I can hardly claim to be an expert on any of this, but I can share my anecdotal information, from which folks can draw their own conclusions, if any.
Two years ago, I imported a bunch of bulbs from SA Bulb. All were completely trimmed, with no roots or leaves. Some were summer growers (e.g., Eucomis) and others were various habits, including tender evergreens. I potted everything up and left them alone in the greenhouse with very little watering. I had been advised to just plant the Eucomis in the garden and they might grow or they might just skip it and grow in the following spring. With varying amounts of babying, everything survived and grew well, including the Drimia whose photo I recently posted.
So my first conclusion is that bulbs, unlike orchids, e.g., have so much stored energy that they can hunker down and wait until conditions are right to start growing. I have had some bulbs completely skip a year and then grow the next year as if nothing had happened.
I winter over many tender bulbs, including some aroids, in the back corner of the greenhouse where they are kept cool and dry. In many cases, pots are stacked to conserve floor space. As spring approaches, they come to life, based evidently on temperature as none of them can see any light. Ditto for potted Eucomis that are wintered outside buried in straw and begin sprouting before they are uncovered.
So my second conclusion is that buried bulbs come into growth based on temperature. Actively growing (photosynthesizing) plants can respond to photoperiod to signal blooming or dormancy.
In my efforts to breed more interesting hardy Hippeastrums, I have H. reginae, H. Johnsonii, and some F1 hybrids out of reginae , all of which grow in the ground year round. They tend to bloom in summer. When I dig and divide them in late winter (a week or two ago this year) I pot everything up and put under the greenhouse bench to replant/sell/give away when the weather warms up. All of the pieces sprout rather quickly and the larger ones put up blooms, conveniently coinciding with the more tender ones that normally bloom indoors this time of year. So I have a chance to make some crosses with fresh pollen. Note that the ones in the ground get watered all winter (I just got 6" of rain in two days). So it isn't watering that brings them to life in the greenhouse, nor is it light. All that's left is temperature.
Tim raises the intriguing idea that one might have an imported bulb come to life at the wrong time, and could supplemental lighting be used to ease the plant into the new daylight schedule? This deserves some research, particularly for any plants that perhaps have a reputation for being hard to establish. So far, I got away with letting them figure it out on their own, but I might have had the luxury of dealing with relatively easy-growing species.
As for equatorial plants, in my experience with orchids much of the seasonal behavior coincides with monsoon cycles - cool and totally dry in winter with good sun and some humidity, then watering as temps warm up will trigger the blooms.
Again, just my observations. I don't claim to be a botanist!
Bob E Tenn gloomy and 40 degrees
On Saturday, February 26, 2022, 10:55:37 AM EST, Tim Eck via pbs <pbs@lists.pacificbulbsociety.net> wrote:
The discussion on artificial lighting brought up some questions in my mind
which may have been previously addressed for which I apologize.
1. Would artificial lighting be the way to address the hemispheric
adaptation problem? Assuming the bulbs are received dormant, when they
begin to grow place them under artificial lighting of a period equal to
their natural growth period and keep them at that periodicity until it
matches the outside lIghting period, at which point switch them from
artificial lighting to natural lighting.
2. Is photoperiodicity a thing in equatorial bulbs or are they chiefly
controlled by available moisture?
Thanks
Tim
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