British Columbia: tibouchina (princess flower) pruning them

Hi everyone.
I have three Tibouchinas which I bring into the greenhouse (55degrees) from october to whenever it warms up outside (May-ish). For the past two years they bloom in the greenhouse but never outside! So, right now they're in full bloom and have been since late october. Can I prune it now? and hope that that will make them bloom in the summer?
I only water them once a week when it's in the greenhouse and do not use fertilizer until they're outside. (I use liquid fertilizer)
thanks!

 

You can prune now, but do not remove more than 20% of the new growth. In my experience, they bloom on first-year growth.

I'm not sure about how Tibouchina work in the Northern Hemisphere - here in the Southern, they are summer flowers, so I'm not surprised that they only bloom for you in your winter.

Best of luck!

 

thanks :)
I wish I was in your hemispere!
What about those little thin branches that poke out the side, they're as thin as spaghetti and short, should I snip those off or with they become useful later on?

 

If you ever visit Butchart Gardens or Stanley Park's rose garden, which has Tibouchina inter planted amongst roses and other flowering plants, in the summer T. blooms... Is your green house heated above 15c? I would not encourage growth until mid March. It sounds like your plants have the stored energy from the previous growing season, to provide you with the fragrant blooms in winter, which is telling me that that perhaps the plant needs more heat in its' summer location or that the cycle has been reversed because of the former.

 

Does "not encourage growth until mid March" mean I should prune in mid March?

 

If your current growth is leggy, I wouldn't want to encourage more... your plant should be semi dormant right about now... pruning now may encourage more leggy growth if that is what you have succeeded in doing throughout the winter...., but if you want to risk this, and I having not seeing the plant up close and knowing it's history, you have to make an educated decision, what is it you want to achieve? Continue with winter only blooms or experiment with summer blossoming...? Ron B is the expert...

 

thanks K Baron,

I want to experiment with summer blossoming. The history behind them is they've never been pruned. They are about 6 feet high. The green house is 55 degrees (almost 13 celsius). And when outside they are in direct sunlight. I want to do something to make them "reverse" to the normal cycle (without killing them of course). would a photo help?

 

A photo wouldn't hurt, also, other avid gardeners may contribute/ confirm and direct the appropriate course of action... :)

 

Here is what two of them look like, finally :)

 

Hi Erika...

NOOOOOOOOOOO, always make your indoor/outdoor subtropical plants similar to a topiary.... You need to prune to only one main stem, and go from there.... this is why you are never getting summer blooms... sorry to be the bearer of bad news....

 

Hi K Baron,

oh crap, really? I'm scared to cut everything back to one main stem...eep. how much (percent-wise) should I take off?

 

Reduce to one stem.....Before you do anything, you may wish to visit Butchart Gardens nursery ... they must have specimen of Tibouchina in their greenhouse plantscape and a green gardener to refer to....?

Also, remember to repot in a smaller container removing some root mass to balance the drastic pruning... good luck....
Keep in mind, that this should be done in the spring, not in the dead of winter...do not encourage any growth before this time... I hope that other members are willing to give their input too!

Your plants are too leggy and not contained for growth in accordance to our seasonal climate.

 

With all of this great info that you are giving me I feel more confident about "attacking" this mistake I've let go on for one too many years. You've been a great help, K Baron! (One day) when it's a fine-looking Tibouchina I'll post a photo.
thanks again :)