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Comment by tpmx | Hacker News Reader

So what kind of cannabis do you grow? :-)

cannabis is fine with purple light. My begonias, however, which are supposed to have a bright multicolored foliage as their main feature, come out looking about as impressive as cabbage under purple lights. with a bit of extra "warm white" light they become colorful again.

"peak efficiency" is fine but the rest of what the plant is doing counts too and those less efficient processes may have benefits in the final product.

But does it matter what they look like in the indoor garden under purple lighting? I mean eventually you take them out and admire them in natural lighting. Unless, of course, you have customers visiting your garden...

it matters when i take them out to sell to people as decorative houseplants. they'll adjust to the light they're in in a matter of weeks anyway, but they need to look their best when being shopped to new homes.

You mean the purple color light physically changes the color of the plant? I didn't know that. I tried googling and can't find examples. Can you provide some evidence? It seems hard to believe.

I suspect the OP means, or at least the way I parsed it, is that they'll adjust to the changes to their lighting conditions, not that the light materially affects their physical coloration.

i.e. when someone buys them, they'll have to adjust to natural (i.e. sun) light, rather than the artificial growth lighting.

That isn't hard to believe at all, plants are light abdorbers and the type of light they absorb effects their genetic expression.

If it was true it would be easy to find photographic evidence online. The fact no one in this thread can provide any evidence makes me think this is a rubbish claim.

that's a big assumption, seems like you'd need to find a paper that did an experiment that compared color temps of lights effects on plant leaf color or do some analysis of levels of pigments present in leaves.

Yes, I'd like to see that. I did spend about 15 minutes googling for any evidence similar to this and came up completely empty-handed.

A retail greenhouse would tend to use Metal Halide lighting. It has a wide spectrum that covers human and photosynthetic portions of the spectrum, with a light that looks a lot like natural sunlight. But MH lamps are expensive, hard to install, and can cause fires or explode.

If these LEDs let us design LED fixtures that make both humans plants happy while cutting costs vs MH Lamps, then these lamps will gain market wherever we currently use high quality MH lighting on plants. This might let interior designers substitute MH lamps for plants displays in retail, office, or living spaces.

Likewise, broad spectrum light can reduce fatigue and boost the efficacy of visual plant inspections. If the new LEDs cost the same as the purple LEDs, then indoor farmers may choose the new LEDs to make their work more productive.

I recently became enamored with begonias. The four I’ve collected so far spent the summer outside under my patio and look gorgeous!

One plant was purchased online and arrived with pukey, neutral foliage. After a few months outside, it’s this beautiful, deep, iridescent red on a black border. My wife thinks I’m crazy for how much I fawn over them.

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