Why Are Tibouchina Dying?

Question

Hi: I’ve tried to grow Tibouchina urvilleana in Houston in pots and in the ground for years. Days or months after planting, stems die one at a time without yellowing leaves or evidence of pests or pathogens. Adjacent stems continue to grow and even bloom – for a while. In the ground, other species thrive next to dying Tibouchinas. I’ve tried varying light, water, location, fertilizer and soil (I’m using an azalea mix now, since they like acidic soil), but it seems to make no difference. I’ve been told that the root ball is very sensitive, so I try not to disturb it during planting. Nothing seems to help. The plants from all vendors are gorgeous when I buy them, and it does succeed here – but not for me. I hope that your experts can solve this mystery of slow death. Please answer by e-mail, and you’re welcome to post my dilemma on your site. Thanks for your time and consideration. Dave Sherron

Answer 1

It sounds like the soil remains too moist. This drought tolerant plant will do well with just a little moisture to start out, but they will not tolerate wet soils, at all.

Likely, there is a disease effecting this species left in the soil. If fungicides do not work to kill off the illness, then I could suspect a Mosaic Virus. If this is the case, there is no cure. A virus has no cure, no matter what the living being is, unfortunately. And this one is a permanent installment in your soil, if this is the case.

Your local extension service can check for this, though.

Here are two articles that will help:

https://www.gardeningknowhow.com/ornamental/shrubs/princess-flower-bush/growing-princess-flower.htm

https://www.gardeningknowhow.com/extension-search