So we've just had our first real blast of winter with temperatures dropping below zero right across the UK with temperatures dipping to -17c in the Scottish Highlands. Obviously that's the extreme, but many areas of the UK from Northumberland to Somerset, Kent to Cambridgeshire saw temperatures at or below minus 10c and this was accompanied with snowfall in many areas.
What's been just, if not more concerning for many exotic gardeners has been the lack of daytime recovery temperatures. It remained stubbornly cold in the day for a full week including several ice days. These are 24 hour periods where the air temperature does not reach 0.0c and remains sub zero.
In my garden we had almost three continuous days when the temperature didn't rise above 0.0c with several more days when we had frost and ice remaining on the ground and plants. Plants were frozen through for a full week, if not more! How will they cope?
Luckily my gardens absolute low so far has been -5.4c which isn't low enough to outright kill the foliage of any of my evergreen backbone plants. Others haven't been so lucky. This has been a pretty cold spell but nothing exceptional. It may be a shock for new exotic gardeners. The last cold weather was the Beast from the East of Feb/March 2018 and before this the winters of 2010-13. (2010 being the coldest in 100 years with snowfall across all the UK at the same time)
This cold spell shows, that although winters are generally getting milder and milder, cold winters aren't a thing of the past.
For years I have produced overwintering videos on my youtube channel most cover all eventualities regarding winters. Quite often the protection suggested isn't always needed if we get a mild winter. But as we have already seen this winter, protection has most certainly been needed! Not only that but the temperatures have been too severe for many plants in some gardens. There's been reports of blackened Washingtonia palms, collapsing Cordylines and mushy Agaves. Even with a lot of protection, sometimes a plant is beyond the limit for some locations.
The trouble with British winters is that they are usually benign, neither especially cold or especially mild. They oscillate between mild-ish to coldish but never extreme compared to say the tropics or the Artic. In the tropics there 's never a risk of frost (at low latitudes) and in the Artic you wouldn't even try to get a palm tree through a winter outside. What I'm trying to say is that our winters aren't really that extreme but also not 100% predictable. We don't get the really reliably cold winters that continental areas get so we don't prepare for the worst every winter so many of us either don't protect plants enough or try growing more and more half hardy that get blasted when we get a slightly colder winter.
I try and grow a large range of plants, probably a larger range of exotic looking plants than many people would expect for my location in West Yorkshire. I'm pretty lucky that my climate is normally quite mild in winters. Even in the awful winter of 2010 we ONLY saw -10c when a lot of the country saw -10 to -20c even in the south for days at a time. I'm under no illusion that I wont get a really bad winter at some point in the future. If I do get a -10c or lower I know that all my half hardy plants will be killed outright. But I know I have enough truly hardy plants in the garden as well as enough herbaceous and seed grown plants to keep the tropical look.
Currently my rarest planted out plants were protected during the coldest nights including the Trachycarpus oreophilus above.
The none woody tender plants like Dahlias, Gingers and Cannas have all gone to mush as expected. The rhizomes under the soil will be fine and will grow away to give their usual great display next summer. At the time of writing next summer seems a long way away....
Before we get there we've got the rest of winter to get through. January and February are usually colder than December..... We could be in for a very long winter with more cold spells on the horizon....
You may have noticed from the photos I've not protected my Musa bananas even after repeatedly making videos about how important it is to do this to keep the height. There's a good reason why I haven't and all explain all in a forthcoming blog......