Pruning Viticella Clematis
07/05/2008
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Although growth in the garden this spring is 2-3 wks later this year [2008] than last, most of the viticella clematis are making welcome new growth. All herbaceous and viticella clematis flower on the new season’s growth and I cut them down in December here, rather than wait until early spring. Most are cut to the ground, just above the lowest pair of buds and always in their first year to encourage multiple new shoots from below ground, making them less vulnerable.
After a year or so, I may I have left one or two mature stems to 2ft or more so that they reach the netting or have a head start up their host shrub, for example the blue C. vit. ‘Perle D’Azure’ up a golden Elder.[ See clematis gallery] After 2 or 3 yrs these stems become thick and fibrous, but by leaving them, there is a real danger of frost damage. The stem freezes and expands, [particularly when exposed to the sun] blasting the fibres apart, and encouraging a mould growth that can travel down the stem leading to loss of the plant.
I thoughtlessly left the 2 thick stems of my vit. ‘species’ through the winter without cutting back, thinking that it was very tough, being the species. But one stem has been reduced to shreds, and there is no sign of new growth even on the more solid looking stem, so I fear it’s loss but hope that something will erupt from below in time. I have cut the stems to the surface and applied something anti fungal, but horses and stable doors come to mind!
What I usually do is to leave one mature stem and cut others down. The following year a newer thinner woody stem is left, and the older one is cut, so that none are left to get too thick- ˝ ins is probably too thick. I am considering cutting all stems to the ground in future and making sure that there are plenty of twigs for new growth to reach the support. However, another reason for leaving some longer stems is the vole/ mouse nuisance in spring [not to mention rabbits!] as they just love to shred up soft new growth, a diagonal cut is diagnostic. This damage is not fatal, and may even stimulate more desirable multi stem growth, but flowering will be later, and repeated damage could seriously weaken a young plant. I would always recommend buying larger and stronger plants for this very reason.
Protecting new stems with smooth plastic tubes, as used for young trees, prevents voles from climbing up to vandalise delicate stems. Clay pipes can be used but snails find them a perfect over wintering den with the perfect spring breakfast!
All my clematis have already had a handful of Suphate of Potash and a thick ‘donut’ of well rotted cow manure put around the base to help retain moisture - but taking care to keep it 4 or 5ins clear of the stems.
The next job is to tie in new growth, avoiding damage to tender stems, and try to keep up with the growth surge in May, so that the clematis is spread out roughly where I want it, rather in one big tangle. But they are worth it!
