DIY thermograhics

[Andrew Gabriel]

Anyone using full spectrum lighting to grow plants is being horribly wasteful - chlorophyll uses 680nm and 700nm for photosynthesis, so you want a very warm white or even red-ish light (e.g. growlux type lamps).

Some plants need other wavelengths to induce flowers, fruiting, or some other behaviours, but generally not for growing. (I don't know if cannibis needs anything special.)

If you want to light plants decoratively, then you tend to need lots of green, but plants can't use that, which is why they reflect it back at you and therefore look green!

[Owain]

A google suggests:

For the production of chlorophyll, and an optimum photosynthetic reaction, light from the blue spectrum (445 nanometres), and light from the red spectrum (650 nanometres) is necessary.

[Andrew Gabriel]

this works by causing Auxin production which slows growth on the side exposed to the light, so that the plant bends towards the light. In the absence of Auxin, plants grow faster*, so I can't think why Auxin production is regarded as a good thing in the context of growing cannabis (which is what that website seems to be interested in). However, I've never tried.

• Basic O-level biology - grow some cress in the dark, and find that it grows faster than a control sample in the light because there's no Auxin production, until it runs out of energy due to no photosynthesis.

[Owain]

Perhaps if the plants grow too fast there's less of the 'active ingredient' in the same way that modern varieties of vegetables have less vitamins.

Owain

[Andrew Gabriel]

I described doing that a few years back. The DIY scanning arrangement is normally called a wrist.

Also do it from the inside of the house, looking for cold spots on all the external surfaces. The one glaring one I found was the loft hatch, which wasn't insulated (is now).

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember [e-mail] (Andrew Gabriel) saying something like:

There's a helluva lot of bullshit talked about this on various forums. SON-T lighting is all they need; growlux are a ripoff.

[Andrew Gabriel]

SON may work, but 2/3rds of the light output is on the wrong side of the main sodium lines for photosynthesis, and hence wasted.