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I planted a Sequoiadendron giganteum (Giant Redwood) sapling today, and I was wondering how many hours of daylight the little guy needs. I found this answer, which mentioned photoperiods of different plants. I haven't been able to find any kind of index of these values by species, and I was wondering if such an index exists. If not, is there some other way I can find out the natural photoperiod of a given species?

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    If you are trying to grow a sequoia indoors much past the seedling stage you need heavy duty High pressure sodium lighting for periods of time that are similar to the daylength of the US West Coast in spring
    – kevinskio
    Feb 28 '15 at 14:47
  • Really? I read that the Sequoiadendron giganteum survive well in mostly shade, unlike the other sequoias- that's how they grow on a forest floor. Right now, I've got it by a window that gets indirect sunlight most of the day. It's only been there for 2 days now, so I don't have any good/bad indicators from it yet. Feb 28 '15 at 23:37
  • I was referring to the dramatic difference in lux levels between indoors at 100 to 500 lux and outside on a sunny day at over 10,000 lux. Low light = etiolation
    – kevinskio
    Feb 28 '15 at 23:46
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Most plants don't care directly about day length for growth. Some have timing requirements to bloom. E.g. Strawberries come in 'june bearing' and 'day neutral' varieties. I don't know if the June ones are triggered by a minimum day length, or a maximum night length. Poinsettias require N days of more than 14 hour long nights to bloom. Spruce use day length to start the process for fall adaptation.

The difference in illumination between full sun and indoors is truly astounding. Your eyes are very good at adjusting to lower levels of illumination. Yes redwoods will grow in the shade of their parents, but they grow VERY slowly. Still, your window has more light than the forest floor of a redwood grove. It should do alright there. Turn it a third of a turn once or twice a week.

I don't know if the day length requirements for redwoods has been determined. In passing however, they do fine in Vancouver B.C. (Don't know if they are coastal or big tree) And Britain's forestry service is considering redwoods as a tree for planting as climate change hits the isles.

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  • Thanks for that. Good to know my redwood will be able to grow OK. That said, do you know of any centralized resource for finding out about the photoperiodism of other plants? (I'm considering creating one if it doesn't already exist.) Mar 1 '15 at 8:22
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    I don't. I was looking for something similar: chilling requirements to break dormancy, and was unable to find such a list. But ask on the UBC botany forum. Mar 2 '15 at 10:09

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