Orchids Offer a Range of Flower Longevity
It is interesting to consider how long any flower should or could last if it is not cut from the plant. Certainly the stems, roots and foliage of most plants are much more durable than their flowers. When you think of such temperate plants as the tulip, crabapple or rose, perhaps a week at peak bloom is all you can hope for, or maybe 10 days if the weather is favorable.
Of course, the effective life of any particular blossom or inflorescence varies considerably throughout the plant kingdom. The range may be demonstrated by familiar examples, such as the daylily (Hemerocallis cultivars), with blossoms that last for only a day or so, to the strawflower (Helichrysum species), which produces flowers with vivid bracts that effectively retain their color indefinitely when dried.
It is probably safe to say that most of the orchids popular with hobbyists produce flowers that are at their most beautiful stage for a week or perhaps two. Yet orchid flowers show considerable diversity in floral life as well. While none may be quite so durable as the strawflower, some orchids produce flowers that are effective for weeks or even months, while others, as does the daylily, last just a day.
[NOTE: Sobralia is not in the Cattleya alliance and so this paragraph has been slightly reworded.]
A couple of orchid genera quickly come to mind when one considers flowers of particularly brief duration. One of these is the genus Sobralia, with about 100 species described. The plants are mostly terrestrial and are native to tropical regions in Central and South America. Their canelike stems typically mass into a shrubby habit. Among the species, plant stature varies from 2 or 3 feet (.6 to .9 m) in height to some that tower 9 to 12 feet (2.75 to 3.7 m) tall.
Many Sobralia species produce flowers that are large, showy and colorful. For a few years, I have been trying to cultivate a half dozen species in the landscape of my subtropical garden in South Florida.
Even though it would be a stretch to say that they have thrived, a couple of them produced a number of blossoms this past summer. Sobralia decora has performed the best. My cultivar has a pale violet-pink coloration rather different from others I have seen. I was particularly pleased when my Sobralia leucoxantha flowered. Its large white flowers are accented by bright yellow in the throat of the lip and, indeed, are reminiscent of a white cattleya. Both of these species’ flowers last just a day, but each inflorescence produces a succession of them. Sobralias generally do best in semishaded intermediate conditions. They need to be kept moist in the root zone, which may be my primary difficulty with them, as my soil is sandy. I am considering moving the ones I have back to pots. Friends have told me that they have had good success growing them here in a mix formulated for terrestrial orchids.
Stanhopea is another genus of evanescent orchids. What they lack in floral longevity, however, is more than compensated by their floral intrigue. There are more than 50 species that range from Mexico to Brazil. They are epiphytic and most will thrive in intermediate conditions. Open wire baskets, lined with sphagnum, suit them best, as many inflorescences are produced basally and project downward.
The flowers of stanhopeas must be seen to be believed. They are among the most amazing of all orchids and defy description. Most last but a day or two, and many are fragrant. Nearly any of the species makes a worthy horticultural subject and every orchid grower should try at least one. For me, the bold coloration and large flowers of Stanhopea tigrina are hard to beat. When it comes to floral longevity, few orchids can outperform contemporary phalaenopsis hybrids. I have enjoyed some for more than three months. That is not to imply that each flower lasts that long; however, from the time the first flowers open until the last of an inflorescence fades can easily span most of a season. Indeed, the human eye, which seems to thrive on fresh images, can begin to tire of such long-lasting flowers before they are spent.
The Dendrobium branch of the orchid family also includes some with durable blossoms. Interestingly, some of the longest lasting are the Dendrobium phalaenopsis types from Section Phalaenanthe that today are generally considered varieties of the Dendrobium bigibbum complex. The parent species are found in New Guinea and Australia and their flowers resemble small phalaenopsis blooms. Flower color varies from purple to pink and white. Horticulturally, they require bright light, warm conditions and a dry winter rest. Keep them tightly potted or grow them on slabs. Most of their inflorescences are beautiful for easily a month or more.
Another group of dendrobiums with long-lasting flowers is Section Latouria. from the Philippines to Samoa, the majority of which are found in New Guinea. Many have closely spaced spindle- or club-shaped pseudobulbs with the foliage and flowers produced near their ends. The flowers of some of the larger-flowered species within this group tend to be nodding and they often have petals that are twisted. In recent years, selective breeding has produced considerable improvement in both flower form and carriage. Many of the hybrids are tolerant of a variety of conditions so long as the light is filtered and the plants are kept somewhat moist. Flowers are said to last six to 10 weeks or more on many of them. The hybrid Dendrobium Roy Tokunaga (atroviolaceum × johnsoniae) is a good example. But it is not just genetics that makes a flower long lasting or not. Nutritional and environmental conditions affect floral longevity as well. Excessively hot and dry conditions will usually shorten flower life. Somewhat cooler, humid environments will generally encourage blossoms to last a few days longer. A plant that is nutritionally deprived will often produce short-lived flowers, if it flowers at all. This was brought home to me with my plant of Vanda Pachara Delight (Karulea × Gordon Dillon). I do not grow many vandas because I tend to lack the time and dedication needed to provide the daily watering and regular fertilization that makes them thrive. My V. Pachara Delight was a gift a few years ago and seems to be a game little plant as it regularly produced a spray of five or six dark violet flowers that lasted about 10 days, despite my neglect. Last spring, I resolved to take better care of the plant and upped my commitment to its moisture and nutritional needs. The change was dramatic. The plant began to develop sturdier roots and more of them. Its last flowering produced an inflorescence of nine blossoms that were beautiful for about three weeks.
Perhaps some day, through botanical gene therapy, we can have a stanhopea flower that lasts as long as a phalaenopsis. Until then, look after the environmental and nutritional needs of your orchids as well as you can, so that the flowers they produce will last as long as possible.