One of my tubifloras bloomed in 2004 and I didn't get a picture! What was I thinking?
The flowers of this species are highly anticipated because of the fragrance, but most people find it difficult to get their plants to bloom. The plant produces plenty of foliage, but no flowers.
On Gesneriphiles, Angelika from Germany posted pictures of her blooming S. tubiflora. At the beginning of July, Gesneriad Society convention-goers saw the United States Botanic Garden's blooming S. tubiflora. At the San Francisco Gesneriad Society meeting in mid-July, Bob Hudak brought in his blooming S. tubiflora. And Lord have mercy, my own plant labored mightily and produced... two flowers and a bud. That's what you see above.
The USBG plant was lush and had many more flowers than mine. Above is a picture.
I believe that more people have difficulty getting S. tubiflora to bloom than any other well-known sinningia species.  The plant is usually easy to grow, and its host of satellite tubers make it easy to propagate. As a result, lots of people have the species and can keep it alive, but few people can get it to bloom.
In the early 1990s, I had a large plant in a wood planter. It bloomed well one year. The next year, the tuber rotted in midsummer. By luck, either bad or good, I had collected seed, so I had some more plants to take up space without producing flowers.
In 2008, I decided to try an experiment. I had three large pots of S. tubiflora, and I placed them in the sunniest locations in the yard. One was right next to a grapevine which fruited heavily, and grapevines are quite demanding about abundant sunlight.
The result was three plants in sunny locations which did not bloom.
In 2009, I put the plants in the same locations, but did it as soon as the tubers began to sprout. For two of the plants, this made no difference. For one, just a bit of difference.
Once again, we repeat a theme for this web site. Successful growers (including everybody, for at least some things) don't know why they succeed unless they also fail. Only by noticing the difference between the conditions of failure and success can we see what's important and what isn't.
Bright light is not enough. Too many plants of Sinningia tubiflora in bright light don't bloom.
One missing element that has been suggested is heat. Higher temperatures, so the argument goes, is required to stimulate flowering in this species, independent of light.
My own tests are not optimistic in this regard. I give my plants as much light and heat as the yard has. As mentioned above, one bloomed, two others didn't.
Another possible factor is water. Here my results are more promising.
A naive grower (such as myself) might be caught assuming that a plant which required lots of light (and perhaps, heat) would be drought-tolerant. For years, I was not diligent about watering them. Recently, I have worked harder at keeping them well-watered. My plants have not been overwhelmed with flowers, by any means, but definitely have borne more of them. So my first guess is that the two most important factors are water and light, with heat not so important.
However, the experiments continue...
|Habit||Upright stem, leaves clustered near the base|
|Dormancy||Stems fully deciduous, multiple tubers (see a picture). Dormancy is obligate.|
|Flower||White, tubular, 7 cm [3 inches] long, scented|
|Hardiness||Has survived 30F (-1C) in my yard.|
|Recommended?||Only if it blooms easily for you. If it does not bloom, this plant is a waste of space. It is very durable, however, so I have half a dozen of them taking up space in my yard.|
|Taxonomic group||The tall-or-sticky group of the Corytholoma clade.|
Ben Paternoster's award-winning plant at the 2004 AGGS convention on Long Island.
As Gloxinia tubiflora by Hooker, in 1842.
As Sinningia tubiflora by Fritsch, in 1894.
Etymology: From Latin tubus ("tube, pipe") + flora ("flower").