This post was published in March 2018, towards the end of the harshest winter in London for years.
You may have noticed – possibly with some alarm – the delicate, yet persistent blooms of the winter-flowering cherry which have been flowering for months now. The snow and ice of last week hasn’t been kind to them and many trees in London previously in full flower are now sporting a wilted coat of brown petals, but look beyond these and more flower buds are on their way!
A few years ago a trend began for planting early or late-flowering (depending on your point of view) Japanese cherries as street trees, and in some parts of town two closely related cultivars, like craft beer outlets, seem to be popping up on every street corner. Look out for the white flowered Prunus × subhirtella ‘Autumnalis*’ and the pink flowered Prunus × subhirtella ‘Autumnalis Rosea’
For the uninitiated, the sight of cherry blossom in the depths of winter has been known to elicit strong reactions from concern for seasons going haywire, to global warming incarnate. But, although I wouldn’t want to deny these very real climate change phenomena for which overwhelming evidence exists, the winter-flowering cherry could not in itself be defined as an indicator. It’s supposed to flower in mild weather from November through to April. And this season, trees in London have been particularly good, blooming consistently since November despite the see-sawing of temperatures within the space of a few days. So, despite it feeling wintry out there, there has not, until last week been a sustained cold patch and this appears to have been exactly what this tree likes.
Which leads us to the question: why does the winter-flowering cherry flower in winter? The short answer is it has been bred to, its flowers are not filling an environmental niche to take advantage of a winter flying bee, it’s flowering because humans wanted something to cheer them up during the gloomy winter months. Prunus × subhirtella is known only from horticulture with Japanese origins disappearing into the mists of time. It is sometimes also called Prunus subhirtella – note: no ‘×’ denoting hybridity – it’s unclear (as with many other ornamental cherries) what parent species have hybridised to create our tree. Sometimes too, it is called Prunus pendula, an appellation most commonly ascribed to another cultivar, the spring-flowering weeping Higan cherry. This though seems to be sloppiness and it should properly be called Prunus × subhirtella ‘Pendula Rosea’. Something else to look out for in Winter Flowering cherries is the last flush of blooms appearing in April with the leaves. These flowers differ from those of previous waves in having stalks – winter blooms are stalkless (or sessile).
Interestingly one of the world’s oldest Cherries, the 1,000 year-old ‘Miharu Takizakura’ in Fukushima province, is a weeping Higan and is often claimed to be the ‘most beautiful cherry tree in Japan’. This is a cultivar unknown as a London street tree, but it may bode well for the longevity of the trees we do have, not to mention their long term potential for craggy good looks.
As spring approaches, Winter-flowering cherries will be competing with other early flowering Prunus species, particularly the widely planted purple cherry plum (Prunus cerasifera) of either the ‘Pissardii’ (white blossom) and ‘Nigra’ (pink blossom) cultivars. If you’re lucky, you may see almond (Prunus dulcis) with big pink flowers, blireana plum (Prunus × blireana), with almost fluorescent pink blossom or another Japanese tree, Prunus × incamp ‘Okame’ again with pink blossom preceded by distinctive maroon coloured buds.
* The University of British Columbia Botanical Garden holds that ‘Autumnalis’ should actually be known by its Japanese cultivar name of ‘Jugatsu-zakura’