Princess Plants (Tibouchina heteromalla and Tibouchina urvilleana.)
Question from Shannon:
I have two sickly Princess Plants (Tibouchina heteromalla) that I planted about 3 months ago. I had had one at the beach (in Playa del Rey CA) that was as big as a house, hearty, and virtually care-free. The ones in question are planted further inland, in Culver City, where the air isn’t as consistently moist. But I have neighbors with healthy, hearty specimens in their yards, while mine are getting more and more bare (yet, strangely, still blooming). A friend said that they are getting too much sun. (They get full sun almost the entire day, from morning to late afternoon.) But when I read about their care, I keep seeing “likes full sun.” I read that they like moist soil, but not too moist. My plants seem to drain well when watered, so I don’t think they’re getting waterlogged. I water every other day or every two days. I’m at a loss. Any suggestions?
Answer from Pat:
See pages 69 and 399 in my book for advice on this plant. Main things all Tibouchinas need are acid soil and constant moisture with good drainage. I thought Tibouchina heteromalla were going to be easier to grow. Most people thought so. Many people purchased them, but they seem short lived. They are definitely not good in containers, they need to be in the ground in rich acid soil with good drainage, constant moisture, and regular organic fertilizer. (Think Hawaii!) Also the cold nights we have had this summer can take its toll on tropicals. I note several I had admired in gardens on my walks while I was writing my book were lovely for a couple or three years. Now all have died—Ooops!—I tried growing Princess tree (Tibouchina urvilleana) in a large tub. No go! I tried it in the ground, in a hole filled with acid soil mix, planting it just like a camellia. (That’s what you have to do.) But my sandy soil and some invasive roots nearby meant curtains for this lovely specimen. I would have needed to leave water running all the time, night and day, for it to survive. We need to face up to the fact that all Tibouchinas are rainforest plants.
Yes, I adore these plants too. You just have to love that vivid purple bloom color and against those soft velvety leaves. Best Tibouchina urvilleana I have ever seen? (I drove by them today as I do almost every day en route to the post office.) They are at least 6 years old, planted next to a lawn, facing north, acid soil, fed constantly, and now in solid bloom, but—oh dear—today they were not looking as good as they used too. Still had a huge number of flowers, but fewer leaves than usual. What is happening? I fear one has died. So there you go! The folks who own that garden have gardeners who are in attendance 2 or 3 days a week and evidently the owners could care less how much money they spend on water or whether we really should be cutting back on watering and going for a more drought-resistant look than what they like, which good old tropical. Across the street from them is a very large and attractively planted drought-resistant garden with excellent design and plant choice. But they own that house also, so I guess they are going for two different looks, wet and tropical on one side of the street, dry on the other.
I have a Princess tree in my back yard that is growing horizontally because no one gave it support when it was smaller and still growing.(We rent but I try to maintain the growing things). Is there anything I can do to rectify the situation? I have tried tying it up but they removed that when they painted the house some months back. It is probably 8-10 tall/long with about 6feet of trunk with no branches(maybe 3 trunks actually)
Are you referring to Princess plant or do you really mean Princess tree? You said Princess tree, so I will take you at your word, but this is the problem with using common names in place of botanical names. It is all too easy to muddle them up. Princess tree (Paulownia tomentosa) is a large semi-tropical tree with large leaves, thick trunk, horizontal branches, and spectacular spring bloom, usually in May when conditions are right. Flower buds form in fall but if the tree is growing in an area of freezing winters, they will be killed and the tree will never bloom. On the other hand, if winter temperatures are too mild with no cold nights dipping into the low 40’s or high 30’s, then all the flower buds will fall off. But when the temperatures are right, the tree is wonderful to behold with fragrant, bell-shaped flowers of lilac blue arising in upright bunches from the tops of branches somewhat like the white blooms of catalpa. Some people don’t like this tree due to its invasive roots and the dense shade it casts but in areas where bloom is reliable it’s easy to be bedazzled by the spring show. If princess tree (Paulownia tomentosa) is the plant you are referring to, be sure to remove two trunks. Leave the strongest one and then get the tree staked upright once more as soon as possible. Also pinch back the tips of the branches to make the foliage fill in. If you are referring to princess plant, which one is it? (There are two: Tibouchina heteromalla and T. urvilleana, which is most frequently seen.) Tibouchina urvilleana is popular but needs acid soil to do well. Both species need sun. If this plant is falling down and growing horizontally, it sounds as if it is reaching for the light. However, Tibouchina heteromalla often grows horizontally, like a cascade. Prop it up with a stake underneath, if necessary. Pinch it back and it should fill out. (By “pinch back” I mean to clip off a few inches from the tip of each branch. This forces growth to fill in back further on the branch. If you could tell me exactly which plant you are growing, this would help me give you a more precise answer, but either one of these will respond to pinching back and staking upright. Fertilize with acid fertilizer about mid-February as soon as the weather warms up and all danger of frost has past.