Gardening Journalist

Country Life

Replacing the ties that bind
Keeping a watchful eye on plant pests and training wisteria and grape vines.

Wisteria Pruning

Charlbury Station, Oxfordshire Here in Oxfordshire, as in most parts of the country, we have had a proper cold winter for a change. I was talking to Roy Lancaster on the telephone recently, and we agreed how welcome it had been. His conclusion was: 'Fair exchange for a good bug killer'. Well, which nasty insects can we hope have succumbed to the cold?
According to the Royal Horticultural Society, indigenous insects are not affected by a cold winter - only those that have come over to us from warmer climes that have survived recent mild winters. The populations of rosemary beetle (from the Mediterranean) and the berberis sawfly, for instance, may prove to have been reduced during these past cold months.

The gardener's bonus, pest wise, is a late frost which catches emerging insects unawares, although such freezes are inevitably at the expense of treasured spring flowers, such as wisteria. Personally, I would rather have the wisteria flowers and the insects too.

I am expecting a number of plant casualties this spring, encouraged as we have been to plant exotica from milder continents, following a run of mild winters. Complacency has got the better of me. In recent years, I have left my dahlias in situ instead of lifting them, with no apparent ill effect. I place large plastics containers and glass cloches over some of them, in an attempt to keep the tubers drier and warmer. All will be revealed as the shoots start to emerge in a few weeks or not.

Over an arbour at the end of a cross vista, I have trained a delightful ornamental fruiting vine with purple leaves and black fruits, Vitis vinifera Purpurea. I was first made aware of this superior climbing plant as a child. It had been trained along a stone balustrade flanking the '100 steps' at my mother's old home, Shrubland Hall in Suffolk . In late summer and autumn, it is a sigh to behold when bathed in sunshine, the purple foliage acting as an excellent foil against the black grapes.

Up until last year, I had always pruned the side shoots from the main rods of this vine and other fruiting vines in January, carefully leaving one or two buds, but was told that many French vineyards do differently. Apparently, they cut flush to the older wood, presumably to produce better fruit. So that is exactly what I did last winter to see if it made any difference. If anything, the bunches were a little more plump. I always leave the rotting fruits in autumn for hungry birds, and as a last sugary snack for all the brave butterflies still on the wing.

We all lead such busy lives that sometimes jobs have to be done during one of those rare spare moments, even if the timing isn't perfect. There are certain things you should never do, such as prune a tree as the sap is rising in the spring, but I have learned a shortcut when it comes to wisteria. The textbooks tell us that there are two distinctive annual pruning operations in August and March, the cutting back of new shoots produced that summer to within six leaf nodes of the older wood during the former month, and to within two leaf nodes during the latter.

I find it easier and quicker and it has made no difference whatsoever to the flowering performance of the plant, to prune it back all at the same time in Februrary or March straight back to the recommended two nodes. It is much easier to keep a wisteria neat and tidy if you have been able to train it to shape ever since it was first planted, as I have been able to do for the last 10 years. It is more difficult to do so if you inherit a mature specimen that looks like a ball of knitting that a kitten has been playing with.

I have trained mine into two neat horizontal tramlines, running to the left and right from the centre of the stone building, tied to heavy-duty galvanised wire threaded through stout vine eyes drilled into the wall and secured with plastic rawl plugs. I have tied this main framework to the wire with varying types of tree ties and Flexi-tie to support it as it becomes heavier with age, until such time as it becomes self supporting. This is not a job for green string because it needs replacing every other year. There's enough to do without having to constantly replace ties. I use old, flat, brown shoelaces on climbers, trees and shrubs. They're nice and soft and last for years.