I'm in Zone 10 here in west LA, and this past year I've been collecting seeds from the various street trees as I've been delving deeper into the world of dendrology (the study of trees). Finally I decided to pick up some Jiffy pots, greenhouses, and starter soil, and see what would happen. I tried a 2x6 windowsill greenhouse with little peat pucks and put 6 plant and tree types in each pair of pods. I got from them 4 jacarandas (J. mimosifolia), 1 gold medallion (Cassia leptophylla), 4 purple orchid trees (Bauhinia variegata), and eventually 2 explosions of passion vine (Passiflora caerulea). These are all going strong about a month later. Because of the heavily varied germination times and growth-rates, I decided my next greenhouse would be all the same species. Because of the rapid germination and fast growth rate of the orchid trees, they were my choice. I got a 72-puck tabletop greenhouse and planted 2 seeds each in all of them. Exactly half (36) ended up taking, while the rest molded over (any cure for this?) and never grew. The tallest got transplanted - peat pod and all - into 2" Jiffy pots, while the original 2 that I didn't prune from the original 4 have made their way to 5" Jiffy pots. Last weekend I left for 4 days for a family event, so I put everything in a darkened room so they wouldn't suck up all their water in the sunlight. I worried over the trip, but returned to find them 3x their height and quite healthy! It was quite a shock to see so many plants get so huge in 4 days of not taking care of them. Their stems are also far thicker, though they don't have much in the way of leaves - just tiny, starter leaves. Now my questions: 1) Did they grow faster in the dark because they were looking for light, and was this the reason they didn't bother to produce larger leaves? Since returning them to the bright, but indirect light each day, their leaves are all starting to come in fast, but the younger plants have overtaken the original 2 in their larger pots. 2) The stems are much thicker on the new plants than on the 2 originals, though the leaves are still much smaller. Could this be from anything other than the 4 days in the darkened room? Soil, water, light, etc. have been the same otherwise for everything. 3) If I did influence thicker stems and smaller leaves, is this worse, better, or neither for the trees in the long-run? Is there any consensus among gardeners about this? They seem otherwise very healthy, and are currently growing an inch about every 2 days. They're quite eager plants. Now I'm beginning to fear having raised 38 of them in my tiny house :) 4) Do any gardeners use the concept of darkness to influence growth rates? Two things making me feel that plants grow faster and farther in the dark are: a) I have morning glories that grow fairly fast, but nowhere faster than in the dark places they sneak into, like my bedroom through the windowsill area, and through the dark interior of a few plastic storage cabinets they've found their way into through little holes in the back (and in these places they don't form leaves), and b) 2 of my plants have had their seed shells stuck over the leafy parts, and instead of them opening up, the stems have simply grown much taller than the rest of the plants. When I've pulled the shells off to let them grow properly, they've immediately unfurled large leaves and stopped growing taller. Thanks for any info about this growing-in-the-dark mystery.
