Weeping with Wisteria…

Wisteria floribunda 'Blue Eyes'It’s the third week in May, and the Wisteria floribunda ‘Blue Eyes’ which covers our pergola has begun to drip with fragrant blossoms. It’s certainly a sight, and elicits ooh’s and ahh’s from nursery visitors. Conversation immediately turns to pruning advice, and the question we hear over and over again, “Why hasn’t my Wisteria ever bloomed?”

We’ll cover extensive pruning Wisteria advice in a later blog posting, but let me address the flowering question. Wisteria often take several years to bloom after transplanting as it  is concentrating energy on establishing a firm root system, but there are other points to consider. First, plants should receive a good 6 hours or more of sunlight. Also, do not fertilize with a high nitrogen fertilizer. Wisteria are in the legume family, and fix their own nitrogen from soil. Select a fertilizer with a high phosphorus # (the middle number) such as 5-10-10, 5-10-5, or  Espoma’s FlowerTone which is a 3-4-5.

It is advisable to select named clones which have been propagated from productive flowering stock. Wisteria grown from seed are quite variable in their blossom production, and some have been known to never produce a bud. Another thing to consider is that Wisteria sets buds on old wood, and should be pruned  in late spring after flowering (or when it should have flowered) to about 6″ from main branches. One other trick is root pruning in early spring. Using a sharp a spade, dig in about a 2′ radius from the base of the vine. This will sever the roots and may shock the plants into flowering.

5 thoughts on “Weeping with Wisteria…”

  1. Sever the roots and shock the plants. Oh my. Doesn’t sound like a Tracy technique to me. I’ve always known them to be kind and gentle with their plants. Hee hee. We’ll be down in So. Dart this weekend. Then we’re off on a cruise to Alaska:-) I’ll be by to buy some veggie plants after we return on June 17th. Until then, be well and be productive!

    Leslie

  2. Thanks Tracy for your tips on root pruning and and heavy handed with super phosphate. I have finally gotten flowers for the last 3 years. However, they come out at the same time as the leaves, and I see others that are just masses of flowers, with leaves coming after.
    I will follow your pruning technique. Maybe that will do it. I had been told to prune 2 nods back from the old wood.
    Thanks for the tips.
    Debby

  3. Right now we have Wisteria ‘Blue Moon’ in stock, which is a lovely form with a heady fragrance. ‘Blue Eyes’ is a selection we purchased at the Arnold Arboretum plant sale 20 years ago, and I’ve never seen it offered elsewhere. We will be digging some of the runners of ‘Blue Eyes’, and should have some for late summer sales.

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