I keep my Solandra, also called cups of gold or Hawaiian lily, at a stunted 1 1/2 feet tall and very tightly potted to fit under the fluorescent grow lights in the basement. So it generally produces only one flower in January. This year, however, it staged its show about a month early and actually had an extra bud waiting in the wings. But that understudy promptly dropped off as soon as I brought the plant up from the basement.
In a container, solandra grows more like a large-leafed shrub than a vine. Strangely enough, the parent of the plant performing now has never bloomed. That parent's larger size may decrease the intensity of light reaching its lower leaves. I should probably cut it back to the same height as its young'un.
The latter proves that Solandra roots very easily, since it was originally just a cutting from its "mother," plopped in a jelly jar with an inch or so of water in the bottom. So I wouldn't bother with rooting hormones for this plant!
Solandra flowers open pale yellow--with maroon veins--and the color deepens in their golden days. There are also silver types, like the grandiflora pictured here, which produce white flowers. The blooms emit a tropical nighttime scent, which has been compared to coconut, banana, or vanilla--or perhaps a combination of the three! Don't let that delicious fragrance deceive you into taking a bite out of your plant, though, as it belongs--like datura and brugmansia--to the poisonous branch of the solanum family.
Be sure to take reasonable precautions while pruning it, since Solandra--like nightshade--contains atropine along with other toxins. Poisonous Plants of Paradise by Susan Scott and Craig Thomas warns that "Rubbing one or both eyes after handling this plant may cause the pupil(s) to dilate. This causes sensitivity to light and blurred vision, which can last for about a week."
And don't make the mistake of actually using the flowers as cups or bowls. That can bring on "nausea, vomiting, headache, and diarrhea." The symptoms, of course, get worse for anybody who actually consumes the plant's flowers or leaves. This is one of those that can kill you, so please treat it with respect. You might want to warn your children against the fruits too. With pointy ends, they look something like tops, and turn from green to pale yellow to red. Fortunately, they aren't very common on cultivated plants.
If you prefer your flowers delicate and symmetrical--and less dangerous, you probably won't appreciate Solandra. Those huge blooms appear a bit lopsided at times and have a stiff, almost leathery feel. The five ruffled lobes that curl back from the cups' rims also lend them a slightly disheveled look. The plant can be a heavyweight bully outdoors too, smothering entire fences and pergolas with vines that run to hundreds of feet.
You should cut those vines back occasionally as more branching reportedly produces more flowers. Although Solandra's strongest bloom period comes during winter or early spring, it can flower intermittently at other times of the year as well when grown outdoors.
Native to Central America and the northern part of South America, it is--according to its PlantFiles entry--hardy in zones 8b to 11. It can tolerate brief periods of freezing weather, but prolonged frost will make it die down to ground level.
So those of you who live in colder climates like mine will have to grow it in a pot if you want to see it bloom. Keep it a bit dry and root bound over the summer, to constrain its size, but water it well during its flowering time. You might want to profit from my mistake, and refrain from moving the plant once it starts blooming too! Conditions upstairs are warmer and less humid than in the basement, which could explain why the extra bud dropped off.
But even one flower of this magnificent plant might be considered an embarrassment of riches, so I'm not complaining. A vine that can bloom this big near the shortest day of the year still seems to me little short of miraculous!
Note: The solandra maxima photo is mine, the solandra grandiflora photo is by TwoWillies of Dave's Garden, and the Solandra grandiflora fruit photo is by Scott Zona, courtesy of Wikimedia Commons.