Kalanchoë

What’s still green: Conifers, rose stems, yuccas, coral bell, sea pink, Saint John’s wort, yellow evening primrose, Mount Atlas daisy, some grasses

What’s gray or gray-green: Salt bush, winterfat, snow-in-summer, some pinks.

What’s red: Cholla, some pinks, small-leaved soapwort, coral and purple beardtongues, purple aster.

What’s blooming inside: Aptenia, zonal geranium, kalanchoë; Christmas cactus in bud.

Animal sightings: Wherever it is the birds and rabbits are eating, it hasn’t been my yard this past week.

Weather: Snow Monday, very cold Wednesday morning, freeze and thaw ever since; 10:41 hours of daylight today.

Weekly update: Monday, several inches of snow fell on thawed ground. The rest of the week, my boots sank through snow and mud to the freeze line when I trudged in from the drive at night. When I left in the mornings, I negotiated ice-filled, foot-shaped craters. The only consolations for simultaneous thaw and snow was slowly lengthening days and a kalanchoë that’s back in bloom.

A friend brought me the houseplant at work in October 2004. I gave her a smile, gave it a baleful stare, and kept it watered in a florescent-lit office until it went out of bloom. Then, superstitious about living things, I brought the succulent home, and dumped it in with the aptenia on the covered porch. Suddenly, in February it was back in bloom.

The following year it started to bloom in mid-January and continued to produce four-petaled dark-fuschia-colored flowers until September. Last year, the Crassulaceae sent out loose umbrels of color from mid-February to mid-July. This year, it put out its first flowers on January 11.

Kalanchoës are so sensitive to long hours of darkness that growers routinely manipulate the light in their greenhouses to produce flowers for specific market dates. They also follow complex feeding regimens and use growth retardants to keep the flowering stems short. No doubt, perfectly mounded scarlet kalanchoës are being shipped at this very moment for Valentine’s day.

However, it’s not simply the absence of light that matters, but the nature of that light. When I was in grade school, physics was simple: the earth rotated every 24 hours, and orbited the sun every 365 days.

Rainbows represented the full spectrum of visible light and the sun continuously sent the full range of possibilities. However, we only received the full package at noon, which made the skies blue. At dawn and dusk, only the red side of the spectrum could travel the additional distance. The change of seasons was simply a magnification of this pattern: more blue in summer, less in winter.

Understanding physics and light got more complicated after that, but some researchers ignored waves and particles to posit the decline in blue light in winter was what depressed people. Long after I left school, Sterling Hendricks and Harry Borthwick discovered a protein, phytochrome, was the pigment that controlled how plants responded to the far red light between the extreme end of the rainbow and the more famous, invisible infrared light.

No doubt, mathematicians can run calculations that determine the exact amount of darkness required to generate the necessary amount of red light at 6,000' in this part of New Mexico to stimulate kalanchoës to convert from producing dark-green, scallop-edged leaves to reproduction. Botanists have already determined the ratio of far red to in-fared light needed to force a flower to open, close, or remain open despite its circadian rhythms.

On the Tsarantanana massif of northern Madagascar where Perrier de la Bathie found Kalanchoë blossfeldiana growing at 6,666' in 1924, they simply bloom when conditions are right. Mine apparently has reverted, as much as any cutting from a hybrid can revert. Its blooming schedule varies with the kind of November and December we have. Its stems get too long and reach for the light, a sure sign of white to far-red light; the leaves sometimes turn red, signifying too much light; it doesn’t put out as many flowers as it would if it got more blue light. But, it blooms on its own, where in other parts of the country experts tell people to place boxes over their pots to simulate long days or suggest they buy new plants.

So, however much I’ve been complaining about the dreariness of this winter, I have one plant, albeit one indoors, that acts like Pollyanna living in the best of all possible worlds.

Notes:
Engelmann, Wolfgang, Anders Johnsson, H. G. Karlsson, R. Kobler, M.-l. Schimmel. "Attenuation of the Petal Movement Rhythm in Kalanchoë with Light Pulses,"Physiologia Plantarum 43:68-76:1978.

Pérez, M., M.T. Lao, G. Scherer. "Influence of Different Lamps on the Growth and Development on the Short Day Plant Kalanchoe blossfeldiana," Acta Horticulturae 711 (2006).

Photograph: Kalanchoë growing on my east-facing, inside porch, 5 February 2008.