Why Won’t My Wisteria Bloom?

Good question. It seems that while many people would like to have a wisteria bonsai, they give up on them when they fail to bloom consistently. After all, it is a rather dull looking plant when not in flower. I’m sure there are many non-blooming wisteria currently being used as umbrella racks.

'yaaaaaaAAAA!' ---The sound of a pleased wisteria owner

Wisteria bonsai fail to bloom for several primary reasons. The first is that people tend to repot them too frequently. Keeping the wisteria a bit root bound is important—in fact, you should not repot your wisteria more often than once every five years or so.

That’s the first thing. The second is that wisteria need a lake the size of China to be happy. Give your tree a lot of water by immersion of the lower part of the pot in water during summer. DO NOT leave them soaking year round. Without resting the pot in a basin of water the tree won’t flower much the next year. Oddly, the roots don’t rot. (In Japan they have watering drones called apprentices, who can water in their sleep if necessary. If you don’t own a drone, and don’t wish to water 28 times a day yourself, it is perhaps best to use the immerse technique for the summer growing season.)

These first two practices must be combined: If you don’t repot frequently, the soil will get compacted (which we want for good flowering) but that compaction will make it very difficult to water sufficiently from the top when the tree needs a lot of water, in the summer. Hence the pan underneath.

The third thing to promote consistent blooming is to be careful when and how much you’re fertilizing. It is best to fertilize strongly AFTER FLOWERING (April/May) until about July, and then slack off. That way your flower buds will set for next year, and you will restrain foliage growth over the summer.

Lastly, the wisteria will usually produce some tendril growth, which if encouraged will shift the plant into a vegetative growth habit and reduce flowering. Nip these tendrils back to prevent too much growth.

Keep the darn things in the sun. Put up big fans to keep the clouds away. And then watch them bloom.

Maybe I should have titled this one ‘Preventing the Umbrella Rack!’ —but that would have been only slightly better than last week’s overly ambiguous title.

18 Comments

  1. Mark Leija says:

    Ohh! Now I get it!! Thanks Michael!!!

  2. Travis R says:

    Do you know why my wisteria would abort its flowers? The panicles form and start to lengthen –maybe even a couple will flower– but soon they stop growing and then dry out. Is that a water issue too?

    • crataegus says:

      There are several reasons why this might happen—lack of water is one, but also be sure about fertilizing, repotting too soon, etc. —essentially, try to follow this regimen, and see if you have better results.

  3. Chris Glanton says:

    Very timely Michael! I’m getting one from Bill Vilvanis in March. I didn’t know they were so demanding of water and root compaction. Excellent information!

  4. terry davis says:

    You could also get a strong bloomer, such as “Sweet Repeat” aka “Southern Belle”

  5. Gerald says:

    Michael,

    I had come across these two videos a couple years ago while researching care for a wisteria in my yard. I thought this was interesting and have always kept it in the back of my mind for my wisteria bonsai. Just thought I’d share:


  6. Maxine Frieze says:

    Thank you so much for your advice. Summer 2013 in London, UK, was VERY long and hot, so I kept my Wisteria Bonsai pot in a pan of water, and let 2 new runners grow a little. This Spring (2014) I have the most glorious Bonsai Wisteria in FULL flower. It’s height is about 2ft. Such joy after waiting 22 years.
    I am now doing a similar thing with my Blue Jacaranda growing in a pot, though it is about 6ft tall.

  7. thomas says:

    what exactly do you mean by tendril growth or vegetative growth?

    • crataegus says:

      After blooming the plant may just throw out some leaves at the base of the flower raceme, which we might call vegetative growth. Tendril growth is different, and is a long extension that also has leaves. Both types might happen on the same plant.

  8. Cara says:

    I live in the desert southwest [about 20 miles north of the US/MX border in AZ].
    I love this article and the videos about pruning too. My question is this: Is there anything special I need to do for the wisterias because they live in the desert? I am getting pans for them to keep them in water. They were going to get re-potted this week but I’ll wait on that. I have them potted up. Not in bonsai pots because of the intense heat and low humidity they needed to be in bigger deeper pots [all my trees are potted up]. When I first moved here I lost several trees because the climate was too inhospitable and I didn’t know how to deal with the changes and there is no one around here to advise me. So what I’ve learned has been by experience and the price has been high.
    But my two wisteria [about aged 15] have survived nicely but never bloomed.
    So I want to do everything I can to give them the best chance to bloom next spring.{I don’t even know their color!}
    Thanks

    • crataegus says:

      I never grew wisteria down there, but I remember seeing them growing as yard plants when I lived near Tucson years ago. Good idea to have a pan of water under them when they’re growing. You might want to be careful about the water hardness, though, when doing that. There won’t be much ‘flushing’ going on and you don’t want salts to build up. But just the fact that they do well down there says they’re probably less limited by water hardness than other things.

      Wisteria can simply be very reluctant to bloom sometimes. Yours should be old enough, just try the things I mention and I hope you have good luck. They love sun, like pines. If you keep them too shaded then they putter a bit. Good luck!

      • C. Sims says:

        Thanks. I am going to do the water pan thing and see to the pruning techniques. One thing I don’t have to worry about is them getting enough sun. I live at 4645′ and they are in the sun.  As I said I will try the water pans and pruning techniques. The bottom line is as much as I want them to bloom if they don’t ‘c’est la vie’ after fifteen years together I love them anyway. I’ll let you know how the August pruning goes, or should I wait ’til September? I am just north of the border in Cochise County and it doesn’t get cool until December.     Cara

      • crataegus says:

        Don’t cut too late or you may cut off flower buds. And don’t cut too short. When the extensions have run a while, a couple feet maybe, then cut back. Good luck! In your area you might get several flushes of growth before they stop in the fall. So you may be cutting earlier, June or July.

      • Cara says:

        How will I be able to tell when the time is right?
        I used to just chop off all of the runners because they got so think and out of control. But this year I am to leave the cutting until the big one in late summer?
        I really want them to bloom, but I am beginning to see the fault lies with me, not them.
        One nursery “expert” told me a couple of years ago to just throw them out if they hadn’t bloomed by then. Seriously? I have relationships with my bonsai.
        So even if they don’t bloom again, I will still nurture them.

  1. […] you ever thought about growing a wisteria bonsai? It can bloom if given the proper care: http://bit.ly/Aj5T6gTwitterFacebook […]

  2. […] you suffering sleepless nights because your Wisteria won’t bloom? Suffer no more! Thanks to Michael Hagedorn, your problem is easily solved (well… sort of). In fact, Michael […]

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