A Gardener’s Diary: Training a wisteria vine

Time has a way of flying by. It is already three years ago this month that I wrote my first gardening column. Over these three years, I had many phone calls asking questions that I was very familiar with and were easy to answer.

I have enough garden books to open a library but some of them just don’t have the latest plant information that you can find on the internet. I can also find it faster than looking in the book index. The other day, a reader phoned me asking why his wisteria was not blooming. I read once that they are strong enough to raise a roof and they need a very good support. You have to wait at least seven years and maybe 15 years before they bloom.

Nigel Colborn from the U.K.’s Daily Mail website:

“The most commonly asked question among gardeners is “why won’t my wisteria flower?” The answer is seldom simple and not always helpful.

Some flower despite their owners breaking every rule in the book; others, though grown to perfection, refuse to produce so much as a petal. Common causes for poor performance include incorrect pruning, shady planting positions or weak variety. In full sun with young stems trimmed each August, the best wisteria varieties will always deliver. But unnamed seedlings or plants that are grown directly from the root-stock, rather than the graft, could take thirty years to bloom and even then produce stumpy racemes in disappointing colours.

“Rule one, therefore, is to always opt for a named variety. And it’s never a bad idea to buy your wisteria plant in May, while it’s in flower. Large specimens in tempting bloom will cost more than little plants but are a safer investment. If you can see them in flower, you’ll know what you are getting. So if it fails, your husbandry will be to blame rather than the plant.

“Most important factor to consider when growing wisteria is location. Wisteria is a twining vine that requires sturdy support and regular pruning to keep it under control. Open areas surrounded by lawn that can be easily mowed are ideal for growing wisteria. Wisteria doesn’t fair well in cold so make sure it receives plenty of sunlight.”

From Nikki Phipps’ Gardening Know How web site:

“While wisteria is great for covering an arbor or pergola, training wisteria vines makes it easier to control. Keep in mind, however, when training wisteria vines the variety may exhibit different twining characteristics. For example, Chinese wisteria (W. sinensis) twines counterclockwise while the Japanese variety (W. floribunda) is the opposite, twining clockwise.

“When training wisteria vines, select an upright stem and attach it to the chosen support. Remove any side shoots and continue to train the main vine upwards. New side branches can be trained as needed to fill in spaces of the support structure by attaching them where desired. For best results, keep these side branches spaced about 18 inches apart.

“Once the wisteria has reached the desired height, pinch off or cut the main vine tip to stunt its growth. Even trained wisteria vines require regular pruning; otherwise, wisteria will quickly take over everything in its path. Knowing how and when to prune wisteria is important. While regular pruning of new shoots throughout its growing season helps keep the vine manageable, wisteria requires a heavy pruning in late fall or winter as well. Remove any dead wood or crowded branches and cut back the side branches to about a foot or so from the main trunk. Also remove any suckers from its base.

For more information, call me at 250-558-4556.