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pruning a tibouchina (Princess flower) - help me make the cut(s)!

Posted by xanthoria 9 (My Page) on
Thu, Jan 22, 09 at 13:59

Hello everyone, can you help me?

The facts:
a) I have been given a tibouchina - about 10' tall and very airy/leggy, and leaning over a bit drunkenly.
b) It's been living in a full sun spot for several months now, in San Francisco, and flowering on and off.
c) I'd like to to be bushier.
d) I have pruning shears.
e) Here is a photo of it: Click for photo
f) I'm volunteer gardening some CalTrans land just to beautify my neighborhood - I can't afford to scrap the plant and buy a new one.

Now, imagine you are me, standing in front of this plant on a damp San Francisco morning with pruning shears in hand, and heart pounding. Where do I cut?

Also any tips for getting it to stand up a bit strighter? Just gradually adjust the pole it's tied to over a period of months?

Thanks for your help!

Follow-Up Postings:

RE: pruning a tibouchina (Princess flower) - help me make the cut

Wow. That is what I would call leggy. I can tell you that the tibouchinas that are dotted around the office park where I work in Menlo Park are cut back hard in early Winter if they suffer any early freeze damage. These are all planted close to buildings. The gardeners whack them very near to the ground, just leaving a few sticks in a vase shape, kinda like you would prune a rose bush. There is one just outside my window which is very thick and bushy (5' x 5') with a few flowers on it now. This one they did not need to prune at all. I like to think it is growing so well because it is outside MY window, but I'm sure the site and exposure (south & west) is the determining factor in its vigor and shape.
See what others say, but I'm thinking you whack yours back hard. Maybe just above where the trunk branches, cut back the side branches hard and the trunk too. A big vigorous plant like yours should put out new growth in Spring and then you will be able to shape that growth.

RE: pruning a tibouchina (Princess flower) - help me make the cut

  • Posted by catkim San Diego 10/24 (My Page) on
    Thu, Jan 22, 09 at 16:36

Caveat -- I don't have a Tibochina. But I agree with deep roots above: cut it to around knee height. It's much too lopsided to be more delicate with the surgery. Romove the stake and tape, throw away the circle of broken bricks. When it sends out new shoots, pinch them back occasionally so the plant is forced to bush out more. Two or three years from now, it should be sturdy and bushy.

RE: pruning a tibouchina (Princess flower) - help me make the cut

So, here's a pic with red and yellow prune lines - which should I do?

Are you sure this won't kill it???

RE: pruning a tibouchina (Princess flower) - help me make the cut

I also agree with deep roots,and would make the cuts where you have the red tape. At the yellow tape would not help the problem. Your plant looks like it has plenty of stored energy to push out adventitious buds from below the red tape. Send another picture next year. Al

RE: pruning a tibouchina (Princess flower) - help me make the cut

  • Posted by bahia SF Bay Area (My Page) on
    Sat, Jan 24, 09 at 12:07

Maybe a contrary recommendation here, but I would be less severe with the pruning, and cut back to the yellow lines, not the red. I'd also suggest using a good organic mulch and add alfalfa pellets or cottonseed meal, or fish emulsion fertilizer to get the plant to push new growth. In my experience with Tibouchina, they can sometimes shock when pruned back too hard, and fail to regrow. I'd agree that an established, in the ground plant that is healthy can usually be cut back hard and regrow well, but I'd be cautious with your plant. Tibouchina will also appreciate regular watering if the rains aren't consistent, and really does need summer water to keep pushing new growth.

RE: pruning a tibouchina (Princess flower) - help me make the cut

Where I live we don't prune until late in spring--if done too early later freezes will kill all new growth back, learned that the hard way, but fortunately these plants seem to be cast-iron, at least here in far northwestern part of the state (coastal Humboldt County.)

A few years ago, think it might have been '99 or 2000, all the tibs in the county were killed back right to the ground (or at least all I saw.) My friend thought he was helping me out by attaching a rope to the remaining roots and trying to pull them out with his pickup. Well, that certainly didn't work on the roots that were as big around as my upper arm and larger. It took another year but the plant came back with multiple shoots right from the ground as, I suppose, others did, too.

So, difficult to kill, I'd say, but don't prune until all chance of killing frosts are past, which where I live is 5/15.

RE: pruning a tibouchina (Princess flower) - help me make the cut

I thought I'd post a follow up picture now that the pruning is done. Click here to see.

I was able to get a trained arborist to help me! Thank goodness, because she pointed out a deep crack where the main trunk branches off, caused probably by the center trunk leaning. That crack was only going to get worse, and eventually split the trunk in two!

So, she cut that branch out altogether, and pruned the other two lightly. I will work on training the plant into a more upright form using the stake, too.

Hopefully in a few months all sorts of new growth will come up, and future prunings can be less remedial, and more aesthetic!

RE: pruning a tibouchina (Princess flower) - help me make the cut

It looks better without the branch. Tibouchina has a natural growth habit that tends to the gangly and always looks rather sparsely foliaged. The flowers are so beautiful gardeners put up with its non symmetrical shape. Al

RE: pruning a tibouchina (Princess flower) - help me make the cut

Well, it appears that the branch in the left in this photo has died since pruning :(

What should I do? Train the other branch to a more upright stance and hope it all fills in?

RE: pruning a tibouchina (Princess flower) - help me make the cut

Your diagnosis that the branch is dead I assume is because the rest of the shrub has leafed out. At this time I would wait before doing anything other than seeing to its nourishment as suggested by bahia. I have at times been tempted to remove a branch as dead when it was only slow to leaf after a cold winter. Al

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