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January 14, 2011 10:11 pm
How much damage has this extraordinarily hostile winter done to our gardens? It has certainly slowed us all up but the impact on the plants has been interestingly varied. For years I have studied alpine plants, blessing them for growing in foggy countries where they never receive the blanket of snow they enjoy on their home mountains. They have had a blanket this year, doubled over for extra comfort. They have been snug beneath it, and the blanket has been so thick that it has extended its hospitality to the bigger evergreens and shrubs too. How have they been doing?
Remarkably well, in my preliminary judgment. Hard frost with no snow is the supreme enemy but British shrubs have had a snow-coat throughout the worst of the freeze. Last year I lost quite a few hebes in February’s frost but this year I was even picking some faded flowers off a late-flowering winner, Hebe Nicola’s Blush, when December’s first snow-weeks melted briefly. Even after another four weeks of thick snow I have not lost this excellent low-growing little shrub. It has been consoling me near the front door with the thought that further away the damage will not be so bad.
Northern gardeners may be smiling wryly, but my hebes and I did not escape ferocious temperatures. Up to two feet of snow settled on the hedges and promptly froze into place. It was no use following the old advice and busily brushing off the snow’s weight with a kitchen broom. The lawns were so deeply snowed that my gumboots sank into them and made no progress. Here and there branches have bent or broken under the load, but most of them are on fast-growing monsters like the Leyland cypress. Sarcococcas bowed under what looked to be an impossible weight, but they have all sprung back now without damage. Mahonias lost all their early showers of flower but their stems have not broken or collapsed.
Out of the main windows I watch one of my evergreen favourites, the silver-variegated Rhamnus alaternus Argenteovariegata. Its name is its worst enemy. Against a wall it is a superb shrub, up to 10ft high if clipped yearly, and always a pale presence with its little leaves edged in cream-silver. Its hardiness is sometimes queried but my old specimen has grown on for 20 years and has just survived a heavy top-dressing of iced snow. It is essentially undamaged and the problem for this coming year will only be to remove the branches which revert to ordinary green leaves in the course of time. It looks particularly fresh and harmonious against a wall of grey stone and should be used much more often as a wall shrub. It is not safe as a freestanding plant.
By contrast, the ever-popular blue-flowered ceanothuses have suffered badly. Any evergreen forms which are now brown all over are unlikely to recover, those Italian Skies and Puget Blues which once seemed reliable risks. Several bushes of the fast-growing Gloire de Versailles have split badly under the weight of snow and they too will need replacing. Against walls the long-flowering AT Johnson has fared better and I notice that the excellent deep blue Edinburgh has been browned along the ends of its branches but not further down. I will replace my losses with these varieties, leaving Italian Skies to Italy.
Unlike ceanothuses, the quick-growing white-flowered Hoherias will regenerate from ground level. Three years ago I admired the small-leaved Hoheria Borde Hill in open ground and it has been spreading into ever more garden centres since then. My one plant of it grew so fast in 2008 that it needed the support of a stout central stake. In 2009 it flowered for the first time and I became overconfident. The frosts of early January 2010 turned it to a brown skeleton but by late July it began to regrow from the base and by November it boded well for 2011. It is now down to ground level all over again and I wait to see if it can repeat the recovery. The lesson is that hoherias should not be thrown out in a spring clean but that they are not reliable in an old-fashioned British winter.
There is next to no hope if your cistus bushes are brown all over and have dropped their leaves. They seldom recover and it is best to plan now for a replacement. Fortunately I have never depended on them at any important point in the garden’s scheme and for hedging I have preferred the excellent Osmanthus burkwoodii. For three weeks the hedges of it were iced with deep snow and I started to wonder if they would ever stand the strain. They have shaken off the problem and are as thick as ever, proving how good they are in British gardens. If you plant a new hedge of Osmanthus as a result, do not cram the plants too closely together, an interval of at least three feet between them being best. Above all, prune the bushes hard in each mid-May when the white flowers are over. The one weakness of an Osmanthus hedge is its willingness to go bare at the base if not pruned regularly. Otherwise its dark green leaves and density make a flowering hedge of hardy distinction, growing quite quickly to a height of five or six feet. This winter has stress-tested it to the limit.
It has also stress-tested the waxy green-leaved Pittosporums. Fancy varieties failed the test, especially those with bigger leaves or special variegations, but the plain green tenuifolium has survived, to my delight. It is the one which is such a good accompaniment to flower arrangements indoors, as our florists have taught us to realise. My buttresses of this basic Pittosporum have not suffered at all, proving that they are strong survivors in all but the bleakest northern gardens. The woody stems always look as if they might sulk if pruned but, unlike a cistus, they will regenerate if cut in late spring.
Even after a mechanical chopping with a powered cutter they settle once again into a thick wall of green growth. Here and there dead bits will need to be cut out this spring but in a sheltered bit of a garden the recent weeks have shown that Pittosporums are able to withstand surprisingly severe conditions.
Thanks to those conditions we are all weeks behind with the usual clearing and tidying. No doubt the cold will return but even if it does, keep despair at bay. While checking the roots of my unscathed young rosemaries I found snowdrops and early crocuses beginning to poke the first of their stems up through the soil.
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