Re: Wisteria pruning - mastered

Dear all Medit-planters,

Yes, wisterias can be a real problem for gardeners unless you don't mind them completely taking over - the pergola, then the verandah, then the eaves, next the gables and finally the whole house. I've even seen them pushing through the gap between the floorboards and the architrave, and snaking through air vents in walls.

Generally speaking wisterias flower in two ways; one is that they flower sporadically at the ends of new growth, especially if the growth is secondary - after the first mad rush of spring growth; the other way is that they flower year after year on short side growths - spurs. This latter type of flowering is the one that produces the big spring show.

I have trained a number of wisterias successfully for over 20 years and hope my experience helps. I have a 25yr old standard 'tree' wisteria trained on one stem about 3.5m tall and 2m across. This is the common lilac variety. We also have a double cordon trained double purple wisteria that is about 20 yrs old. And I am starting with a long racemed white variety.

All the plants have been trained since birth by rigorous hard pruning year round. Once growths wanted to form the desired structure have achieved the necessary length they are pruned, all unwanted growth is cut out, rubbed away, removed. Side shoots that develop are rigorously pruned back to 2- 3 leaf nodes. Vigorous regrowth will develop throughout the growing season and it is necessary to keep this firmly under control using the same guidelines. After a year or two the plant gets the idea and produces more short side spurs and fewer long wild growths. But you still need to keep a watchful eye on older plants all summer long and deal with bits that threaten the shape and habit of the plant you want to achieve. All suckers from under the ground or around the base of the trunk are pulled away every time they appear. If done when the growths are green and sappy it is easy to get the whole thing with a hard yank; o/w there is a risk that more mature growths will have bits left behind that will produce a forest of suckers.

You also must provide a strong support pole for a standard - I use a steel tri-star fence 'dropper' that is 9ft long. About 3ft are driven into the ground. The double cordon has wires stretched pretty tight between the verandah posts. These plants are heavy with foliage and trunks so they need very strong support that is secure against strong winds. I FIND MY PLANTS DO VERY WELL WITH THIS 'TOUGH' ROUTINE.

Now, how could you treat an massive aged wisteria to recover control and get it managable? I have worked on a wisteria that is 140 yrs old; it had grown so large and wild that it had completely collapsed the hardwood and wrought iron pergola on which it was planted all those years ago. Our method was to survey the plant carefully to identify which single growth would be kept in reserve as the 'safe' viable bit. Then every last piece of the monster was chainsawed leaving only that part of the trunk with the 'safe' growth attached. It took weeks for the work crew to pull, tug, yank, cut, saw, prune and otherwise remove the wayward growths from the surrounding mature Lombardy poplars, tulip trees, ginkgos and lindens. There were hundreds of metres of it much of it as thick, and thicker, than a man's fore-arm. Next the ruined pergola was removed and a new one erected of 2 inch steel irrigation pipes set in strong cement footings. We waited then for signs of regrowth, fortunately it came very strongly and we were able to take charge of the 'new' plant as it developed, making it go where it was wanted - and only where it was wanted. Had it not done so we would have relied of the 'safe' bough to regenerate the plant. The plants are tough and very resilient; so much so I'd venture it is almost impossible to kill them unless through frost, freezing, drowning or conditions generally being unsuitable for these temperate region plants.

regards

trevor n
Trevor Nottle
Garden Historian, Garden Writer, Designer, Consultant
WALNUT HILL, 5 Walker Street, Crafers, SA 5152 AUSTRALIA
Tel./ Fax. 61 8 83394210

















































   



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