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October 11, 2013 7:15 pm
As usual there have been some heavenly autumn days for gardeners and for once I have got some things right. After last year’s cold winter we had a dahlia failure, like most of you. Their frost-proof shed turned out not to be totally frost-proof and the overwintering tubers turned to a soft mush.
As a result, the density of dahlias in the big borders has been toned down. The gaps have been filled by the excellent white-flowered annual Cosmos daisy Purity, the one that is taller than the usual Sonata.
The main surviving dahlia still to make a show is the superb clear yellow-flowered Glorie van Heemstede at a height of about 4ft. It matches the blue and purple Michaelmas daisies most effectively between a veil of white cosmos. Last year there were dabs of scarlet red from another dahlia, an old one called Murdoch.
Murdoch did not make it through the winter and packed up. In fact, life is better off without him. Next year, try Glorie van Heemstede with Aster Little Carlow, the king of all Michaelmas daisies, and drifts of Cosmos Purity. You will not be disappointed.
Elsewhere, the clematis have been looking great. I want to dwell on four of them, which are not in the least difficult. One of them is so familiar that you may simply forget to make it a first choice on an arch, pergola or moderately shaded house wall. Clematis Jackmanii Superba is a supremely good flowerer in late summer and early autumn. It is the clematis with masses of dark violet-purple flowers but it risks being crowded out by the many lesser varieties bred since. It is still an essential plant, happier in a well-fed, deep soil. Mine is looking predictably wretched after a dry summer in a silly place, some stony soil facing southwest without enough compost to help it. Everywhere else, this great clematis is flowering magnificently. It looks even better if you prune it back to about 2ft each February, the tough love that stops it becoming a tangled muddle too high up bare stems.
My other three clematis have been excellent, even in a season with a very dry August. I suspect that they would be good for those of you with summer bolt-holes in dry climates. They are brilliant in Britain in all weathers but are still not so familiar.
One of them, Clematis flammula, has finally solved my problem with narrow dry beds at the foot of south-facing walls. It grows fast but is easily containable. It has none of the preferences of other clematis for rich soil and regular fertilising. I cannot imagine it will ever be troubled by clematis wilt. Individually the flowers are not eye-catching but they appear in as much of a quantity as the flowers on its clematis cousin, the Travellers’ Joy, whose fluffy seed heads are so prominent in English hedgerows this very weekend. They are small, off white and prolific in August and are followed by pretty seed heads. After one year Clematis flammula is thriving where I have had all sorts of problems. First, a good scarlet-flowered honeysuckle, Lonicera Dropmore Scarlet, was decimated by aphids. Then a variegated trachelospermum died in the winter. Then something utterly inexplicable went wrong with a Buddleja Lochinch, which was supposed to be trained flat against the wall. It withered and looked wretched. Now, flammula has come to the rescue, needing quite a span and about 10ft of height. It solves the problem.
So, I hope, will an idea from Wroclaw in Poland that did not make it into my account of its botanical garden last week. Under trees in Wroclaw I saw big carpets of weed-blocking clematis, grown horizontally on the ground. They looked so pretty. They are Clematis jouiniana, the one with little blue-white flowers like the letter “x”. They seem entirely happy and block out the weeds. Life in Wroclaw is very much harder than life, even, with me in the Cotswolds. The winter temperatures regularly drop well below freezing. Summers are hot and dry and the trees above the clematis do not help. Nonetheless, Clematis jouiniana seems to flourish, much as it has been flourishing with me this autumn as an unplanned curtain on the face of a clipped yew hedge. It has a great growth spurt from July onwards and can be directed vertically or flat on to the ground. It then turns into a dreary blackened mess after heavy frost. The top growth should be cut down at once. It will never look pretty for a photo in winter after icy frost.
Will it solve my other long-running problem? I have four avenues of evergreen pears and a fifth of hornbeams, fanning out like the fingers on my hand. The tree roots make life difficult in the gaps between the avenues, although sweeps of narcissi seem to cope and reappear each spring. Evergreen acanthus is making some headway but I need a ground cover that will race away after the narcissus season and cover the intervening ground.
I have had so many false starts. I tried lavender when the trees were still small but it packed up when they began to grow big and had to be taken out. Crazily, I then tried masses of the sprawling scarlet-flowered Potentilla Gibson’s Scarlet, which promptly went on strike and flowered, if at all, in a curious shade of yellow, hating the drought and the increasing shade. The answer has been staring at me, meanwhile, on a nearby dry slope: mats of drought-resistant Clematis jouiniana. I first saw it exactly 50 years ago and promptly copied it into my notebook while still a schoolboy. I will now grow this old friend in the Polish style. Nurserymen used to separate an early-flowering form, jouiniana praecox, but it has failed to meet the criteria of the RHS Plantfinder. In these longer Octobers and sunny Novembers there is no need any more for an early-flowering selection. Buy the usual one and use it wherever you have dry shade or an eyesore. It is an excellent concealment for drain covers and so forth and can be allowed to scramble on to a low framework of chicken wire fixed on wooden pegs. When it dies back each year you can cut it away and be sure the drain cover is still in order.
My fourth clematis is having a wonderful season. Maybe I pruned Clematis Bill MacKenzie later than usual, as it has to be cut down yearly to about 2ft, preferably by late February. Maybe the late spring helped to hold it back. Anyway, I never remember this marvellous clematis and its hanging yellow flowers looking so good so late in the year. It is another one that will cope with a dry wall, facing south in full sun, although catalogues never tell you that fact. It is ideal for house owners in a hurry and needs only a sheet of broad-meshed wire, pinned to the wall, to direct it up in the right direction. It is flowering even now at its best, adding to the year’s colour-theming. A reader of the Financial Times immensely increased my delight in this great variety by writing to point out that its silvery fluffy seed heads look like the haircuts of Beatles enthusiasts, now approaching middle age. Behind the dahlias and the daisies, indeed they do, glistening in the sunshine like fans of “Yesterday” 50 years on.
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