F/-46 to 40C)) and the choice is unexpectedly impressive. There’s the short USDA list and there are suggestions on the Ground Effects (wholesale) nursery website and you can search Rare Find Nursery listings by hardiness zone.
It’s interesting to see that different sources don’t necessarily agree but the two standouts for me, plants that would really cheer me up after all those months of snow are lilac and creeping phlox.
Rare Find suggests most, but not all, of their varieties of the familiar common lilac, Syringa vulgaris, are hardy down to zone 2; Ground Effects suggests that four forms of moss phlox (P. douglasii and P. subulata) are also tough enough for zone 2. The big fat American Horticultural Society A-Z Encyclopedia of Garden Plants does not agree. What do you think? Any recommendations for plants to take the most ferocious winters?
And finally, I can’t talk about plants for cold climates without recommending Kathy Purdy’s superb Cold Climate Gardening blog.
Rare Find's recommended zone 2 lilacs: Syringa vulgaris 'Agincourt Beauty', 'Firmament' (above left), 'Frederick Law Olmsted'. 'Krasavitsa Moskvy' (above right) and 'Lucie Baltet' plus the hybrid repeat flowering Josee™ ('MORjos 060F').
Ground Effects (wholesale) nursery recommend Phlox douglasii 'Crackerjack' and 'Rose Cushion', and P. subulata 'Crimson Beauty' and 'White Delight'. Phlox subulata 'Scarlet Flame' (above) is also reckoned to be hardy to zone 2.
Other nurseries also allow you to search their listings by zone.
Lilac pictures courtesy of Rare Find Nursery.